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Hash : 93560ef5
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Date : 2019-07-25T16:13:02
Vulkan: Seamful cube map emulation In GLSL, a cube texture is sampled with one of textureCube* functions. This function takes a 3D coordinate which is a vector from the center of the cube and identifies a direction to sample from. GLES2.0 has the following table that translates this 3D coordinate (Rx, Ry, Rz) to a face and ST coordinates within that face. This table can be found in Section 3.7.5 (Cube Map Texture Selection). A compiler pass is implemented in ANGLE that replaces samplerCube declarations with a sampler2DArray. The textureCube* functions are replaced with the corresponding texture* functions with the translated coordinates according to that table. Gradients provided to textureCubeGrad are translated using the same formulae, which is not precise but the spec specifies this projection to be implementation dependent. Helper invocations enabled through WQM (whole quad mode) cause a nuisance in that the extrapolated varyings used as coordinates in a textureCube call could have a different major axis (and therefore face) from the non-helper invocations that lie within the geometry. subgroupQuadSwap* operations are used in conjunction with gl_HelperInvocation to make sure the helper threads calculate texture UVs in the same face as the non-helper invocations. Bug: angleproject:3300 Bug: angleproject:3240 Bug: angleproject:3243 Bug: angleproject:3732 Change-Id: I0cb6a9b1f2e1e6a392b5baca1c7118ed1c502ccf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1715977 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
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Files
- ShaderLang.h
- ShaderVars.h
