Is there a way to fetch PBR attributes and normals in a deferred fragment shader?

bac9-flcl

The title pretty much covers it.

I want to create an opaque per-pixel fragment shader that:

• Will be rendered after all normal opaque surfaces but before all transparent surfaces
• Will have albedo, specular, smoothness, occlusion values and normals fetched from the deferred render targets (for each given pixel)
• Will output those fetched RT values

Basically, this will make the shader completely invisible, as it will just write back the content of deferred render targets. This is the base I need to create proper UE4-like normal decals and some other stuff, but those are the easy part. What I need to figure out right now is how can I get that content from RTs. I'm unable to find anything about this in the documentation, but this should be possible - after all, Unity already offers a way to fetch values like linear eye depth, so asking to fetch something like smoothness is not exactly an exotic thing.

Can anyone help me out?

echofourpapa

Yes. Here's the layout:

sampler2D CameraGBufferTexture0 is diffuse(rgb)
sampler2D CameraGBufferTexture1 is Specular(rgb) and roughness(a)
sampler2D CameraGBufferTexture2 is world-space normals(rgb)
sampler2D CameraGBufferTexture3 is lighting(rgb)

Use those in any shader.

Docs here: http://docs.unity3d.com/Manual/RenderTech-DeferredShading.html

But you might find this more interesting: http://blogs.unity3d.com/2015/02/06/extending-unity-5-rendering-pipeline-command-buffers/

bac9-flcl

Thanks! Unfortunately, I have a few issues with those textures. Specifically:

- Those textures do are not sampled properly at all if my shader has no decal:add or decal:blend - I get a completely random surface texture within _CameraGBufferTexture0 and others if I attempt to read it from an ordinary opaque shader.

- Sometimes those textures jump around wildly or contain pure black, which to me suggests that the decal renders too early - but setting the queue/type to transparent does absolutely nothing to solve the issue. Only decal:add or decal:blend solve it, which makes me wonder what's so special about those attributes. Nothing out of ordinary is documented about them.

- If I do use decal:blend or decal:add, absolutely nothing I do in finalgbuffer function is seems to affect the surface, so I can not actually put the values I read from the buffers back into them, it seems. I suspect that happens because decal:add and decal:blend force my shader to go into forward mode, which is obviously not desirable at all. Maybe it's completely impossible to read those textures from a deferred shader and I should look for other approach to implementing normal decals.

As about command buffers, I looked at the example and I have to admit I was not able to understand anything useful out if it. I need a far, far more simple thing - a surface shader for geometry that already has proper placement and UV mapping. The example is filled with code handling projection, boxes, keeps per-decal object references, does strange blit operations in a special component and so on, which makes it really hard to understand how to apply it to a simple surface decal shader. For reference, I'm trying to replicate a shader similar to these from UE4 and CE: http://www.polycount.com/forum/showthread.php?t=155894