Has anyone got a function that would move a sprite across an arc please?

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Kevin Cross

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Posted: 27th Oct 2017 21:15 Edited at: 27th Oct 2017 21:20

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Has anyone got a function that would move a sprite across an arc / semi circle/ellipse please like the example I've attached as a video which will hopefully play without me needing to upload it to YouTube? What I've done is ok if it's all I can do but it would be good to get it to move exactly across the edge of the turn template which seems to create an ellipse instead of a proper circle. Here's the code I've used to move the sprite. The biggest problem I see with my example is that I'm going to struggle if the spaceship is at a totally different angle before it starts to turn. So for example if the ship is pointing right (90 degrees) and it turns right it will be turning down towards the bottom of the screen). At the moment I'm just playing around with something.

+ Code Snippet

imgCrapShip = LoadImage("CrapShip.png")
imgRightTurn = LoadImage("RightTurn.png")
sprCrapShip = OryliaCreateSprite("size:-1,10;offset:center;positionByOffset:50,50;image:" + str(imgCrapShip))
sprRightTurn = OryliaCreateSprite("size:-1,30;offset:center;positionByOffset:" + str(GetSpriteXByOffset(sprCrapShip) + (GetSpriteWidth(sprCrapShip) / 2)) + "," + str(GetSpriteYByOffset(sprCrapShip) - (GetSpriteHeight(sprCrapShip) * 0.5)) + ";image:" + str(imgRightTurn))

i = 174
do
	i = i + 2
	if (i > 212) then i = 174
	SetSpritePositionByOffset(sprCrapShip, (27 * cos(i) / GetDisplayAspect()) + 65, 27 * sin(i) + 50)
	SetSpriteAngle(sprCrapShip, i + 180)
    Sync()
loop

Sorry but I put all of my sprite functions into one so that's what the Orylia* functions do.

Maybe I need something that says move the sprite from x,y to x,y and change the angle by X, each step.

http://www.kevincross.co.uk
AGK Code Snippets & Functions

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Kevin Cross

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Posted: 27th Oct 2017 21:24

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Having thought about it I think I've just answered my own question. A funtion that tweens the sprite from x,y to x,y but also tweens the angle.

http://www.kevincross.co.uk
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Kevin Cross

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Posted: 27th Oct 2017 21:24

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Having thought about it I think I've just answered my own question. A funtion that tweens the sprite from x,y to x,y but also tweens the angle.

http://www.kevincross.co.uk
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Kevin Cross

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Posted: 27th Oct 2017 21:26

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I may have trouble working out the x,y position to move to from wherever it's at and the angle etc.

http://www.kevincross.co.uk
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Kevin Cross

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Posted: 28th Oct 2017 08:29

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I was playing around a bit more and got a sprite moving along a path, tweening to different waypoints. Still a little way to go but it got me thinking about creating a utility/tool to create custom paths that can be loaded into a game. So will share that if I get anywhere with it. Couple of math problems I need to work on first.

http://www.kevincross.co.uk
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Markus

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Posted: 28th Oct 2017 09:41

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me thought about using the sprite offset, then you rotate the sprite at circle center.

//#option_explicit

// AGK 2017.09.25 (Tier1 Basic)
// MR 28.10.2017

SetWindowSize(800,600,0,1)
SetVirtualResolution(100,100)

type Pos
	x as float
	y as float
endtype

Main()
end

Function Main()

local spr as integer
	spr= CreateSprite(0)
	SetSpritePositionByOffset(spr,50,50)
	SetSpriteSize(spr,10.0,20.0)
	SetSpriteAngle(spr,-15)
	setspritecolor(spr,128,128,128,255)

local col as integer
	col= MakeColor(255,255,0)
	local mouse as Pos
	local a as float

local x as float
	local y as float

do
		
		print("hold left mouse")

mouse.x= GetPointerX()-50.0
		mouse.y= GetPointerY()-50.0
		
		print(mouse.x)

DrawLine(0,50,100,50,col,col)
				
		if GetPointerstate()=1
			SetSpriteOffset(spr,mouse.x,GetSpriteHeight(spr)/2.0)
		endif
		
		DrawEllipseX(GetWorldXFromSprite(spr,0,0),GetWorldYFromSprite(spr,0,0))
		
		a = GetSpriteAngle(spr)
		a = a + 10.0 / 60.0
		SetSpriteAngle(spr,a)
				
		//if GetPointerPressed() then exit
		
		sync()
	loop
	
EndFunction

Function DrawEllipseX(x as float,y as float)
	
	local col as integer
	col = MakeColor(255,255,0)
	DrawEllipse(x,y,2,2,col,col,1)
	
EndFunction

+ Code Snippet

//#option_explicit

// AGK 2017.09.25 (Tier1 Basic)
// MR 28.10.2017

SetWindowSize(800,600,0,1)
SetVirtualResolution(100,100)

type Pos
	x as float
	y as float
endtype

Main()
end

Function Main()

	local spr as integer
	spr= CreateSprite(0)
	SetSpritePositionByOffset(spr,50,50)
	SetSpriteSize(spr,10.0,20.0)
	SetSpriteAngle(spr,-15)
	setspritecolor(spr,128,128,128,255)

	local col as integer
	col= MakeColor(255,255,0)
	local mouse as Pos
	local a as float

	local x as float
	local y as float

	do
		
		print("hold left mouse")

		mouse.x= GetPointerX()-50.0
		mouse.y= GetPointerY()-50.0
		
		print(mouse.x)

		DrawLine(0,50,100,50,col,col)
				
		if GetPointerstate()=1
			SetSpriteOffset(spr,mouse.x,GetSpriteHeight(spr)/2.0)
		endif
		
		DrawEllipseX(GetWorldXFromSprite(spr,0,0),GetWorldYFromSprite(spr,0,0))
		
		a = GetSpriteAngle(spr)
		a = a + 10.0 / 60.0
		SetSpriteAngle(spr,a)
				
		//if GetPointerPressed() then exit
		
		sync()
	loop
	
EndFunction 

Function DrawEllipseX(x as float,y as float)
	
	local col as integer
	col = MakeColor(255,255,0)
	DrawEllipse(x,y,2,2,col,col,1)
	
EndFunction

AGK (Steam) V2017.09.25 : Windows 10 Pro 64 Bit : AMD (17.9.3) Radeon R7 265 : Mac mini OS High Sierra (10.13)

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Kevin Cross

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Posted: 28th Oct 2017 10:07

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Genius Markus! I didn't think of setting the offset. I do set it in my example by setting it as the centre of the sprite but yes setting it to right of the sprite and a bit further should rotate the sprite around the offset which is a lot easier then sin and cos.

Thank you!

I probably will still look at the path setting tool as that may come in handy at a future date.

http://www.kevincross.co.uk
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Richard_6

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Posted: 28th Oct 2017 15:52

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A path editor? Sounds very interesting! Been trying to make an infite (8) movement.

+ Code Snippet

type point
	x as float
	y as float
	x_dir as float
	y_dir as integer
endtype

mypoint as point[0]
mypoint[0].x = 300
mypoint[0].y = 300
mypoint[0].x_dir=1
mypoint[0].y_dir=1

mysprite as integer
mysprite=create_pet()
main_loop(mypoint, mysprite)

function inf(point ref as point[])
	x as float
	y as float
	scale as float
	scale = 2/(3-cos(2*point[0].x_dir))
	x = (scale*cos(point[0].x_dir))*400
	y = (scale*sin(2*point[0].x_dir)/2)*400
	point[0].x_dir = point[0].x_dir+1
	point[0].x = x
	point[0].y = y
endfunction

function main_loop(point ref as point[], sprite as integer)
	do
		inf(point)
		SetSpritePosition(sprite,point[0].x+100,point[0].y+100)
		sync()
	loop
endfunction
	
function create_pet()
	nome as integer
	nome=createsprite(0)
	setspritesize(nome,100,100)
	SetSpritePosition(nome,100,100)
endfunction nome

The outcome looks ok but then I will have to write one routine for every new shape. Thats why a path editor would be more suitable.

