cocos2d for iPhone

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

1. 

   ddeaco
   Member

   Hi,

   I'm currently using a negative vertexZ property on batched CCSprites to give a quick and easy parallax/depth effect. I then scale the sprite up so they don't become really small.

   When rendering the scene to a texture using -
   

   CCRenderTexture *rendertexture = [CCRenderTexture renderTextureWithWidth:1024 height:1024];
   
   [rendertexture begin];
   [self visit];
   [rendertexture end];

   When the texture is rendered, all the sprite's vertexZ property seems to return to default.

   All sprites that haven't had their vertexZ property modified appear as expected.

   I'm not changing the camera in anyway. I'm currently using 0.99.5, I have checked the 1.0rc/beta change logs and didn't see anything covering this possible issue.

   Is this the correct behavior?

   Thanks David.

   Posted 1 year ago #
2. 

   araker
   Moderator

   This is a rare requirement. VertexZ needs a depth buffer and the off-screen buffer from the render texture doesn't allocate one. That's why it won't work. One work around is to sort the sprites you're visiting from back to front to get the right drawing order.

   Posted 1 year ago #
3. 

   ddeaco
   Member

   Thanks for the info araker, I already tried you suggestion but it still doesn't get me round the problem of the scaling that have negative vertexZ.

   Do you have any idea if it's possible to modify the render texture class to allocate the buffer and solve the problem?

   Posted 1 year ago #
4. 

   araker
   Moderator

   Are you using a perspective projection? In that case you'll need to set that as well.

   It wouldn't be much work to get the changes done, It can be a bit tricky though.
   When you subclass CCRenderTexture..
   -initialize the depth buffer in the init (do it exactly like in the ES1Renderer). Make sure to save the index of the other depth buffer.
   - change the projection in the begin method and bind the new depth buffer there as well
   - bind the other depth buffer in the end method

   Posted 1 year ago #
5. 

   ddeaco
   Member

   I'm struggling to fix this my self, so I've made a test case.

   XcodeProject-
   http://dl.dropbox.com/u/514219/vertexZTest.zip

   Basically all the sprites positions are the same, click drag to move them. As you can see they have depth because of the vertexZ value.

   When the touch ends a CCRenderTexture is setup and displayed on screen with a green tint.

   As you can see from the screen shots below the resulting texture doesn't line up with the original scenes projection. But anything with vertexZ value of 0 does.

   Also notices that the end yellow sprite is scale up but in the resulting CCRenderTexture its been scaled back down...

   If you go into the app delegate and set the directors projection to kCCDirectorProjection2D you lose the parallax effect and everything renders as you would imagine.

   http://dl.dropbox.com/u/514219/vertexZtest01.jpg

   http://dl.dropbox.com/u/514219/vertexZtest02.jpg

   I cant be the only person using vertexZ, it would be cool if we could get this fixed before 1.0.

   Any help would be much appreciated.
   David

   Posted 11 months ago #
6. 

   riq
   Key Master

   @ddeaco:

   Yes, it seems that CCRenderTexture has a bug.
   It is using a 2d projection, and I'm not sure why.

   Try to replace the CCRenderTexture#begin method, with this one
   

   -(void)begin
   {
   	// issue #878 save opengl state
   	[self saveGLstate];
   
   	CC_DISABLE_DEFAULT_GL_STATES();
   	// Save the current matrix
   	glPushMatrix();
   
   //	CGSize texSize = [texture_ contentSizeInPixels];
   //
   //	// Calculate the adjustment ratios based on the old and new projections
   //	CGSize size = [[CCDirector sharedDirector] displaySizeInPixels];
   //	float widthRatio = size.width / texSize.width;
   //	float heightRatio = size.height / texSize.height;
   //
   	// Adjust the orthographic propjection and viewport
   //	ccglOrtho((float)-1.0 / widthRatio,  (float)1.0 / widthRatio, (float)-1.0 / heightRatio, (float)1.0 / heightRatio, -1,1);
   //	glViewport(0, 0, texSize.width, texSize.height);
   
   	glGetIntegerv(CC_GL_FRAMEBUFFER_BINDING, &oldFBO_);
   	ccglBindFramebuffer(CC_GL_FRAMEBUFFER, fbo_);//Will direct drawing to the frame buffer created above
   
   	CC_ENABLE_DEFAULT_GL_STATES();
   }

   It is like the original, but with glOrtho() and glViewport() commented.

   Please, try it, and let me know if it works OK. Thanks.

   Posted 11 months ago #
7. 

   ddeaco
   Member

   Perfect! works in both 2D and 3D projection modes!

   Posted 11 months ago #
8. 

   riq
   Key Master

   I won't be able to merge this patch into 1.0 since it is breaking the RenderTexture test... and I don't know why yet.
   So, if the patch works OK for you, use it. But just take into account that it breaks other stuff.

   BTW, I would like to include your test as part of the RenderTexture Test suit. Do I have your permission to add it ? Thanks.

   Posted 11 months ago #
9. 

   ddeaco
   Member

   Yeah sure, does that mean i get to go on the contributors list(for a tiny tiny part)? :D

   Posted 11 months ago #
10. 

    riq
    Key Master

    @ddeaco: yes :)

    Posted 11 months ago #

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