Thanks to all replies but I was able to figure it out.
My initial idea was to modify a color attachment created in the first
pass in the second pass only where fragments were created(i.e. depth was
written)
I came up with the following solution:
1. Pass
RTT-Cam1
- DEPTH, COLOR1, COLOR2, ...
- renders the scene
2. Pass
RTT-Cam2
- DEPTH, COLOR1 (same attachments as in the first pass
- depth test to GREATER
- depth writes off
- disable color and depth clearing (which we want to reuse)
- bind the COLOR1-texture as uniform input
- render a full screen quad with camera in ABSOLUTE_RF and same
viewport as first pass
- in the frag shader for instance do: gl_FragData[0]=
vec4(texture2D(firstPassTexture,gl_TexCoord[0].st).rgb, 0.0) +
vec4(0.0,0.0,0.0, myNewTerm);
This works, because the fullscreen quad rendered will pass depth test
only if something was written there in the first pass. Using this sceme
saves us a stencil test.
There is a remaining question however:
What I really wanted to do is to write the gl_FragData[0].rgb in the
first and gl_FragData[0].a in the second pass.
This gave me a blank result (with the alpha component set to 1)
Do I have to enable blending or something? Or is it illegal to write
uncomplete FragData?
Hello,
I've have a question regarding RenderToTexture in a multipass setup.
I have to RTT cameras, the first one has DEPTH and 3 color
attachments, while the second has only one color attachment.
I need to use the data from the first RTT-pass in the second camera,
so the renderorder is set accordingly.
Basically my scene is organized like this:
root
|
RTTCamera_1
| |----Model
RTTCamera_2
| |----Model
Booth cameras use the same geometry, viewport, transform. Yet the
Model graph is culled twice.
Is there any way to prevent the second cull traversal? I.e. reuse the
batch collected in the first culling?
cheers
Sebastian
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