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cocosboy
Member
Hi,
I need to make a shape as user drags finger on iPhone the application will draw a line. when the user stops the dragging finger on the point from where the user started dragging the shape will close. This any shape can be destroyed if any body collides with it..
any idea to do that...
thanks in advance
Here is one possible way of doing the drawing part (maybe not the best way). Sorry this is quick and dirty pseudo code I just kind of came up with on the spot.
Make an array of CGPoints that collects the first point as the user starts touches and collects each point additional point as the user drags their finger.
In your draw method, while user is touching,
For each point in the array do a drawLine(lastCGPoint, currentCGPoint) call (Check out the Draw Primitives test, as there are a couple other calls to gl for setup).
Then on touches end, take the first and last point in the array and use them to calculate a rect.
Draw the rect and then flush the array (if you want users to be able to touch and draw again).
The collision detection and destroying could be done by saving this rect as a global placeholder object and having a scheduler check constantly if this rect and all other objects intersect. If they do, clear the rect (stop drawing it) and do game logic for a collision?
Hope it helps you out!
cocosboy
Member
Then on touches end, take the first and last point in the array and use them to calculate a rect. Draw the rect and then flush the array
Actually it will be an irregular shape and I don't want draw a rectangular box around it like this for collision purpose 
(if you mean to say that).
after drawing I want it to save some where and redraw on the game play scene to use. Its shape will not be affected later once drawn.
One thing more while game play I need to zoom in and zoom out the view so that the size of this shape will change.
and whenever an other body collides with them they will destroy(not as a whole only the place of collision)
Sorry I may not be able to clear what I wanted on start. if some one wish i can explain more.
I am new to cocos2d
thanks for reply
rickms
Member
Only problem with this is box2d/chipmunk requires shapes to be CONVEX. The only way to get more complicated shapes is to use compound shapes, so unless you are going to validate that the drawn shape is indeed convex, this adds a whole new layer of complexity to what you want to do.
Edit:This all assumes you are using a box2d/chipmunk of course, if it is strictly cocos2d, I apologize.
cocosboy
Member
Actually what i have done is
I am drawing Sprite point(5x5) on each touch point while movement. using the code
- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
for(UITouch *touch in touches )
{
CGPoint location = [touch locationInView: [touch view]];
location = [[CCDirector sharedDirector] convertToGL: location];
[self DrawAPointOnPos: location.x y:location.y];
}
}
-(void) DrawAPointOnPos: (float)x y:(float)y
{
int posx, posy;
CCSpriteSheet *sheet = (CCSpriteSheet*) [self getChildByTag:kTagAtlasSpriteSheet];
CCSprite *sprite = [CCSprite spriteWithSpriteSheet:sheet rect:CGRectMake(posx, posy, 5, 5)];
[sheet addChild: sprite];
sprite.position = ccp(x,y);
}
It draws a Sprite point while we are moving finger on iPhone screen, that makes any shape according to dragged finger, for collision the small points of 5x5 sprite can be used and can be destroyed.
In this way we can draw 2 or 3 shapes on screen... that need to be stored some where and will be displayed on the game play screen usage.
you may think that a shape can contain more than 100 sprites. I wish to know
Is that right way to achieve it what I am willing to?
and will I be able to zoom in and zoom out for such shapes on game play?
thanks for reply
robodude666
Member
Hey,
I'd recommend you checkout my RDDrawingSprite class I released a few days ago:
http://www.cocos2d-iphone.org/forum/topic/7038#post-41346
It gives you the ability to draw lines within a sprite. You can manually draw lines, or pass in an array of CGPoints which get connected. It's not a fully featured class, but it works for basic needs. Cocos2D can support about 20 or so of these RDDrawingSprites before frames start to drop.
-robodude666
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