Mirror reflection & deferred shading

Questions & Answers
1

Hi all,

I've been using the MirrorReflection script+shader from Unify, and it worked pretty good until I switched to deferred rendering. Now it seems the objects are not lit anymore (except for the ambient?) in the reflection image. Any idea why? Note that :

  • I've force-enabled the "use pixel lights" in the script
  • I've got a couple of other render-to-texture which do work with deferred rendering

Thanks,

Ben

3

Just to document the technical reason for this issue:

Deferred rendering calculates the world-position as part of lighting the scene. This calculation is based on the depthbuffer of the rendered scene.

The reflection camera uses an oblique projection matrix - skewing the viewfrustum of the reflection-camera in order to create a clipplane at water-level.

As a result, the depth from a reflection cam, is different to the depth of a regular cam, causing wrong positions to be used in the deferred lighting calculations. This causes similar issues with shaders that use the depthbuffer in their rendering as well - e.g. soft-particles, and various post-effects.

A solution would be to use the inverse projection-matrix for depth-reconstruction, but this would make all lighting-calculations in Unity slower.

So far, the best solution is probably to use the forward rendering, and just reduce the number of objects reflected to account for the reduced performance.

2

Try this dirty hack:

reflectionCamera.renderingPath = RenderingPath.Forward;

I don't know why there is no way to render reflections with Deferred Lighting ((