[SOLVED]Occlusion errors with quake map and transparency

[SuperElectric]

I've loaded a quake level with some trees in it, where the leaves are just textures painted on two crossed billboards. At first the billboards were showing up as black squeares with leaf textures, since the materialType was being set to EMT_SOLID. I made the following change in CQ3LevelMesh.cpp:

Code: Select all

if (!b->Material.Texture2){
   // replaced this line...
   //b->Material.MaterialType = video::EMT_SOLID;
   // with this line:
   b->Material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
}

Outside of CQ3LevelMesh.cpp, I turned the backface culling off for the quake map's SceneNode, so the leaf node textures would show up from both sides.

Now there's a new problem. The mountains in the background seem to occlude the leaf textures in the foreground. This didn't happen before I changed everybody's material type. Turning off the back face culling doesn't seem to be the problem. I tried turning it back on and the problem persisted.

Here's a screen shot of the scene before I changed the MaterialType:


Here's the same scene with everybody's material type changed to video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF:


Notice how the brown mountains are now occludig the tree leaves.

I'm using version 0.10.0. This occlusion problem didn't happen in 0.9, when I was using ZDimitor's patch (link) for transparency.

Any idea why this could be happening? Any suggestions on what I could try to narrow down source of the problem would be appreciated.

Thanks,
-- Matt

[SuperElectric]

For what it's worth, using EMT_TRANSPARENT_ALPHA_CHANNEL doesn't cause this problem; just EMT_TRANSPARENT_ALPHA_CHANNEL_REF.

[don_Pedro]

I think it's a bug in EMT_TRANSPARENT_ALPHA_CHANNEL_REF under OpenGL. In COpenGLMaterialRenderer.h, COpenGLMaterialRenderer_TRANSPARENT_ALPHA_CHANNEL_REF::OnSetMaterial(...) should be deleted line

Code: Select all

material.ZWriteEnable = false;

[SuperElectric]

Awesome; that seems to have fixed it.

Thanks!
-- Matt