This was tested by replacing the node 0 scale in BusterDrone with
[-1, 1, 1].
For future reference, commit f728776 shows when we switched from
transpose(inverse()) to cof(). This was a good change, but before that
particular change, we had a "two wrongs made a right" situation for
mirrored normals.
Fixes#3001.
This significantly improve the depth-buffer resolution utilization
through the near-infinity range on Metal and Vulkan.
On OpenGL, this benefit is only seen when glClipControl is available.
The user-facing clip plane is unchanged [-1,1], the conversion
happens in filament's vertex shaders.
The bulk of this change consists in:
- invert the clip space's z in the vertex shader
- clear the depth buffer with 0
- invert all depth function comparisons
- fix all screen-space effects, e.g. ssao, DoF
- fix shadows and shadow biases
- use floating-point depth
- add a driver API to query which clip-space is used
- add glClipControl support to the gl backend
This is more similar to the Vulkan shader pipeline and less magical.
There are 3 places in our shader code where we perform fixups like this:
- main.vs
- depth_main.vs
- post_process_getters.vs
That last one needs no change since it does not involve Z.
This fixes dynamic lighting and SSAO when a viewport is not in 0,0.
In practice this currently happens only when all post-processing is
disabled.
Instead of using gl_FragCoord we introduce a new API,
getNormalizedViewportCoord(), which as the name implies returns
normalized [0, 1] viewport coordinates with origin at the bottom-left,
on all platforms.
This is implemented in this PR by interpolating gl_Position.
* Add support for bent normals
Bent normals can be enabled via the bentNormal property of a material.
When specular occlusion is enabled, bent normals improve the quality
of the computation.
* Save a couple of multiplications in bent specular AO
* Add the ability to modify clip space coordinates in the vertex shader
This introduces MaterialVertexInputs.clipSpaceTransform, a mat4 that
is applied to gl_Position before exiting the vertex stage.
* Address code review comments
This works by aliasing CUSTOM0 - CUSTOM7 to morphing attributes, and by
extending our existing skinning variant.
This PR was tested against some upcoming changes to gltfio.
Issue #1149, #1417
This replaces the previous "curvature to roughness" method. Both are related
and rely on the screen space variance of geometric normals but this new
solution offers more control (the screen space variance and the clamping
threshold can be controlled).
Recall that Vulkan has a right-handed NDC system. Currently, our Vulkan
backend is not handling VERTEX_DOMAIN_DEVICE correctly, but we didn't
notice because the culling mode is not honored yet (a separate PR is on
the way for that).
To fix this, we considered adding a shader-based fixup only for the
device domain and keeping our Vulkanish projection matrix as-is.
However, this would cause the skybox shader to compute an incorrect
wrong eye vector due to in the inconsistent definition of clip space.
After discussion with Mathias and Ben, we decided that the most elegant
fix is for Filament to have only one canonical clip space, which for
now is the clip space that OpenGL requires.
Ben pointed out that spirv-cross has a flag for injecting shader-based
fixups. However we don't invoke spirv-cross for the Vulkan target, and
it's easy just to do this on our own.
This is achieved by pre-scaling the normals
transform so that the resulting normal doesn't have
any large component allowing to do the normalize()
in the fragment shader in mediump.
This must be done for skinning too.
* Add clear coat normal map support
This change allows to set a separate normal map for the clear coat layer of a material.
* Document the new clearCoatNormal property
* Fix typo