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blink0k

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Posted: 28th Oct 2017 21:42

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Bezier curves

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fubarpk

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Posted: 30th Oct 2017 04:38 Edited at: 30th Oct 2017 05:44

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this may not move your sprite exactly like you want but it will send it from waypoint to waypoint
just add your waypoints click test and away you go a sprite that moves from way point to way point

// Project: Path Editor 
// Created: 2017-10-30

// show all errors
SetErrorMode(2)

#constant clearBtn=1
#constant testBtn=2
#constant exitBtn=3
#constant spr=1
#constant testspr=2
#constant xMax=1024
#constant yMax=768

// set window properties
SetWindowTitle( "Path Editor" )
SetWindowSize( xMax, yMax, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1024, 768 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

CreateSprite (spr,0)
SetSpriteSize (spr,10,10)
CreateSprite (testspr,0)
SetSpriteSize (testspr,10,10)
SetSpriteColor (testspr,0,255,0,255)

AddVirtualButton(clearBtn,40,30,60) //make a button
SetVirtualButtonText( clearBtn, "Clear" ) //set to exit text 
SetVirtualButtonColor( clearBtn,200,200,200)  //grey colour 
AddVirtualButton(testBtn,40,90,60) //make a button
SetVirtualButtonText( testBtn, "Test" ) //set to music text 
SetVirtualButtonColor( testBtn,200,200,200)  //grey colour 
AddVirtualButton(exitBtn,40,150,60) //make a button
SetVirtualButtonText( exitBtn, "Exit" ) //set to sound text 
SetVirtualButtonColor( exitBtn,200,200,200)  //grey colour

renderImg=CreateRenderImage (xMax,yMax,0,0) 
CreateSprite(350,renderImg)

type object
	x as float
	y as float
endtype

count=1
dim path[100] as object
SetSpriteVisible(testspr,0)
SetSpriteDepth(testspr,9)
repeat
    mx#=GetPointerX()
	my#=GetPointerY()
	SetSpritePositionByOffset(spr,mx#,my#) 
	if GetRawMouseLeftPressed() 
		path[count].x=mx#:path[count].y=my#
		SetRenderToImage (renderImg,0) 
		drawSprite(spr)
		inc count
    endif
	if GetVirtualButtonPressed(clearBtn)
		for t = 1 to 100
			path[t].x=0:path[t].y=0
		next t
		DeleteSprite(350):DeleteImage(renderImg)
		renderImg=CreateRenderImage (xMax,yMax,0,0) 
		CreateSprite(350,renderImg) 
		count=1
	endif
		
	Update(0)
	Render()
	setrendertoscreen () 
	
	SetSpriteSize(350,1024,768)

Update(0)
	Render()
	swap()
	
	if GetVirtualButtonPressed(testBtn)
		testPaths()
	endif

until GetVirtualButtonPressed(exitBtn)
end

function testPaths()
x#=path[1].x:y#=path[1].y:count=1:speed#=1
//SetSpriteVisible(350,0)
SetSpriteVisible(testspr,1)

repeat
	SetSpritePositionByOffset(testSpr,x#,y#)	
	//SetSpriteSize(testspr,200,200)
	while getDistance(x#,y#,path[count+1].x,path[count+1].y)>5
		x#=GetSpriteXByOffset(testspr):y#=GetSpriteYByOffset(testspr)
		angle#=getAngle(x#,y#,path[count+1].x,path[count+1].y)
		SetSpritePositionByOffset(testspr,x#-sin(angle#)*speed#,y#+cos(angle#)*speed#)
		SetSpriteAngle(testspr,getAngle(GetSpriteXByOffset(testspr),GetSpriteYByOffset(testspr),xMax/2,yMax/2)):rem point to middle of screen
		//SetSpriteAngle(testspr,angle#):rem point to way point
		print( getDistance(x#,y#,path[count+1].x,path[count+1].y))
		sync()
		
	endwhile	
	//x=path[count+1].x:y=path[count+1].y
	inc count	
	
until path[count+1].x=0 and path[count+1].y=0
SetSpriteVisible(350,1)
SetSpriteVisible(testspr,0)

endfunction

function getAngle(x1#, y1#, x2#, y2#)
    result# = ATanFull(x1# - x2#, y1# - y2#)
endfunction result#

function getDistance (x1#,y1#,x2#,y2#) 
	dx#=x1#-x2#
	dy#=y1#-y2#
	distance#=sqrt((dx#*dx#)+(dy#*dy#)):rem distance object to path point
endfunction distance#

+ Code Snippet

// Project: Path Editor 
// Created: 2017-10-30

// show all errors
SetErrorMode(2)

#constant clearBtn=1
#constant testBtn=2
#constant exitBtn=3
#constant spr=1
#constant testspr=2
#constant xMax=1024
#constant yMax=768

// set window properties
SetWindowTitle( "Path Editor" )
SetWindowSize( xMax, yMax, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1024, 768 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

CreateSprite (spr,0)
SetSpriteSize (spr,10,10)
CreateSprite (testspr,0)
SetSpriteSize (testspr,10,10)
SetSpriteColor (testspr,0,255,0,255)

AddVirtualButton(clearBtn,40,30,60) //make a button
SetVirtualButtonText( clearBtn, "Clear" ) //set to exit text 
SetVirtualButtonColor( clearBtn,200,200,200)  //grey colour 
AddVirtualButton(testBtn,40,90,60) //make a button
SetVirtualButtonText( testBtn, "Test" ) //set to music text 
SetVirtualButtonColor( testBtn,200,200,200)  //grey colour 
AddVirtualButton(exitBtn,40,150,60) //make a button
SetVirtualButtonText( exitBtn, "Exit" ) //set to sound text 
SetVirtualButtonColor( exitBtn,200,200,200)  //grey colour 

renderImg=CreateRenderImage (xMax,yMax,0,0) 
CreateSprite(350,renderImg) 

type object
	x as float
	y as float
endtype

count=1
dim path[100] as object
SetSpriteVisible(testspr,0)
SetSpriteDepth(testspr,9)
repeat
    mx#=GetPointerX()
	my#=GetPointerY()
	SetSpritePositionByOffset(spr,mx#,my#) 
	if GetRawMouseLeftPressed() 
		path[count].x=mx#:path[count].y=my#
		SetRenderToImage (renderImg,0) 
		drawSprite(spr)
		inc count
    endif
	if GetVirtualButtonPressed(clearBtn)
		for t = 1 to 100
			path[t].x=0:path[t].y=0
		next t
		DeleteSprite(350):DeleteImage(renderImg)
		renderImg=CreateRenderImage (xMax,yMax,0,0) 
		CreateSprite(350,renderImg) 
		count=1
	endif
		
	Update(0)
	Render()
	setrendertoscreen () 
	
	SetSpriteSize(350,1024,768)

	Update(0)
	Render()
	swap()
	
	if GetVirtualButtonPressed(testBtn)
		testPaths()
	endif

	
until GetVirtualButtonPressed(exitBtn)
end

function testPaths()
x#=path[1].x:y#=path[1].y:count=1:speed#=1
//SetSpriteVisible(350,0)
SetSpriteVisible(testspr,1)

repeat
	SetSpritePositionByOffset(testSpr,x#,y#)	
	//SetSpriteSize(testspr,200,200)
	while getDistance(x#,y#,path[count+1].x,path[count+1].y)>5
		x#=GetSpriteXByOffset(testspr):y#=GetSpriteYByOffset(testspr)
		angle#=getAngle(x#,y#,path[count+1].x,path[count+1].y)
		SetSpritePositionByOffset(testspr,x#-sin(angle#)*speed#,y#+cos(angle#)*speed#)
		SetSpriteAngle(testspr,getAngle(GetSpriteXByOffset(testspr),GetSpriteYByOffset(testspr),xMax/2,yMax/2)):rem point to middle of screen
		//SetSpriteAngle(testspr,angle#):rem point to way point
		print( getDistance(x#,y#,path[count+1].x,path[count+1].y))
		sync()
		
	endwhile	
	//x=path[count+1].x:y=path[count+1].y
	inc count	
	
until path[count+1].x=0 and path[count+1].y=0
SetSpriteVisible(350,1)
SetSpriteVisible(testspr,0)

endfunction	

function getAngle(x1#, y1#, x2#, y2#)
    result# = ATanFull(x1# - x2#, y1# - y2#)
endfunction result#


function getDistance (x1#,y1#,x2#,y2#) 
	dx#=x1#-x2#
	dy#=y1#-y2#
	distance#=sqrt((dx#*dx#)+(dy#*dy#)):rem distance object to path point
endfunction distance#

simply store the waypoints in an array perhaps a json and then save them
you could also add an another algorithm to the movement that made things move in that formation
by storing the calculated x and y positions and calculating with those and using this to set the current location

fubar

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BatVink

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Posted: 30th Oct 2017 08:12

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Rotating around an offset is OK, but is very limited. Is this for an object that will only follow the same path all of the time?

For example, in a racing game, a car may get shunted off its path. In this scenario, fubarpk's suggestion of waypoints becomes so much more desirable. With waypoints, you can continually readjust the path from where you are now (literally anywhere), to the waypoint.
You can also start to think about sin/cos etc to change the way you turn i.e looking more like a racing driver than a learner driver.

Next...combine with blink0k's suggestion of bezier curves. Now you have a path that you can get any point from, and use these as your waypoints.

