- add the use of DRWShaderLibrary to EEVEE's glsl codebase to reduce code
complexity and duplication.
- split bsdf_common_lib.glsl into multiple sub library which are now shared
with other engines.
- the surface shader code is now more organised and have its own files.
- change default world to use a material nodetree and make lookdev shader
more clear.
Reviewed By: jbakker
Differential Revision: https://developer.blender.org/D8306
Try to never do operation twice and try to use MADD operations. Even if this
is very unlikely to make any difference, it can help compilers do some
optimization. I did not measure any difference as probes have much higher
impact on render time because of texture lookups.
Note that disk light is currently the most expensive light type so it
does not hurt to micro optimize.
Main change are:
- the fresnel LUT is separated from the main GGX LUT.
- LUTs use sqrt(1.0 - NV) as roughness remapping. Improving precision and
removes needs for acos().
- LTC LUT is normalized by matrix middle component. Improving precision.
Sun is treated as a unit distant disk like in cycles.
Opti: Since computing the diffuse contribution via LTC is the same as not using the Linear Transformation, we can bypass most of the LTC code.
This replaces the sphere analytical diffuse computation as it gives a more pleasing result very close to cycles' AND cheaper.
Lights power have been retweaked to be coherent with cycles (except sun lamp with large radius where cycles has a non-uniform light distribution).
This is an improvement on the old spining quad method that was giving artifacts when the reflection ray was nearly aligned with the sphere center.
This might be a bit heavier but it's worth it.
Separate material handling inside another file.
Make use of enums to identify shader variations.
Group all 64*64 LUTs into one array texture.
Only update world probe if world changes.
For now only compute GGX convolution. The GGX LUT used for the split sum approximation (UE4) is merged with the LTX mag LUT that uses the same parameters (theta and roughness)
Using Linear Transform Cosines to compute area lighting. This is far more accurate than other techniques but also slower.
We use rotating quad to mimic sphere area light. For a better approximation, we use a rotating octogon.
