firing turret angle help - GameCreators Forum

Author

Message

sovr

14

Years of Service

User Offline

Joined: 2nd Jan 2010

Location: USA

Posted: 30th Nov 2011 15:46

Link

hello, I am developing an agk app that has a turret in the middle of the map and you are firing at enemies. The thing I am having trouble with is when I rotate the turret how can I make the bullet shoot out in the direction of the turret? I guess I could do a ton of if statement that checks for the angle of the turret, but anyone else have a better way? thank you!

sov the game creator!

Back to top

Profile PM Email Website

bitJericho

21

Years of Service

User Offline

Joined: 9th Oct 2002

Location: United States

Posted: 30th Nov 2011 15:57

Link

Quote: " I guess I could do a ton of if statement that checks for the angle of the turret, but anyone else have a better way? thank you!"

Look up the angle of the turrent and then align the new object in the same direction, and then thrust it forward.

Check out the following commands:
GetSpriteAngle
SetSpriteAngle

Back to top

Profile PM Email Website

DennisW

15

Years of Service

User Offline

Joined: 15th Jun 2008

Location: Ohio

Posted: 30th Nov 2011 16:23

Link

Hi
I am working on the same type of thing. I have the x and y and the angle what is the line of code that would be to thrust it forward on a stright line.

Dennis

Ham and Eggs Breakfast
The Chicken was involved the Pig was Committed

Back to top

Profile PM Email Website

Cliff Mellangard 3DEGS

Developer

18

Years of Service

User Offline

Joined: 20th Feb 2006

Location: Sweden

Posted: 30th Nov 2011 16:55 Edited at: 30th Nov 2011 16:58

Link

i use these functions in my boinkadroid game for my turrets.
The point to command can you simply adjust with -90 or something if it points wrongly.

+ Code Snippet

function Point_TO(id,x#,y#,x2#,y2#)
    sprite_new_angle# = atanfull(x2#-x#,y2#-y#)
    SetSpriteAngle(id,sprite_new_angle#)
endfunction


function Move_To( id , originalX# , originalY# , destinationX# , destinationY# , move# )

    ontarget=0
    distanceX# = destinationX# - originalX#
    distanceY# = destinationY# - originalY#
    distanceFromAtoB# = sqrt ( ( distanceX# * distanceX# ) + ( distanceY# * distanceY# ) )

    if ( distanceFromAtoB# <> 0.0 )
       directionX# = distanceX# / distanceFromAtoB#
       directionY# = distanceY# / distanceFromAtoB#
    endif
    if ( move# > distanceFromAtoB# ) or (distanceFromAtoB#<move#)
        ontarget=1
        //ExitFunction ontarget
    endif
    if ontarget=0
       // work out new location
       newX# = originalX# + directionX# * move#
       newY# = originalY# + directionY# * move#

       // update position of our sprite
       SetSpritePosition ( id , newX#, newY# )
    endif

endfunction ontarget

Back to top

Profile PM Website

bitJericho

21

Years of Service

User Offline

Joined: 9th Oct 2002

Location: United States

Posted: 30th Nov 2011 17:42

Link

This command would apply a force.

SetSpritePhysicsForce

To calculate the correct x and y force, you need to use sin and cos on the angle of your sprite.

Xforce = speed * Cos(angle)
Yforce = speed * Sin(angle)

Back to top

Profile PM Email Website

3d point in space

14

Years of Service

User Offline

Joined: 30th Jun 2009

Location: Idaho

Posted: 30th Nov 2011 18:27 Edited at: 30th Nov 2011 18:30

Link

Well you need to know several things about the turret because it rotates.

First you need to fire from the center point.

This is actually taken out of my game.

void Resetendata(int xxw,int xxp,bool torf)
{

float xdistfromcenter;
    float ydistfromcenter;
    float len;
    float lendirx;
    float lendiry;
	
	playanden[xxw].g_Bullets[g_bulletplace2].rateoffire=3.0;

if(!playanden[xxw].g_Bullets[g_bulletplace2].bActive&&playanden[xxw].life>=3.0)
    {
	
		//float rotangle2=agk::ATanFull(agk::GetSpriteX(playanden[xxw].id)-agk::GetSpriteX(player.playerid),agk::GetSpriteY(playanden[xxw].id)-agk::GetSpriteY(player.playerid));
		if(torf)
		{
		playanden[xxw].life=0;
		}
		if(playanden[xxw].xxc<19)
		{
			xdistfromcenter=24;
			ydistfromcenter=18;
		}
	
		else
		{
			xdistfromcenter=49;
			ydistfromcenter=48;
		}
		
		
        len=sqrt((xdistfromcenter)*(xdistfromcenter)+(ydistfromcenter)*(ydistfromcenter));
		
        lendirx=agk::Sin(rotangle2+180+xxp)*len;
        lendiry=agk::Cos(rotangle2+180+xxp)*len; 
		
	
		playanden[xxw].g_Bullets[g_bulletplace2].accx=-agk::Sin(rotangle2)*playanden[xxw].g_Bullets[g_bulletplace2].rateoffire;
		playanden[xxw].g_Bullets[g_bulletplace2].accy=agk::Cos(rotangle2)*playanden[xxw].g_Bullets[g_bulletplace2].rateoffire;

