cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   SDKTutor
   Member

   I am creating a game where I need to use this code to shoot 360 degrees. Here is what I have so far:
   

   UITouch *myTouch = [touches anyObject];
   				CGPoint touchPoint = [myTouch locationInView:[myTouch view]];
   				touchPoint = [[CCDirector sharedDirector] convertToGL:touchPoint];
   				CCSprite *projectile = [CCSprite spriteWithFile:@"bullet.png" rect:CGRectMake(0, 0, 37, 37)];
   				projectile.position = ccp(240, 160);
   				[self addChild:projectile];
   				projectile.scale = .2;
   
   				int offX = touchPoint.x - projectile.position.x;
   				int offY = touchPoint.y - projectile.position.y;
   				int realX = 498;
   				if (offX <= 0) {
   					realX = -10;
   				}
   				float ratio = (float) offY / (float) offX;
   				int realY = (realX * ratio) + projectile.position.y;
   				if (realX == -10) {
   					realY = (-realX * -ratio) + projectile.position.y;
   				}
   				CGPoint realDest = ccp(realX, realY);
   				NSLog(@"%0.2f %0.2f", realDest.x, realDest.y);
   
   				// Determine the length of how far we're shooting
   				int offRealX = realX - projectile.position.x;
   				int offRealY = realY - projectile.position.y;
   				float length = sqrtf((offRealX*offRealX)+(offRealY*offRealY));
   				float velocity = 480/1; // 480pixels/1sec
   				float realMoveDuration = length/velocity;
   
   				// Move projectile to actual endpoint
   				[projectile runAction: [CCMoveTo actionWithDuration:realMoveDuration position:realDest]];

   So this is my problem. It works just fine if the touch point is to the right of bullet, but if it is too the left, it shoots straight left. How do I fix it so I can shoot a full 360 degrees.

   Posted 2 years ago #
2. 

   mobilebros
   Moderator

   This may be a stupid question but why all the craziness? You have offX and offY that calculate the vector between the two points. But then you set realX to -10 if offsetX is negative, aka if touch pt is to the left of the projectile. You then calculate the slope of the vector (ratio). You then set realY to what actually turns out to be the y value of projectile's position, BUT THEN if realX was indeed set to -10 then realY gets set again to the SAME value (-realX*-ratio = realX*ratio). Now having realX, and realY as your final result you then calculate the duration; correctly it seems.

   Why all that? Why not:

   ccTime d = ccpLength(ccpSub(touchPoint, projectile.position))/(480/1);
   [projectile runAction: [CCMoveTo actionWithDuration:d position:touchPoint]];

   Probably if you took out both if blocks, it might work... maybe.

   Posted 2 years ago #
3. 

   SDKTutor
   Member

   That code won't work because it needs to work on the basis of how a bullet works. It needs to shoot forever not just go to a spot where you clicked. I need it to shoot off screen not just go to the point.

   Posted 2 years ago #
4. 

   SDKTutor
   Member

   Anyone know how to do shooting? or know how to fix this code?

   Posted 2 years ago #
5. 

   Codemattic
   Moderator

   Why are you using ints at all? It seems like everything should be floats.

   What is the point of this?
   

   if (offX <= 0) {
    realX = -10;
   }

   Posted 2 years ago #
6. 

   SDKTutor
   Member

   The point of that is that it is set to 490 or something like that in the first place so that it goes to the right not the left, so you have to set it to a point on the left side.

   Posted 2 years ago #
7. 

   eoin
   Member

   OP, it would be easier for you to use the debugger and see what is up, our option is to eyeball the code. This is really a bug in yout code, not Cocos2d.

   I am not sure what you mean by a 360 degree bullet shoot anyway.

   ( Also, the stlye in the code could do with a cleanup).

   Posted 2 years ago #
8. 

   SDKTutor
   Member

   Ok I finally got it to work. If you are wondering how I did it, this is how:
   `
   UITouch *myTouch = [touches anyObject];
   CGPoint touchPoint = [myTouch locationInView:[myTouch view]];
   touchPoint = [[CCDirector sharedDirector] convertToGL:touchPoint];
   [c setR: CC_RADIANS_TO_DEGREES(-ccpToAngle(ccpSub(touchPoint, c.position))) withPoint:touchPoint];
   CCSprite *projectile = [CCSprite spriteWithFile:@"bullet.png" rect:CGRectMake(0, 0, 37, 37)];
   projectile.position = ccp(c.position.x, c.position.y);
   [self addChild:projectile];
   projectile.scale = .2;

   int offX = touchPoint.x - projectile.position.x;
   int offY = touchPoint.y - projectile.position.y;
   int realX = 490;
   if (offX <= 0) {
   realX = -490;
   }
   float ratio = (float) offY / (float) offX;
   int realY = (realX * ratio) + projectile.position.y;
   CGPoint realDest = ccp(realX, realY);
   NSLog(@"%0.2f %0.2f", realDest.x, realDest.y);

   // Determine the length of how far we're shooting
   int offRealX = realX - projectile.position.x;
   int offRealY = realY - projectile.position.y;
   float length = sqrtf((offRealX*offRealX)+(offRealY*offRealY));
   float velocity = 480/1; // 480pixels/1sec
   float realMoveDuration = length/velocity;

   // Move projectile to actual endpoint
   [projectile runAction:[CCSequence actions: [CCMoveTo actionWithDuration:realMoveDuration position:realDest], [CCCallFuncN actionWithTarget:self selector:@selector(remove:)],nil]];
   // i added the callfunc method but that doesn't really made a difference
   ~

   Posted 2 years ago #
9. 

   mobilebros
   Moderator

   You just wanted it to go until it went offscreen?

   CGPoint n = ccpNormalize(ccpSub(touchPoint, projectile.position))
   CGPoint realPoint = ccpAdd(projectile.position, ccpMult(n, 260));
   ccTime d = 260/480;
   [projectile runAction: [CCMoveTo actionWithDuration:d position:realPoint]];

   This gets the direction, selects the correct point 260 units away and good to go.

   Posted 2 years ago #
10. 

    SDKTutor
    Member

    That's a much more efficient way of doing it. Thanks!

    Posted 2 years ago #

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