Z-sorting Bug

[Andy Gilbert]

Ive had a quick look through the bugs but cant find a report for this (could have missed it though), there is also a possibility this isnt a bug but i cant figure a way around it.

 

If i have a model and mat with an alpha, the "alpha" part seems to only let CSG stuff though and not other models through, if i move the camera around sometimes they appear other times they dont.

 

Thanks

Andy

[Josh]

There is a z-sorting option in the material settings.

[Andy Gilbert]

Im aware of that, and rightly so that does sort the transparency, it doesnt however fix the bug mentioned above.

 

Andy

[Josh]

I need an example so I can recreate this problem.

[Andy Gilbert]

Okay ill try put one together, what do you need exactly?

 

Here is a screen shot aswell.

 

 

Andy

[Josh]

So you have multiple layers of alpha blending? Set the depth mask to 0. Beyond that, I can't tell without an actual example I can run.

[Andy Gilbert]

Set the depth mask to 0. Beyond that, I can't tell without an actual example I can run.

 

Can this be done in the editor? I asked previously what actual files do you need, map, models, whole project?

 

Andy

[Josh]

I need all the files necessary to actually produce the problem on my own computer.

[Andy Gilbert]

Files sent via PM.

 

Andy

[Josh]

The problem is you have multiple layers of alpha blending within one surface, and z-sorting does not work on a per-polygon basis. We normally use alpha masking for vegetation, not alpha blending.

• It's faster to render.
  
• It avoid z-sorting issues like this.
  

Disable z-sorting in your material. Set the blend mode to solid.

 

You then need a shader that does a discard if the alpha value is below 0.5. You can copy the shader you are using, then add this in the fragment shader source:

//Modulate blend with diffuse map
outcolor *= texture2D(texture0,ex_texcoords0);
if (outcolor.a<0.5) discard; // ADD THIS LINE

 

I will add some more shaders into the official SDK soon, including one for this purpose.

 

Leadwerks 2 had an alpha mask setting, but we no longer support this because the functionality was dropped in OpenGL 3.2+. It's supposed to be done with a shader, now, and we want to be future proof.