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Scraggle

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Posted: 30th Oct 2017 08:45

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FlowFields may also be an option depending on your particular requirements.
They take a little more initial set-up but then they are incredibly easy to use.

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Kevin Cross

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Posted: 30th Oct 2017 17:53

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I continued playing around with it some more and found I got a better result from using sin and cos. So for the problem I was experience I'm going to go with sin and cos like the first bit of code I posted in the first post. That works, although it isn't quite along the line.

I found the offset was causing me problems. Here's an example of the problem: if say the space ship was travelling up in a straight line and you want to turn right you have to use an offset to rotate it but that then re-positions the ship and makes it jump from it's original x position. What I couldn't get to work easily is to move the offset without moving the ship. I did muck about with switching from SetSpritePositionByOffset to SetSpritePosition at certain points but it was all a bit of a faff.

I also looked at joints as that seemed promising but when I rotated the fixed sprite (i.e. the invisible offset point) the ship didn't move. The fixed sprite did spin in it's place though.

This was all for a turn based game so it's not quite as complicated as a fast pace race game and the paths that might be required for that. And physics seem a little pointless in a slow paced turn based game

I still want to look at waypoints (maybe even for this project). I got something set up to place waypoints on the screen with a mouse click and have the sprite follow the path drawn. There's a few bits I need to implement, like being able to move the waypoints once placed, as well as delete and re-order them etc. I also want to draw a line between each point so you can see the path more clearly. I have it so that you can choose the duration of the tween and then that is divided by the number of points, however the problem with this is that if there's not an exact gap between each point some make the sprite move quicker or slower than the other points. What I think I need to do is measure the total distance between all points and then divide the tween duration time by that. In principle that seems like a good solution, and doable.

I've got some more ideas with this but I've pretty much only started it so it's hard to say where I get with it. I do want something that would export a text file that maybe contains an array and a function that can be copied and pasted into any project.

I haven't looked at any of your examples posted above yet as I'm at work and have been away from the forums for a day or two but will have a look through the examples soon to see what I can learn from them.

Thanks

http://www.kevincross.co.uk
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Markus

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Posted: 30th Oct 2017 18:12 Edited at: 30th Oct 2017 18:13

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long ago i used a list of 4 point bezier curves for a track. moving along one bezier curve is just a value between 0 to 1.
i used pre calculated angles to get the car back at track, see screenshots.

blitzmax, Var = ref
p is the return value, TV2D is a Vector Type

+ Code Snippet

Function Bezier4(p:TV2D Var,p1:TV2D,p2:TV2D,p3:TV2D,p4:TV2D,mu:Float)

 'MR 01.07.2005

 'Four control point Bezier interpolation
 'mu ranges from 0 To 1, start To End of curve

 Local mum1:Float,mum13:Float,mu3:Float

 mum1 = 1.0 - mu
 mum13 = mum1 * mum1 * mum1
 mu3 = mu * mu * mu

 p.x = mum13*p1.x + 3.0*mu*mum1*mum1*p2.x + 3.0*mu*mu*mum1*p3.x + mu3*p4.x
 p.y = mum13*p1.y + 3.0*mu*mum1*mum1*p2.y + 3.0*mu*mu*mum1*p3.y + mu3*p4.y
 'p.z = mum13*p1.z + 3.0*mu*mum1*mum1*p2.z + 3.0*mu*mu*mum1*p3.z + mu3*p4.z

End Function

AGK (Steam) V2017.09.25 : Windows 10 Pro 64 Bit : AMD (17.9.3) Radeon R7 265 : Mac mini OS High Sierra (10.13)

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fubarpk

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Posted: 31st Oct 2017 06:28 Edited at: 15th Nov 2017 02:29

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Clonklex's Bevier Curve Library is great a great find blinkok
if you use Bezier Curve Library.agc
found here at the start of Clonkex thread
https://forum.thegamecreators.com/thread/210460

and then with the following changes to my above code
This now allows you to design a path save it and then load
it using an offset means you could for example have a particular alien
movement and then using the offset position anwhere on screen
main.agc

// Project: Path Editor 
// Created: 2017-10-30

// show all errors
SetErrorMode(2)

#constant clearBtn=1
#constant test1Btn=2
#constant test2Btn=3
#constant closedBtn=4
#constant loadBtn=5
#constant saveBtn=6
#constant exitBtn=7
#constant spr=1
#constant xMax=1024
#constant yMax=768
global renderImg=100
global closed=1 //whether or not to draw as open or closed curve

type object
	x as float
	y as float
endtype

type mySpr 
	id as integer
	x as float
	y as float
	xOffset as float
	yOffset as float
endtype

global testSpr as mySpr
testSpr.id=2

#include "include/Bezier Curve Library.agc"

gosub _bc_setup //this has to be called before any BC command, preferably before anything at all

// set window properties
SetWindowTitle( "Path Editor" )
SetWindowSize( xMax, yMax, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1024, 768 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

CreateSprite (spr,0)
SetSpriteSize (spr,10,10)
CreateSprite (testSpr.id,0)
SetSpriteSize (testSpr.id,10,10)
SetSpriteColor (testSpr.id,0,255,0,255)
SetSpritePositionByOffset(testSpr.id,xMax/2,yMax/2)

AddVirtualButton(clearBtn,40,30,60) //make a button
SetVirtualButtonText( clearBtn, "Clear" ) //set to exit text 
SetVirtualButtonColor( clearBtn,200,200,200)  //grey colour 
AddVirtualButton(test1Btn,40,90,60) //make a button
SetVirtualButtonText( test1Btn, "Test Points" ) //set to music text 
SetVirtualButtonColor( test1Btn,200,200,200)  //grey colour 
AddVirtualButton(test2Btn,40,150,60) //make a button
SetVirtualButtonText( test2Btn, "Test Bezier" ) //set to music text 
SetVirtualButtonColor( test2Btn,200,200,200)  //grey colour 
AddVirtualButton(closedBtn,40,210,60) //make a button
if closed=1 
	SetVirtualButtonText( closedBtn, "Closed" ) //set to music text 
else
	SetVirtualButtonText( closedBtn, "Open" ) //set to music text
endif
SetVirtualButtonColor( closedBtn,200,200,200)  //grey colour 
AddVirtualButton(saveBtn,40,270,60) //make a button
SetVirtualButtonText( saveBtn, "Save" ) //set to music text 
SetVirtualButtonColor( saveBtn,200,200,200)  //grey colour 
AddVirtualButton(loadBtn,40,330,60) //make a button
SetVirtualButtonText( loadBtn, "Load" ) //set to music text 
SetVirtualButtonColor( loadBtn,200,200,200)  //grey colour 
AddVirtualButton(exitBtn,40,390,60) //make a button
SetVirtualButtonText( exitBtn, "Exit" ) //set to sound text 
SetVirtualButtonColor( exitBtn,200,200,200)  //grey colour

CreateRenderImage (renderImg,xMax,yMax,0,0) 
CreateSprite(350,renderImg)

count=1
dim path[100] as object
SetSpriteVisible(testSpr.id,0)
SetSpriteDepth(testSpr.id,9)
repeat
    mx#=GetPointerX()
	my#=GetPointerY()
	SetSpritePositionByOffset(spr,mx#,my#) 
	if GetRawMouseLeftPressed() 
		path[count].x=mx#:path[count].y=my#
		SetRenderToImage (renderImg,0) 
		drawSprite(spr)
		bc_addcurvepoint(getrawmousex(),getrawmousey())
		if closed=0
			bc_calculateopencurvesegmentpoints()
		else
			bc_calculateclosedcurvesegmentpoints()
		endif
		inc count
    endif
	if GetVirtualButtonPressed(clearBtn)
		clearPoints()
		count=1
	endif
		
	Update(0)
	Render()
	setrendertoscreen () 
	
	SetSpriteSize(350,1024,768)

