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Index › Programming Questions & Help › Syntax Questions › Depth sorting at will
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Depth sorting at will (Read 1046 times)
mkn
Depth sorting at will
Jul 8th, 2007, 8:04pm  
Hey all,

Anybody got a clue how to mix 3D and 2D and still be in control? I can't figure out how to turn on and off depth sorting per frame. Simplified, what I want to do is this:

Code:

// let processing take care of polygon sorting
hint(ENABLE_DEPTH_SORT);

//clear screen
background(255);
// disable depth checking here
image(bgImg, -bgX, -bgY);
// enable depth checking here
pushMatrix();
// do wicked stuff
   ... 
popMatrix();
// disable depth checking again here
image(onTopImg, guiX, guiY);


The reason why I want to escape perspective is because the images are pretty big and I don't want to have them rescaled for every frame. Also, background(PImage) is also no good because I want to move the images around.

Tried with various hint():s, g.begin/endDraw(), clearing the zbuffer and even fiddeling with camera settings and switching between ortho() and perspective() and of course searching the forums.

Any advice appreciated.

Mkn.
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V
Re: Depth sorting at will
Reply #1 - Jul 9th, 2007, 11:11am  
im not sure how does processing handles it to you, i do the opengl calls as:


GL opengl;


setup:
 opengl = ((PGraphicsOpenGL)g).gl;


mainloop:
 opengl.glDisable( GL.GL_DEPTH_TEST );
 opengl.glDepthMask( false );

hope that helps,
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Victor Martins | www.pixelnerve.com/v
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ewjordan
Re: Depth sorting at will
Reply #2 - Jul 10th, 2007, 9:22pm  
I think you may be confusing ENABLE_DEPTH_SORT with turning the z-buffer on and off - the depth sorting is only to arrange the draw order of polygons so that alpha blending works right with translucent polygons, and I don't think that is what you're looking for here.  Processing handles draw order on a first come first served basis unless ENABLE_DEPTH_SORT is flagged, using the z-buffer to handle occlusion and all that fun stuff.  As far as turning off the z-buffer checking, I'm not entirely sure, perhaps someone else knows what to do about this.
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fry
Re: Depth sorting at will
Reply #3 - Jul 10th, 2007, 10:04pm  
i think you're looking for hint(DISABLE_DEPTH_TEST).
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mkn
Re: Depth sorting at will
Reply #4 - Jul 11th, 2007, 2:21pm  
Hmm, its not what I'm looking for. Smiley

I mean, what I want to move around images in the background in their original size and then display 3d perspective stuff on top and then finally have a final layer or unresized bitmaps on top.

Something like:
Code:

background(255);

ortho();
moveAroundBackgroundBitmaps();

perspective();
clearZBuffer();
moveAround3DObjects();

ortho();
clearZBuffer();
drawGUIonTop();


I guess it could be done with off screen buffers for the 3D rendering, but that would only work in P3D. Also, I'd prefer not having to copy a lot of buffers with alpha channels every frame as the purpose is to preserve computational resourses to where its better needed.

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JohnG
Re: Depth sorting at will
Reply #5 - Jul 11th, 2007, 3:47pm  
You can clear the zBuffer manually:

P3D:
Code:

for(int i=0;i<((PGraphics3D)g).zbuffer.length;i++)
{
  ((PGraphics3D)g).zbuffer[i]=Float.MAX_VALUE;
}


OpenGL:
Code:

  gl.glClear(GL.GL_DEPTH_BUFFER_BIT);
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mkn
Re: Depth sorting at will
Reply #6 - Jul 11th, 2007, 4:07pm  
Ah!

Code:

Arrays.fill( ((PGraphics3D)g).zbuffer, Float.MAX_VALUE);


is probably even more efficient. Smiley

Brilliant. Thanks!
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