cocos2d for iPhone

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

1. 

   ScaredOfTheInternet
   Member

   Hey all. I was wondering if there was any go to solution for drawing anti aliased polygons (in particular circles/rectangles. I have looked extensively through the documentation, and it appears that with the advent of OpenGl 2.0, there is very little native support for anti aliasing in things that aren't textures. I am currently using ccDrawingPrimitive::drawSolidPoly for this purpose, but the aliasing is just way too noticeable.

   Does anyone have any ideas on where to go with this? I was thinking that maybe I apply a shader to it or something, but it seems a little extreme for what I imagine must be a common problem. I really love the speed of ccDrawingPrimitives (which is important to me), but it is surprising to me that there is no way to enable anti-aliasing.

   Posted 11 months ago #
2. 

   slembcke
   Administrator

   HMVectorNode -> http://www.cocos2d-iphone.org/forum/topic/32770

   It does very high quality shader based anti-aliasing and draws batched, anti-aliased lines, circles and polygons. It's a little limited right now in terms of fill/stroke options, but it works quite well.

   I haven't released the current source separate from one of my other projects (yet), but you can grab the latest version out of the Space Patrol example project.
   https://github.com/slembcke/SpacePatrol

   The issue is that GL doesn't really provide reliable support for anti-aliased primitives. You can enable multi-sampling, but that generally produces ugly artifacts on lines. So it's really up to the developer to figure out how to provide unless you can can live with aliasing.

   Posted 11 months ago #
3. 

   ScaredOfTheInternet
   Member

   Thanks for the prompt reply! I'm not sure that the HMVectorNode is the solution I'm looking for, but maybe it's because of my unfamiliarity with its code base (especially because I'm using Box2D, not chipmunk.)

   So what I'm actually doing is using CCDrawPrimitives to render polygons to a CCRenderTexture. When I do this using HMVectorNode, nothing draws. Here is my code:
   

   - (void)constructPolygon:(const CGPoint *)poly numPoints:(NSUInteger)numberOfPoints red:(float)red
   {
       [self.maskTexture begin]; //CCRenderTexture I render to
   
       ccColor4F color = {red, 0, 0, 1};
       ccColor4F colorStroke = {1,1,1,1};
   
       //self->pr is the HMVectorNode
       [self->pr drawPolyWithVerts:poly count:numberOfPoints width:1 fill:color line:colorStroke];
       [self->pr draw];
   
       //I initially used this instead.
       //ccDrawSolidPoly(poly, numberOfPoints, color);
   
       [self.maskTexture end];
   }

   I definitely recognize that this is unorthodox, this was just for testing purposes. I don't add the HMVectorNode to the children of the parent because I don't want it rendering itself every frame. I just want to draw these polygons to the rendertexture. The expected output is the same polygon I had before, but anti aliased. The actual output is nothing. I actually save the rendertexture's texture to a file to see it, and it is blank.

   Posted 11 months ago #
4. 

   slembcke
   Administrator

   I think it's because you want to call visit instead of draw. That's how you would normally render individual nodes.

   Also, HMVector node doesn't really rely on Chipmunk. Actually, it shouldn't even require any other Chipmunk code in the project to operate.

   Posted 11 months ago #
5. 

   ScaredOfTheInternet
   Member

   Hmm, I tried replacing draw with visit, and still no rendering. Is it possibly just rendering in the wrong place? I give it an array of CGPoints where somewhere between (0,0) and (480,320) where (0,0) is the bottom left.

   The code currently stands at

   - (void)constructPolygon:(const CGPoint *)poly numPoints:(NSUInteger)numberOfPoints red:(float)red
   {
       [self.maskTexture begin];
   
       ccColor4F color = {red, 0, 0, 1};
       ccColor4F colorStroke = {1,1,1,1};
       [self->pr drawPolyWithVerts:poly count:numberOfPoints width:1 fill:color line:colorStroke];
       [self->pr visit];
      // [self->pr draw];
      // ccDrawSolidPoly(poly, numberOfPoints, color);
   
       [self.maskTexture end];
   }

   Posted 11 months ago #
6. 

   slembcke
   Administrator

   Hmm. Dunno. There shouldn't be anything special about invoking the vector node.

   This works for me:
   

   HMVectorNode *vnode = [HMVectorNode node];
   [vnode drawDot:cpv(128, 128) radius:50.0 color:ccc4f(1, 0, 0, 1)];
   //[self addChild:vnode z:1000];
   
   CCRenderTexture *rt = [[CCRenderTexture alloc] initWithWidth:256 height:256 pixelFormat:kCCTexture2DPixelFormat_RGBA8888];
   [rt beginWithClear:0 g:0 b:0 a:1];
     [vnode visit];
   [rt end];
   
   rt.sprite.anchorPoint = ccp(0, 1);
   
   [self addChild:rt z:1000];

   

   I suspect that you might just be rendering offscreen somehow? Also, I'm not sure what it would do if you passed it a concave polygon... I've never actually attempted to draw one. It should draw something, maybe just not what you expect though.

   Posted 11 months ago #
7. 

   ScaredOfTheInternet
   Member

   That's interesting that that works for you. I don't think I'm rendering it offscreen because I just copied your code directly and I don't even get anything on the render texture! One caveat that I have though, is that cpv doesn't exist for me, so I used ccp. Do you think that matters?

   Posted 11 months ago #
8. 

   ScaredOfTheInternet
   Member

   In fact, I made a new project in cocos2d and copied and pasted your code into the helloworldlayer that is autogenerated. It just creates a black box, no red circle in it!

   Posted 11 months ago #
9. 

   slembcke
   Administrator

   Hmm. So I'm using the GitHub version of Cocos2D and not an official release. That might have something to do with it.

   Chipmunk vectors are aliased to CGPoints on iOS and OS X by default. So cpv() is functionally equivalent to ccp() and CGPointMake().

   Posted 11 months ago #

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