Update(0)
	Render()
	swap()
	
	if GetVirtualButtonPressed(closedBtn)
		if closed=1 
			closed=0
			SetVirtualButtonText( closedBtn, "Open" ) // 
		else
			closed=1
			SetVirtualButtonText( closedBtn, "Closed" ) //
		endif
	endif
	
	if GetVirtualButtonPressed(test1Btn)
		testPaths()
	endif

if GetVirtualButtonPressed(test2Btn)
		drawBezier()
		testBezierCurve()
		//Bezier2()
	endif
	
	if GetVirtualButtonPressed(saveBtn)
		saveArray(count)
	endif
	if GetVirtualButtonPressed(loadBtn)
		count=loadArray()
	endif

until GetVirtualButtonPressed(exitBtn)
end

function clearPoints ()
for t = 0 to 100
	path[t].x=0:path[t].y=0
next t
BC_RemoveCurvePoints()
DeleteSprite(350):DeleteImage(renderImg)
renderImg=CreateRenderImage (xMax,yMax,0,0) 
CreateSprite(350,renderImg) 
endfunction

function drawBezier()
if bc_getcurvesegmentpointcount()>0
	SetRenderToImage (renderImg,0) 
	for i=0 to bc_getcurvesegmentpointcount()-2 //normally use -1, but I want to stop 1 early of the end of the array
		drawline(bc_getcurvesegmentpointx(i),bc_getcurvesegmentpointy(i),bc_getcurvesegmentpointx(i+1),bc_getcurvesegmentpointy(i+1),255,0,0)
 	next i
endif
Update(0)
Render()
setrendertoscreen () 
Update(0)
Render()
swap()
	
endfunction

function testBezierCurve()
testSpr.xOffset=0:testSpr.yOffset=0
SetSpriteVisible(testSpr.id,1)
if bc_getcurvesegmentpointcount()>0
	for i=0 to bc_getcurvesegmentpointcount()-1 //normally use -1, but I want to stop 1 early of the end of the array
		SetSpritePositionByOffset(testSpr.id,bc_getcurvesegmentpointx(i)+testSpr.xOffset,bc_getcurvesegmentpointy(i)+testSpr.yOffset)
		//add following to point to centre
		angle#=getAngle(bc_getcurvesegmentpointx(i),bc_getcurvesegmentpointy(i),bc_getcurvesegmentpointx(i+1),bc_getcurvesegmentpointy(i+1))
		SetSpriteAngle(testSpr.id,getAngle(GetSpriteXByOffset(testSpr.id),GetSpriteYByOffset(testSpr.id),xMax/2,yMax/2)):rem point to middle of screen
		sync()
 	next i
endif
SetSpriteVisible(350,1)
SetSpriteVisible(testSpr.id,0)
endfunction

function testPaths()
//testSpr.x=xMax/2:testSpr.y=yMax/2
testSpr.xOffset=0:testSpr.yOffset=0

testSpr.x=path[1].x+testSpr.xOffset:testSpr.y=path[1].y+testSpr.yOffset
count=1:speed#=5
//SetSpriteVisible(350,0)
SetSpriteVisible(testSpr.id,1)

repeat
	SetSpritePositionByOffset(testSpr.id,testSpr.x,testSpr.y)	
	//SetSpriteSize(testspr,200,200)
	while getDistance(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y)>5
		angle#=getAngle(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y)
		testSpr.x=testSpr.x-sin(angle#)*speed#:testSpr.y=testSpr.y+cos(angle#)*speed#
		SetSpritePositionByOffset(testSpr.id,testSpr.x+testSpr.xOffset,testSpr.y+testSpr.yOffset)
		SetSpriteAngle(testSpr.id,getAngle(GetSpriteXByOffset(testSpr.id),GetSpriteYByOffset(testSpr.id),xMax/2,yMax/2)):rem point to middle of screen
		//SetSpriteAngle(testspr,angle#):rem point to way point
		print( getDistance(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y))
		sync()
		
	endwhile	
	//x=path[count+1].x:y=path[count+1].y
	inc count	
	
until path[count+1].x=0 and path[count+1].y=0
SetSpriteVisible(350,1)
SetSpriteVisible(testSpr.id,0)

endfunction

function getAngle(x1#, y1#, x2#, y2#)
    result# = ATanFull(x1# - x2#, y1# - y2#)
endfunction result#

function getDistance (x1#,y1#,x2#,y2#) 
	dx#=x1#-x2#
	dy#=y1#-y2#
	distance#=sqrt((dx#*dx#)+(dy#*dy#)):rem distance object to path point
endfunction distance#

function difference(x as float ,y as float)
diff as float
diff = (x-y)
endfunction diff

//Function Bezier4(p:TV2D Var,p1:TV2D,p2:TV2D,p3:TV2D,p4:TV2D,mu:Float)
function Bezier2()
//MR 01.07.2005

//Four control point Bezier interpolation
//mu ranges from 0 To 1, start To End of curve
mu as float
mum1 as float
mum13 as float
mu3 as float
count as integer

SetSpriteVisible(testSpr.id,1)
for mu=0 to 1 step .025
	mum1 = 1.0 - mu
	mum13 = mum1 * mum1 * mum1
	mu3 = mu * mu * mu
	testSpr.x = mum13*path[1].x + (3.0*mu*mum1*mum1*path[2].x) + (3.0*mu*mu*mum1*path[3].x) + (mu3*path[4].x)
	testSpr.y = mum13*path[1].y + (3.0*mu*mum1*mum1*path[2].y) + (3.0*mu*mu*mum1*path[3].y) + (mu3*path[4].y)
	//p.z = mum13*p1.z + 3.0*mu*mum1*mum1*p2.z + 3.0*mu*mu*mum1*p3.z + mu3*p4.z
	SetSpritePositionByOffset(testSpr.id,testSpr.x,testSpr.y)
	Print(testSpr.x)
	sync()
next mu
//SetSpriteVisible(testSpr.id,0)
EndFunction

function saveArray(count as integer)
write = OpenToWrite("array.txt" ,0)
length=count 
String$ = Str(length)
WriteLine (write,String$)
WriteLine (write,Str(closed))
for num=0 to length
	StringX$ = Str(path[num].x)
	StringY$ = Str(path[num].y)
	WriteLine (write,StringX$)
	WriteLine (write,StringY$)
next num
Closefile(write)
endfunction

function loadArray()
for t = 0 to 100
	path[t].x=0:path[t].y=0
next t

If GetFileExists("array.txt")
	read = OpenToRead("array.txt")
	String1$ = ReadLine(read)
	length=val(String1$):length=3
	String2$ = ReadLine(read)
	closed=val(String2$)
	BC_RemoveCurvePoints()
	//dim path[length] as object
	for num =1 to length
		StringX$ = ReadLine(read)
		StringY$ = ReadLine(read)
		path[num].x=val(StringX$)
		path[num].y=val(StringY$)	
		
		SetRenderToImage (renderImg,0) 
		SetSpritePosition(spr,path[num].x,path[num].y)
		drawSprite(spr)
		bc_addcurvepoint(path[num].x,path[num].y)
		if closed=0
			bc_calculateopencurvesegmentpoints()
		else
			bc_calculateclosedcurvesegmentpoints()
		endif
		Update(0)
		Render()
		setrendertoscreen () 
	
		SetSpriteSize(350,1024,768)

Update(0)
		Render()
		swap()
	next num
	Closefile(read)
	if closed=1 
		SetVirtualButtonText( closedBtn, "Closed" ) //set to music text 
	else
		SetVirtualButtonText( closedBtn, "Open" ) //set to music text
	endif
	count=length
	
endif
endfunction count

+ Code Snippet


// Project: Path Editor 
// Created: 2017-10-30

// show all errors
SetErrorMode(2)

#constant clearBtn=1
#constant test1Btn=2
#constant test2Btn=3
#constant closedBtn=4
#constant loadBtn=5
#constant saveBtn=6
#constant exitBtn=7
#constant spr=1
#constant xMax=1024
#constant yMax=768
global renderImg=100
global closed=1 //whether or not to draw as open or closed curve

type object
	x as float
	y as float
endtype

type mySpr 
	id as integer
	x as float
	y as float
	xOffset as float
	yOffset as float
endtype

global testSpr as mySpr
testSpr.id=2

#include "include/Bezier Curve Library.agc"

gosub _bc_setup //this has to be called before any BC command, preferably before anything at all

// set window properties
SetWindowTitle( "Path Editor" )
SetWindowSize( xMax, yMax, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1024, 768 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

CreateSprite (spr,0)
SetSpriteSize (spr,10,10)
CreateSprite (testSpr.id,0)
SetSpriteSize (testSpr.id,10,10)
SetSpriteColor (testSpr.id,0,255,0,255)
SetSpritePositionByOffset(testSpr.id,xMax/2,yMax/2)