if(playanden[xxw].xxc==15)
		{
			playanden[xxw].g_Bullets[g_bulletplace2].xcord=lendirx+agk::GetSpriteX(playanden[xxw].id)+xdistfromcenter;
            
       playanden[xxw].g_Bullets[g_bulletplace2].ycord=-lendiry+agk::GetSpriteY(playanden[xxw].id)+ydistfromcenter+45;
		}
		else
		{
		playanden[xxw].g_Bullets[g_bulletplace2].xcord=lendirx+agk::GetSpriteX(playanden[xxw].id)+xdistfromcenter;
            
       playanden[xxw].g_Bullets[g_bulletplace2].ycord=-lendiry+agk::GetSpriteY(playanden[xxw].id)+ydistfromcenter;
		}
        playanden[xxw].g_Bullets[g_bulletplace2].angle=rotangle2;
		playanden[xxw].g_Bullets[g_bulletplace2].fLife=0.0f;
        playanden[xxw].g_Bullets[g_bulletplace2].bActive=true;
		g_bulletplace2++;
	
            //	agk::Print(g_bulletplace);
         if(g_bulletplace2==79)
         {
            g_bulletplace2=0;
         }
	}
	
}

+ Code Snippet

void Resetendata(int xxw,int xxp,bool torf)
{

    float xdistfromcenter;
    float ydistfromcenter;
    float len;
    float lendirx;
    float lendiry;
	
	playanden[xxw].g_Bullets[g_bulletplace2].rateoffire=3.0;

	if(!playanden[xxw].g_Bullets[g_bulletplace2].bActive&&playanden[xxw].life>=3.0)
    {
	
		//float rotangle2=agk::ATanFull(agk::GetSpriteX(playanden[xxw].id)-agk::GetSpriteX(player.playerid),agk::GetSpriteY(playanden[xxw].id)-agk::GetSpriteY(player.playerid));
		if(torf)
		{
		playanden[xxw].life=0;
		}
		if(playanden[xxw].xxc<19)
		{
			xdistfromcenter=24;
			ydistfromcenter=18;
		}
	
		else
		{
			xdistfromcenter=49;
			ydistfromcenter=48;
		}
		
		
        len=sqrt((xdistfromcenter)*(xdistfromcenter)+(ydistfromcenter)*(ydistfromcenter));
		
        lendirx=agk::Sin(rotangle2+180+xxp)*len;
        lendiry=agk::Cos(rotangle2+180+xxp)*len; 
		
	
		playanden[xxw].g_Bullets[g_bulletplace2].accx=-agk::Sin(rotangle2)*playanden[xxw].g_Bullets[g_bulletplace2].rateoffire;
		playanden[xxw].g_Bullets[g_bulletplace2].accy=agk::Cos(rotangle2)*playanden[xxw].g_Bullets[g_bulletplace2].rateoffire;

		if(playanden[xxw].xxc==15)
		{
			playanden[xxw].g_Bullets[g_bulletplace2].xcord=lendirx+agk::GetSpriteX(playanden[xxw].id)+xdistfromcenter;
            
       playanden[xxw].g_Bullets[g_bulletplace2].ycord=-lendiry+agk::GetSpriteY(playanden[xxw].id)+ydistfromcenter+45;
		}
		else
		{
		playanden[xxw].g_Bullets[g_bulletplace2].xcord=lendirx+agk::GetSpriteX(playanden[xxw].id)+xdistfromcenter;
            
       playanden[xxw].g_Bullets[g_bulletplace2].ycord=-lendiry+agk::GetSpriteY(playanden[xxw].id)+ydistfromcenter;
		}
        playanden[xxw].g_Bullets[g_bulletplace2].angle=rotangle2;
		playanden[xxw].g_Bullets[g_bulletplace2].fLife=0.0f;
        playanden[xxw].g_Bullets[g_bulletplace2].bActive=true;
		g_bulletplace2++;
	
            //	agk::Print(g_bulletplace);
         if(g_bulletplace2==79)
         {
            g_bulletplace2=0;
         }
	}
	
}

Go through yourself at a wall.

Back to top

Profile PM Email Website

DennisW

15

Years of Service

User Offline

Joined: 15th Jun 2008

Location: Ohio

Posted: 30th Nov 2011 20:47

Link

@ Jerico2day
Thanks starting to make sense. Going to need a pot of coffee

Thanks to all

Dennis

Ham and Eggs Breakfast
The Chicken was involved the Pig was Committed

Back to top

Profile PM Email Website

baxslash

Valued Member

Bronze Codemaster

17

Years of Service

User Offline

Joined: 26th Dec 2006

Location: Duffield

Posted: 30th Nov 2011 21:23

Link

Just to add to J's help, if you are using an aspect rather than a set resolution size you'll need to multiply the Y value by an aspect ratio before using any of the sine rules IE

+ Code Snippet

aspect# = w#/h#
Yforce = speed * aspect# * Sin(angle)

Back to top

Profile PM Email

Sorry your browser is not supported!

AppGameKit Classic Chat / firing turret angle help