Want to take a look at some math?

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basicFanatic

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Posted: 28th Apr 2020 14:58

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So, I have these values:

aVal# = 310
bVal# = 320

x = 100
xMax = 200

x and xMax work like a percentage system, with xMax representing 100%.
but in the case above I set xMax to 200 and set x to 100, so here, x works like 50 %

I want to calculate a value that is between aVal# and bVal#, and use x to slide between them.
In the example above x is practically 50 %, so the result would be smack in the middle, that is 315
If x was 0 we would get 310
if x was 200 we would get 320

What should I do to get those results?

If you're curious, I'm trying to place a string of brush dabs, the number depending on how far the cursor have moved.

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Scraggle

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Location: Yorkshire

Posted: 28th Apr 2020 15:13 Edited at: 28th Apr 2020 15:13

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Here's a snippet from my personal maths library:

+ Code Snippet

//**********************************
// Map 
//**********************************
//Scales  a value within the 'in range' to one that fits in the 'out range'
//Useful for a slider for example: The 'in range' is the length of the graphical slider and the 'out range' is the value you want to output (0-100) or (0-256) maybe
function Map(value as float, inMin as float, inMax as float, outMin as float, outMax as float)
	// Figure out how 'wide' each range is
	leftSpan# = inMax - inMin
	rightSpan# = outMax - outMin

	// Convert the left range into a 0-1 range (float)
	valueScaled# = (value - inMin) / leftSpan#

	// Convert the 0-1 range into a value in the right range.
	ret# = outMin + (valueScaled# * rightSpan#)
endfunction ret#

I think that's what you're looking for.

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Qugurun

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Playing: AppGameKit

Posted: 28th Apr 2020 16:34

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SetClearColor(0,100,255)

global startVal# = 300
global endVal# = 700
global widthVal# = 0

global Xprogress = 200
global Yprogress = 300

global xMin = 0
global xMax = 100
global xPos = 73 // <--change %

//====================================================
global progress_back
progress_back = CreateSprite(0)
SetSpriteColor(progress_back, 50, 60, 90, 255)
SetSpriteSize(progress_back, endVal#-startVal#, 30)
SetSpritePosition(progress_back, Xprogress, Yprogress )

//----------------------------------------------------
global progress_front
progress_front = CreateSprite(0)
SetSpriteColor(progress_front, 240, 70, 60, 255)
SetSpriteSize(progress_front, endVal#-startVal#, 30)
SetSpritePosition(progress_front, Xprogress, Yprogress )
//====================================================
SetPercentValue(xPos) //Set %
do
	print("progress_front X: "+str(GetSpriteX(progress_front)))
	print("progress_front Y: "+str(GetSpriteY(progress_front)))
	print("progress_front Width: "+str(GetSpriteWidth(progress_front)))
	print("progress_front Height: "+str(GetSpriteHeight(progress_front)))
	print("percent: "+str(xPos))
	
	
    Sync()
loop

function SetPercentValue ( i as integer )
	widthVal#=(endVal#-startVal#)/xMax*i
	SetSpriteSize(progress_front, widthVal#, GetSpriteHeight(progress_front))
endfunction

+ Code Snippet

SetClearColor(0,100,255)

global startVal# = 300
global endVal# = 700
global widthVal# = 0

global Xprogress = 200
global Yprogress = 300

global xMin = 0
global xMax = 100
global xPos = 73 // <--change %


//====================================================
global progress_back
progress_back = CreateSprite(0)
SetSpriteColor(progress_back, 50, 60, 90, 255)
SetSpriteSize(progress_back, endVal#-startVal#, 30)
SetSpritePosition(progress_back, Xprogress, Yprogress )

//----------------------------------------------------
global progress_front
progress_front = CreateSprite(0)
SetSpriteColor(progress_front, 240, 70, 60, 255)
SetSpriteSize(progress_front, endVal#-startVal#, 30)
SetSpritePosition(progress_front, Xprogress, Yprogress )
//====================================================
SetPercentValue(xPos) //Set %
do
	print("progress_front X: "+str(GetSpriteX(progress_front)))
	print("progress_front Y: "+str(GetSpriteY(progress_front)))
	print("progress_front Width: "+str(GetSpriteWidth(progress_front)))
	print("progress_front Height: "+str(GetSpriteHeight(progress_front)))
	print("percent: "+str(xPos))
	
	
    Sync()
loop

function SetPercentValue ( i as integer )
	widthVal#=(endVal#-startVal#)/xMax*i
	SetSpriteSize(progress_front, widthVal#, GetSpriteHeight(progress_front))
endfunction

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hendron

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Joined: 20th Dec 2015

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Posted: 28th Apr 2020 16:55 Edited at: 28th Apr 2020 16:56

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Scraggle's function should work if your control range (x) needs to start at any value other than 0. If not, you can just use this formula:

result# = aVal# + (bVal# - aVal#) * (x# / xMax#)

x and xMax need to be declared as floats for it to work.

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Phaelax

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Location: Metropia

Posted: 28th Apr 2020 18:11

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What you want is called linear interpolation.

value = aVal# + (bVal#-aVal#) * t

Where 't' is your percentage value, a decimal between 0 and 1. If you need to calculate that percentage value: (these should all be floats)

max_range = bVal#-aVal#

percent = current_value / max_range

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basicFanatic

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Joined: 7th Jun 2017

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Posted: 28th Apr 2020 20:05

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Thanks all!

Getting the brush strokes to scale correctly over time was That Big Task, the one I really didn't think I could pull off. Partly because I needed to pull apart a lot of the code to fit it in. But this morning I woke early and wrote some pseudocode which sounded about right. Then I tried it and ... nope, didn't work at all, the brush daps were all over the place. I found out what line gave the trouble, asked around here, copypasted Scraggles' code and ...yet again it didn't work. Then I found out I had switched around some parameters, and stuff just worked! Honestly, it felt magical.

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