AddVirtualButton(clearBtn,40,30,60) //make a button
SetVirtualButtonText( clearBtn, "Clear" ) //set to exit text 
SetVirtualButtonColor( clearBtn,200,200,200)  //grey colour 
AddVirtualButton(test1Btn,40,90,60) //make a button
SetVirtualButtonText( test1Btn, "Test Points" ) //set to music text 
SetVirtualButtonColor( test1Btn,200,200,200)  //grey colour 
AddVirtualButton(test2Btn,40,150,60) //make a button
SetVirtualButtonText( test2Btn, "Test Bezier" ) //set to music text 
SetVirtualButtonColor( test2Btn,200,200,200)  //grey colour 
AddVirtualButton(closedBtn,40,210,60) //make a button
if closed=1 
	SetVirtualButtonText( closedBtn, "Closed" ) //set to music text 
else
	SetVirtualButtonText( closedBtn, "Open" ) //set to music text
endif
SetVirtualButtonColor( closedBtn,200,200,200)  //grey colour 
AddVirtualButton(saveBtn,40,270,60) //make a button
SetVirtualButtonText( saveBtn, "Save" ) //set to music text 
SetVirtualButtonColor( saveBtn,200,200,200)  //grey colour 
AddVirtualButton(loadBtn,40,330,60) //make a button
SetVirtualButtonText( loadBtn, "Load" ) //set to music text 
SetVirtualButtonColor( loadBtn,200,200,200)  //grey colour 
AddVirtualButton(exitBtn,40,390,60) //make a button
SetVirtualButtonText( exitBtn, "Exit" ) //set to sound text 
SetVirtualButtonColor( exitBtn,200,200,200)  //grey colour 

CreateRenderImage (renderImg,xMax,yMax,0,0) 
CreateSprite(350,renderImg) 

count=1
dim path[100] as object
SetSpriteVisible(testSpr.id,0)
SetSpriteDepth(testSpr.id,9)
repeat
    mx#=GetPointerX()
	my#=GetPointerY()
	SetSpritePositionByOffset(spr,mx#,my#) 
	if GetRawMouseLeftPressed() 
		path[count].x=mx#:path[count].y=my#
		SetRenderToImage (renderImg,0) 
		drawSprite(spr)
		bc_addcurvepoint(getrawmousex(),getrawmousey())
		if closed=0
			bc_calculateopencurvesegmentpoints()
		else
			bc_calculateclosedcurvesegmentpoints()
		endif
		inc count
    endif
	if GetVirtualButtonPressed(clearBtn)
		clearPoints()
		count=1
	endif
		
	Update(0)
	Render()
	setrendertoscreen () 
	
	SetSpriteSize(350,1024,768)

	Update(0)
	Render()
	swap()
	
	if GetVirtualButtonPressed(closedBtn)
		if closed=1 
			closed=0
			SetVirtualButtonText( closedBtn, "Open" ) // 
		else
			closed=1
			SetVirtualButtonText( closedBtn, "Closed" ) //
		endif
	endif
	
	if GetVirtualButtonPressed(test1Btn)
		testPaths()
	endif

	if GetVirtualButtonPressed(test2Btn)
		drawBezier()
		testBezierCurve()
		//Bezier2()
	endif
	
	if GetVirtualButtonPressed(saveBtn)
		saveArray(count)
	endif
	if GetVirtualButtonPressed(loadBtn)
		count=loadArray()
	endif	
	

	
until GetVirtualButtonPressed(exitBtn)
end

function clearPoints ()
for t = 0 to 100
	path[t].x=0:path[t].y=0
next t
BC_RemoveCurvePoints()
DeleteSprite(350):DeleteImage(renderImg)
renderImg=CreateRenderImage (xMax,yMax,0,0) 
CreateSprite(350,renderImg) 
endfunction

function drawBezier()
if bc_getcurvesegmentpointcount()>0
	SetRenderToImage (renderImg,0) 
	for i=0 to bc_getcurvesegmentpointcount()-2 //normally use -1, but I want to stop 1 early of the end of the array
		drawline(bc_getcurvesegmentpointx(i),bc_getcurvesegmentpointy(i),bc_getcurvesegmentpointx(i+1),bc_getcurvesegmentpointy(i+1),255,0,0)
 	next i
endif
Update(0)
Render()
setrendertoscreen () 
Update(0)
Render()
swap()
	
endfunction

function testBezierCurve()
testSpr.xOffset=0:testSpr.yOffset=0
SetSpriteVisible(testSpr.id,1)
if bc_getcurvesegmentpointcount()>0
	for i=0 to bc_getcurvesegmentpointcount()-1 //normally use -1, but I want to stop 1 early of the end of the array
		SetSpritePositionByOffset(testSpr.id,bc_getcurvesegmentpointx(i)+testSpr.xOffset,bc_getcurvesegmentpointy(i)+testSpr.yOffset)
		//add following to point to centre
		angle#=getAngle(bc_getcurvesegmentpointx(i),bc_getcurvesegmentpointy(i),bc_getcurvesegmentpointx(i+1),bc_getcurvesegmentpointy(i+1))
		SetSpriteAngle(testSpr.id,getAngle(GetSpriteXByOffset(testSpr.id),GetSpriteYByOffset(testSpr.id),xMax/2,yMax/2)):rem point to middle of screen
		sync()
 	next i
endif
SetSpriteVisible(350,1)
SetSpriteVisible(testSpr.id,0)
endfunction

function testPaths()
//testSpr.x=xMax/2:testSpr.y=yMax/2
testSpr.xOffset=0:testSpr.yOffset=0

testSpr.x=path[1].x+testSpr.xOffset:testSpr.y=path[1].y+testSpr.yOffset
count=1:speed#=5
//SetSpriteVisible(350,0)
SetSpriteVisible(testSpr.id,1)

repeat
	SetSpritePositionByOffset(testSpr.id,testSpr.x,testSpr.y)	
	//SetSpriteSize(testspr,200,200)
	while getDistance(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y)>5
		angle#=getAngle(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y)
		testSpr.x=testSpr.x-sin(angle#)*speed#:testSpr.y=testSpr.y+cos(angle#)*speed#
		SetSpritePositionByOffset(testSpr.id,testSpr.x+testSpr.xOffset,testSpr.y+testSpr.yOffset)
		SetSpriteAngle(testSpr.id,getAngle(GetSpriteXByOffset(testSpr.id),GetSpriteYByOffset(testSpr.id),xMax/2,yMax/2)):rem point to middle of screen
		//SetSpriteAngle(testspr,angle#):rem point to way point
		print( getDistance(testSpr.x,testSpr.y,path[count+1].x,path[count+1].y))
		sync()
		
	endwhile	
	//x=path[count+1].x:y=path[count+1].y
	inc count	
	
until path[count+1].x=0 and path[count+1].y=0
SetSpriteVisible(350,1)
SetSpriteVisible(testSpr.id,0)

endfunction	

function getAngle(x1#, y1#, x2#, y2#)
    result# = ATanFull(x1# - x2#, y1# - y2#)
endfunction result#


function getDistance (x1#,y1#,x2#,y2#) 
	dx#=x1#-x2#
	dy#=y1#-y2#
	distance#=sqrt((dx#*dx#)+(dy#*dy#)):rem distance object to path point
endfunction distance#

function difference(x as float ,y as float)
diff as float
diff = (x-y)
endfunction diff

//Function Bezier4(p:TV2D Var,p1:TV2D,p2:TV2D,p3:TV2D,p4:TV2D,mu:Float)
function Bezier2()
//MR 01.07.2005

//Four control point Bezier interpolation
//mu ranges from 0 To 1, start To End of curve
mu as float
mum1 as float
mum13 as float
mu3 as float
count as integer

SetSpriteVisible(testSpr.id,1)
for mu=0 to 1 step .025
	mum1 = 1.0 - mu
	mum13 = mum1 * mum1 * mum1
	mu3 = mu * mu * mu
	testSpr.x = mum13*path[1].x + (3.0*mu*mum1*mum1*path[2].x) + (3.0*mu*mu*mum1*path[3].x) + (mu3*path[4].x)
	testSpr.y = mum13*path[1].y + (3.0*mu*mum1*mum1*path[2].y) + (3.0*mu*mu*mum1*path[3].y) + (mu3*path[4].y)
	//p.z = mum13*p1.z + 3.0*mu*mum1*mum1*p2.z + 3.0*mu*mu*mum1*p3.z + mu3*p4.z
	SetSpritePositionByOffset(testSpr.id,testSpr.x,testSpr.y)
	Print(testSpr.x)
	sync()
next mu
//SetSpriteVisible(testSpr.id,0)
EndFunction

function saveArray(count as integer)
write = OpenToWrite("array.txt" ,0)
length=count 
String$ = Str(length)
WriteLine (write,String$)
WriteLine (write,Str(closed))
for num=0 to length
	StringX$ = Str(path[num].x)
	StringY$ = Str(path[num].y)
	WriteLine (write,StringX$)
	WriteLine (write,StringY$)
next num
Closefile(write)
endfunction

function loadArray()
for t = 0 to 100
	path[t].x=0:path[t].y=0
next t

If GetFileExists("array.txt")
	read = OpenToRead("array.txt")
	String1$ = ReadLine(read)
	length=val(String1$):length=3
	String2$ = ReadLine(read)
	closed=val(String2$)
	BC_RemoveCurvePoints()
	//dim path[length] as object
	for num =1 to length
		StringX$ = ReadLine(read)
		StringY$ = ReadLine(read)
		path[num].x=val(StringX$)
		path[num].y=val(StringY$)	
		
		SetRenderToImage (renderImg,0) 
		SetSpritePosition(spr,path[num].x,path[num].y)
		drawSprite(spr)
		bc_addcurvepoint(path[num].x,path[num].y)
		if closed=0
			bc_calculateopencurvesegmentpoints()
		else
			bc_calculateclosedcurvesegmentpoints()
		endif
		Update(0)
		Render()
		setrendertoscreen () 
	
		SetSpriteSize(350,1024,768)

		Update(0)
		Render()
		swap()
	next num
	Closefile(read)
	if closed=1 
		SetVirtualButtonText( closedBtn, "Closed" ) //set to music text 
	else
		SetVirtualButtonText( closedBtn, "Open" ) //set to music text
	endif
	count=length
	
endif
endfunction count

Clonklex's Bevier Curve Library

/*
---------------------------------------------------------
----         Bezier Curve Library v1.21 (BASIC)      ----
----            By Clonkex aka David Hynd            ----
----           Created 12/03/14 - 11/04/14           ----
---------------------------------------------------------

Legal:

Do what you want with it. Have fun! xD

Changes:

[20/03/14] 1.0  - Public release
[21/03/14] 1.1  - Fixed closed curves (so they actually work and all that)
[22/03/14] 1.11 - Tiny eency little fix (forgot to change an X to a Y)
[22/03/14] 1.2  - Fixed some floats not being floats and wrote the C++ version of the library
[11/04/14] 1.21 - Fixed some bugs in the C++ version related to for-loops

Usage:

Coming soon (i.e. when I feel like writing it). For now look at the example.

Function list:

BC_AddCurvePoint(posx#,posy#)                  -- Adds a new point to the curve at the specified position
BC_RemoveCurvePoints()                         -- Removes all points from the curve
BC_CalculatePointOnOpenCurve(t#)               -- Finds a point on the curve from distance along it in a range of 0-1; calculates an open-ended curve
BC_CalculatePointOnClosedCurve(t#)             -- Finds a point on the curve from distance along it in a range of 0-1; calculates a closed curve
BC_GetCurvePointCount()                        -- Returns the number of points currently making up the curve
BC_GetCurvePointX()                            -- Returns the last calculated position from BC_CalculatePointOnXXXCurve()
BC_GetCurvePointY()                            -- Returns the last calculated position from BC_CalculatePointOnXXXCurve()
BC_CalculateClosestPointToCurve(x#,y#)         -- Finds the closest point on the curve to the position; call BC_CalculateXXXCurveSegmentPoints() first!
BC_GetClosestPointX()                          -- Returns the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointY()                          -- Returns the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointDistance()                   -- Returns the distance to the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointIndex()                      -- Returns the index of the last calculated segment point from BC_CalculateClosestPointToCurve()
BC_SetCurveSegmentPointCount(count)            -- Sets how many segment points should be created from the curve
BC_GetCurveSegmentPointCount()                 -- Returns the number generated of segment points
BC_GetCurveSegmentPointX(index)                -- Returns the position of a specific segment point
BC_GetCurveSegmentPointY(index)                -- Returns the position of a specific segment point
BC_CalculateOpenCurveSegmentPoints()           -- Cuts up a curve into a set number of points (segment points) making straight lines
BC_CalculateClosedCurveSegmentPoints()         -- Cuts up a curve into a set number of points (segment points) making straight lines
BC_Distance(x1#,y1#,x2#,y2#)                   -- Used internally; calculates the distance between two 2D points
BC_PointOnLineX(x1#,y1#,x2#,y2#,percent#)      -- Used internally; calculates a position based on a distance along a 2D line
BC_PointOnLineY(x1#,y1#,x2#,y2#,percent#)      -- Used internally; calculates a position based on a distance along a 2D line

*/

_BC_Setup:
global bc_lastcurvepointx#=0.0
global bc_lastcurvepointy#=0.0
global bc_curvepointcount=0
global bc_distanceiterations=50
global bc_closestdistance#=0.0
global bc_closestpointx#=0.0
global bc_closestpointy#=0.0
global bc_closestindex=0
global bc_curvesegmentpointcount=0
type bc_curvepointinfo
 posx# as float
 posy# as float
endtype
type bc_curvesegmentpointinfo
 posx# as float
 posy# as float
endtype
dim bc_curvepoint[0] as bc_curvepointinfo
dim bc_curvesegmentpoint[0] as bc_curvesegmentpointinfo
return

function BC_AddCurvePoint(posx#,posy#)
 bc_curvepointcount=bc_curvepointcount+1
 dim bc_curvepoint[bc_curvepointcount] as bc_curvepointinfo
 bc_curvepoint[bc_curvepointcount-1].posx#=posx#
 bc_curvepoint[bc_curvepointcount-1].posy#=posy#
endfunction

function BC_RemoveCurvePoints()
 bc_curvepointcount=0
 dim bc_curvepoint[bc_curvepointcount] as bc_curvepointinfo
 bc_curvesegmentpointcount=0
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
endfunction

function BC_CalculatePointOnOpenCurve(t#) //t# is the percentage of the way along the line in a range of 0-1
 if bc_curvepointcount>1
  totalt#=t#*(bc_curvepointcount-1)
  i=trunc(totalt#)
  realt#=totalt#-i
  p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
  p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
  p2posx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  p2posy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  if i=0
   p0posx#=bc_curvepoint[i].posx#
   p0posy#=bc_curvepoint[i].posy#
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  endif
  if i=bc_curvepointcount-2
   p3posx#=bc_curvepoint[i+1].posx#
   p3posy#=bc_curvepoint[i+1].posy#
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
   p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
   p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
  endif
  //begin calculations (conveniently adapted from http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/):
  u#=1-realt#
  tt#=realt#*realt#
  uu#=u#*u#
  uuu#=uu#*u#
  ttt#=tt#*realt#
  bc_lastcurvepointx#=uuu#*p0posx# //first term
  bc_lastcurvepointy#=uuu#*p0posy# //first term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*uu#*realt#*p1posx# //second term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*uu#*realt#*p1posy# //second term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*u#*tt#*p2posx# //third term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*u#*tt#*p2posy# //third term
  bc_lastcurvepointx#=bc_lastcurvepointx#+ttt#*p3posx# //fourth term
  bc_lastcurvepointy#=bc_lastcurvepointy#+ttt#*p3posy# //fourth term
 else
  if bc_curvepointcount>0
   bc_lastcurvepointx#=bc_curvepoint[0].posx#
   bc_lastcurvepointy#=bc_curvepoint[0].posy#
  else
   message("Bezier Curve Library: Tried to calculate a curve with no points! You douchebag!")
   end
  endif
 endif
endfunction

function BC_CalculatePointOnClosedCurve(t#) //t# is the percentage of the way along the line in a range of 0-1
 if bc_curvepointcount>1
  totalt#=t#*bc_curvepointcount
  i=trunc(totalt#)
  realt#=totalt#-i
  if i=bc_curvepointcount-1
   p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p2posx#=bc_pointonlinex(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
   p2posy#=bc_pointonliney(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  else
   p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
   p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
   p2posx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
   p2posy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  endif
  if i=0
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[bc_curvepointcount-1].posx#,bc_curvepoint[bc_curvepointcount-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[bc_curvepointcount-1].posx#,bc_curvepoint[bc_curvepointcount-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  endif
  if i=bc_curvepointcount-2
   tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
   p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
  else
   if i=bc_curvepointcount-1
    tempx#=bc_pointonlinex(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[1].posx#,bc_curvepoint[1].posy#,0.3333)
    tempy#=bc_pointonliney(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[1].posx#,bc_curvepoint[1].posy#,0.3333)
    p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
    p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
   else
    tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
    tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
    p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
    p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
   endif
  endif
  //begin calculations (conveniently adapted from http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/):
  u#=1-realt#
  tt#=realt#*realt#
  uu#=u#*u#
  uuu#=uu#*u#
  ttt#=tt#*realt#
  bc_lastcurvepointx#=uuu#*p0posx# //first term
  bc_lastcurvepointy#=uuu#*p0posy# //first term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*uu#*realt#*p1posx# //second term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*uu#*realt#*p1posy# //second term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*u#*tt#*p2posx# //third term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*u#*tt#*p2posy# //third term
  bc_lastcurvepointx#=bc_lastcurvepointx#+ttt#*p3posx# //fourth term
  bc_lastcurvepointy#=bc_lastcurvepointy#+ttt#*p3posy# //fourth term
 else
  if bc_curvepointcount>0
   bc_lastcurvepointx#=bc_curvepoint[0].posx#
   bc_lastcurvepointy#=bc_curvepoint[0].posy#
  else
   message("Bezier Curve Library: Tried to calculate a curve with no points! You douchebag!")
   end
  endif
 endif
endfunction

function BC_GetCurvePointCount()
endfunction bc_curvepointcount

function BC_GetCurvePointX()
endfunction bc_lastcurvepointx#

function BC_GetCurvePointY()
endfunction bc_lastcurvepointy#

function BC_CalculateClosestPointToCurve(posx#,posy#) //x# and y# are the point from which we're searching
 bc_closestdistance#=1000000 //hack, but basically could never be larger than this anyway
 if bc_curvepointcount>0
  bc_closestpointx#=0
  bc_closestpointy#=0
  for i=0 to bc_distanceiterations-1
   distance#=bc_distance(posx#,posy#,bc_curvesegmentpoint[i].posx#,bc_curvesegmentpoint[i].posy#)
   if distance#<bc_closestdistance#
    bc_closestdistance#=distance#
    bc_closestpointx#=bc_curvesegmentpoint[i].posx#
    bc_closestpointy#=bc_curvesegmentpoint[i].posy#
    bc_closestindex=i
   endif
  next i
 else
  bc_closestpointx#=0
  bc_closestpointy#=0
 endif
endfunction

function BC_GetClosestPointX()
endfunction bc_closestpointx#

function BC_GetClosestPointY()
endfunction bc_closestpointy#

function BC_GetClosestPointDistance()
endfunction bc_closestdistance#

function BC_GetClosestPointIndex()
endfunction bc_closestindex

function BC_SetCurveSegmentPointCount(count)
 bc_distanceiterations=count
endfunction

function BC_GetCurveSegmentPointCount()
endfunction bc_curvesegmentpointcount

function BC_GetCurveSegmentPointX(index)
 x#=bc_curvesegmentpoint[index].posx#
endfunction x#

function BC_GetCurveSegmentPointY(index)
 y#=bc_curvesegmentpoint[index].posy#
endfunction y#

function BC_CalculateOpenCurveSegmentPoints()
 bc_curvesegmentpointcount=bc_distanceiterations
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
 if bc_curvepointcount>0
  add#=1.0/bc_distanceiterations
  t#=0
  for i=0 to bc_curvesegmentpointcount-1
   bc_calculatepointonopencurve(t#)
   bc_curvesegmentpoint[i].posx#=bc_lastcurvepointx#
   bc_curvesegmentpoint[i].posy#=bc_lastcurvepointy#
   t#=t#+add#
  next i
 endif
endfunction

function BC_CalculateClosedCurveSegmentPoints()
 bc_curvesegmentpointcount=bc_distanceiterations
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
 if bc_curvepointcount>0
  add#=1.0/bc_distanceiterations
  t#=0
  for i=0 to bc_curvesegmentpointcount-1
   if i=bc_distanceiterations-1 then t#=0.9999999
   bc_calculatepointonclosedcurve(t#)
   bc_curvesegmentpoint[i].posx#=bc_lastcurvepointx#
   bc_curvesegmentpoint[i].posy#=bc_lastcurvepointy#
   t#=t#+add#
  next i
 endif
endfunction

function BC_Distance(x1#,y1#,x2#,y2#)
 dx#=x1#-x2#
 dy#=y1#-y2#
 distance#=sqrt(dx#*dx#+dy#*dy#)
endfunction distance#

function BC_PointOnLineX(x1#,y1#,x2#,y2#,percent#)
 px#=x1#+((x2#-x1#)*percent#)
endfunction px#

function BC_PointOnLineY(x1#,y1#,x2#,y2#,percent#)
 py#=y1#+((y2#-y1#)*percent#)
endfunction py#

+ Code Snippet

/*
---------------------------------------------------------
----         Bezier Curve Library v1.21 (BASIC)      ----
----            By Clonkex aka David Hynd            ----
----           Created 12/03/14 - 11/04/14           ----
---------------------------------------------------------

Legal:

Do what you want with it. Have fun! xD


Changes:

[20/03/14] 1.0  - Public release
[21/03/14] 1.1  - Fixed closed curves (so they actually work and all that)
[22/03/14] 1.11 - Tiny eency little fix (forgot to change an X to a Y)
[22/03/14] 1.2  - Fixed some floats not being floats and wrote the C++ version of the library
[11/04/14] 1.21 - Fixed some bugs in the C++ version related to for-loops


Usage:

Coming soon (i.e. when I feel like writing it). For now look at the example.


Function list:

BC_AddCurvePoint(posx#,posy#)                  -- Adds a new point to the curve at the specified position
BC_RemoveCurvePoints()                         -- Removes all points from the curve
BC_CalculatePointOnOpenCurve(t#)               -- Finds a point on the curve from distance along it in a range of 0-1; calculates an open-ended curve
BC_CalculatePointOnClosedCurve(t#)             -- Finds a point on the curve from distance along it in a range of 0-1; calculates a closed curve
BC_GetCurvePointCount()                        -- Returns the number of points currently making up the curve
BC_GetCurvePointX()                            -- Returns the last calculated position from BC_CalculatePointOnXXXCurve()
BC_GetCurvePointY()                            -- Returns the last calculated position from BC_CalculatePointOnXXXCurve()
BC_CalculateClosestPointToCurve(x#,y#)         -- Finds the closest point on the curve to the position; call BC_CalculateXXXCurveSegmentPoints() first!
BC_GetClosestPointX()                          -- Returns the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointY()                          -- Returns the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointDistance()                   -- Returns the distance to the last calculated closest position from BC_CalculateClosestPointToCurve()
BC_GetClosestPointIndex()                      -- Returns the index of the last calculated segment point from BC_CalculateClosestPointToCurve()
BC_SetCurveSegmentPointCount(count)            -- Sets how many segment points should be created from the curve
BC_GetCurveSegmentPointCount()                 -- Returns the number generated of segment points
BC_GetCurveSegmentPointX(index)                -- Returns the position of a specific segment point
BC_GetCurveSegmentPointY(index)                -- Returns the position of a specific segment point
BC_CalculateOpenCurveSegmentPoints()           -- Cuts up a curve into a set number of points (segment points) making straight lines
BC_CalculateClosedCurveSegmentPoints()         -- Cuts up a curve into a set number of points (segment points) making straight lines
BC_Distance(x1#,y1#,x2#,y2#)                   -- Used internally; calculates the distance between two 2D points
BC_PointOnLineX(x1#,y1#,x2#,y2#,percent#)      -- Used internally; calculates a position based on a distance along a 2D line
BC_PointOnLineY(x1#,y1#,x2#,y2#,percent#)      -- Used internally; calculates a position based on a distance along a 2D line

*/


_BC_Setup:
global bc_lastcurvepointx#=0.0
global bc_lastcurvepointy#=0.0
global bc_curvepointcount=0
global bc_distanceiterations=50
global bc_closestdistance#=0.0
global bc_closestpointx#=0.0
global bc_closestpointy#=0.0
global bc_closestindex=0
global bc_curvesegmentpointcount=0
type bc_curvepointinfo
 posx# as float
 posy# as float
endtype
type bc_curvesegmentpointinfo
 posx# as float
 posy# as float
endtype
dim bc_curvepoint[0] as bc_curvepointinfo
dim bc_curvesegmentpoint[0] as bc_curvesegmentpointinfo
return

function BC_AddCurvePoint(posx#,posy#)
 bc_curvepointcount=bc_curvepointcount+1
 dim bc_curvepoint[bc_curvepointcount] as bc_curvepointinfo
 bc_curvepoint[bc_curvepointcount-1].posx#=posx#
 bc_curvepoint[bc_curvepointcount-1].posy#=posy#
endfunction

function BC_RemoveCurvePoints()
 bc_curvepointcount=0
 dim bc_curvepoint[bc_curvepointcount] as bc_curvepointinfo
 bc_curvesegmentpointcount=0
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
endfunction

function BC_CalculatePointOnOpenCurve(t#) //t# is the percentage of the way along the line in a range of 0-1
 if bc_curvepointcount>1
  totalt#=t#*(bc_curvepointcount-1)
  i=trunc(totalt#)
  realt#=totalt#-i
  p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
  p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
  p2posx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  p2posy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  if i=0
   p0posx#=bc_curvepoint[i].posx#
   p0posy#=bc_curvepoint[i].posy#
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  endif
  if i=bc_curvepointcount-2
   p3posx#=bc_curvepoint[i+1].posx#
   p3posy#=bc_curvepoint[i+1].posy#
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
   p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
   p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
  endif
  //begin calculations (conveniently adapted from http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/):
  u#=1-realt#
  tt#=realt#*realt#
  uu#=u#*u#
  uuu#=uu#*u#
  ttt#=tt#*realt#
  bc_lastcurvepointx#=uuu#*p0posx# //first term
  bc_lastcurvepointy#=uuu#*p0posy# //first term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*uu#*realt#*p1posx# //second term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*uu#*realt#*p1posy# //second term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*u#*tt#*p2posx# //third term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*u#*tt#*p2posy# //third term
  bc_lastcurvepointx#=bc_lastcurvepointx#+ttt#*p3posx# //fourth term
  bc_lastcurvepointy#=bc_lastcurvepointy#+ttt#*p3posy# //fourth term
 else
  if bc_curvepointcount>0
   bc_lastcurvepointx#=bc_curvepoint[0].posx#
   bc_lastcurvepointy#=bc_curvepoint[0].posy#
  else
   message("Bezier Curve Library: Tried to calculate a curve with no points! You douchebag!")
   end
  endif
 endif
endfunction

function BC_CalculatePointOnClosedCurve(t#) //t# is the percentage of the way along the line in a range of 0-1
 if bc_curvepointcount>1
  totalt#=t#*bc_curvepointcount
  i=trunc(totalt#)
  realt#=totalt#-i
  if i=bc_curvepointcount-1
   p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p2posx#=bc_pointonlinex(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
   p2posy#=bc_pointonliney(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  else
   p1posx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
   p1posy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,0.3333)
   p2posx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
   p2posy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,0.3333)
  endif
  if i=0
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[bc_curvepointcount-1].posx#,bc_curvepoint[bc_curvepointcount-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[bc_curvepointcount-1].posx#,bc_curvepoint[bc_curvepointcount-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  else
   tempx#=bc_pointonlinex(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i].posx#,bc_curvepoint[i].posy#,bc_curvepoint[i-1].posx#,bc_curvepoint[i-1].posy#,0.3333)
   p0posx#=bc_pointonlinex(tempx#,tempy#,p1posx#,p1posy#,0.5)
   p0posy#=bc_pointonliney(tempx#,tempy#,p1posx#,p1posy#,0.5)
  endif
  if i=bc_curvepointcount-2
   tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,0.3333)
   p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
   p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
  else
   if i=bc_curvepointcount-1
    tempx#=bc_pointonlinex(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[1].posx#,bc_curvepoint[1].posy#,0.3333)
    tempy#=bc_pointonliney(bc_curvepoint[0].posx#,bc_curvepoint[0].posy#,bc_curvepoint[1].posx#,bc_curvepoint[1].posy#,0.3333)
    p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
    p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
   else
    tempx#=bc_pointonlinex(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
    tempy#=bc_pointonliney(bc_curvepoint[i+1].posx#,bc_curvepoint[i+1].posy#,bc_curvepoint[i+2].posx#,bc_curvepoint[i+2].posy#,0.3333)
    p3posx#=bc_pointonlinex(p2posx#,p2posy#,tempx#,tempy#,0.5)
    p3posy#=bc_pointonliney(p2posx#,p2posy#,tempx#,tempy#,0.5)
   endif
  endif
  //begin calculations (conveniently adapted from http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/):
  u#=1-realt#
  tt#=realt#*realt#
  uu#=u#*u#
  uuu#=uu#*u#
  ttt#=tt#*realt#
  bc_lastcurvepointx#=uuu#*p0posx# //first term
  bc_lastcurvepointy#=uuu#*p0posy# //first term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*uu#*realt#*p1posx# //second term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*uu#*realt#*p1posy# //second term
  bc_lastcurvepointx#=bc_lastcurvepointx#+3*u#*tt#*p2posx# //third term
  bc_lastcurvepointy#=bc_lastcurvepointy#+3*u#*tt#*p2posy# //third term
  bc_lastcurvepointx#=bc_lastcurvepointx#+ttt#*p3posx# //fourth term
  bc_lastcurvepointy#=bc_lastcurvepointy#+ttt#*p3posy# //fourth term
 else
  if bc_curvepointcount>0
   bc_lastcurvepointx#=bc_curvepoint[0].posx#
   bc_lastcurvepointy#=bc_curvepoint[0].posy#
  else
   message("Bezier Curve Library: Tried to calculate a curve with no points! You douchebag!")
   end
  endif
 endif
endfunction

function BC_GetCurvePointCount()
endfunction bc_curvepointcount

function BC_GetCurvePointX()
endfunction bc_lastcurvepointx#

function BC_GetCurvePointY()
endfunction bc_lastcurvepointy#

function BC_CalculateClosestPointToCurve(posx#,posy#) //x# and y# are the point from which we're searching
 bc_closestdistance#=1000000 //hack, but basically could never be larger than this anyway
 if bc_curvepointcount>0
  bc_closestpointx#=0
  bc_closestpointy#=0
  for i=0 to bc_distanceiterations-1
   distance#=bc_distance(posx#,posy#,bc_curvesegmentpoint[i].posx#,bc_curvesegmentpoint[i].posy#)
   if distance#<bc_closestdistance#
    bc_closestdistance#=distance#
    bc_closestpointx#=bc_curvesegmentpoint[i].posx#
    bc_closestpointy#=bc_curvesegmentpoint[i].posy#
    bc_closestindex=i
   endif
  next i
 else
  bc_closestpointx#=0
  bc_closestpointy#=0
 endif
endfunction

function BC_GetClosestPointX()
endfunction bc_closestpointx#

function BC_GetClosestPointY()
endfunction bc_closestpointy#

function BC_GetClosestPointDistance()
endfunction bc_closestdistance#

function BC_GetClosestPointIndex()
endfunction bc_closestindex

function BC_SetCurveSegmentPointCount(count)
 bc_distanceiterations=count
endfunction

function BC_GetCurveSegmentPointCount()
endfunction bc_curvesegmentpointcount

function BC_GetCurveSegmentPointX(index)
 x#=bc_curvesegmentpoint[index].posx#
endfunction x#

function BC_GetCurveSegmentPointY(index)
 y#=bc_curvesegmentpoint[index].posy#
endfunction y#

function BC_CalculateOpenCurveSegmentPoints()
 bc_curvesegmentpointcount=bc_distanceiterations
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
 if bc_curvepointcount>0
  add#=1.0/bc_distanceiterations
  t#=0
  for i=0 to bc_curvesegmentpointcount-1
   bc_calculatepointonopencurve(t#)
   bc_curvesegmentpoint[i].posx#=bc_lastcurvepointx#
   bc_curvesegmentpoint[i].posy#=bc_lastcurvepointy#
   t#=t#+add#
  next i
 endif
endfunction

function BC_CalculateClosedCurveSegmentPoints()
 bc_curvesegmentpointcount=bc_distanceiterations
 dim bc_curvesegmentpoint[bc_curvesegmentpointcount] as bc_curvesegmentpointinfo
 if bc_curvepointcount>0
  add#=1.0/bc_distanceiterations
  t#=0
  for i=0 to bc_curvesegmentpointcount-1
   if i=bc_distanceiterations-1 then t#=0.9999999
   bc_calculatepointonclosedcurve(t#)
   bc_curvesegmentpoint[i].posx#=bc_lastcurvepointx#
   bc_curvesegmentpoint[i].posy#=bc_lastcurvepointy#
   t#=t#+add#
  next i
 endif
endfunction

function BC_Distance(x1#,y1#,x2#,y2#)
 dx#=x1#-x2#
 dy#=y1#-y2#
 distance#=sqrt(dx#*dx#+dy#*dy#)
endfunction distance#

function BC_PointOnLineX(x1#,y1#,x2#,y2#,percent#)
 px#=x1#+((x2#-x1#)*percent#)
endfunction px#

function BC_PointOnLineY(x1#,y1#,x2#,y2#,percent#)
 py#=y1#+((y2#-y1#)*percent#)
endfunction py#

Plotting three points and selecting the Bezier curve option mimmicks your video
If you want to try the waypoints option ive added an offset testSpr.xOffset and testSpr.yOffset
they can be calculated by getting the difference from where you want the sprite and the location
they was first plotted and putting it in the offset variables arcs work with closed=0
If you wish to change closed to open or visa versa remember to clear after
Work to do make it so as you can have many different paths saved and load each one for
individual alien movements

fubar

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tmu

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Joined: 2nd Feb 2017

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Posted: 11th Nov 2017 14:37

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Going with Markus's pics, I would ry to just plot some points long the path. Keep track which points the object has passed through. Target the next point in the list that has not been passed through. Set sprite angle always to face the point it is moving towards. Add minor randomness to make it look more sexy. That's just a hypothetical though ofcourse, never done it for this type of game. Used it to target stuff similarly and have enemies move towards player but not for some list of points. All these bezier curves and whatnot just sound complicated.

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AppGameKit Classic Chat / Has anyone got a function that would move a sprite across an arc please?

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