kc3-lang/angle

2019-11-21T10:13:44

Metal: fix vertex attribute's conversion lost after changing buffer binding. After vertex buffer's attribute is converted and stored in conversion buffer. Binding the same attribute to another buffer, then binding it back to previous buffer will result in previous conversion information lost. The conversion method would skip the conversion due to buffer's content hadn't been changed, however it didn't reuse the old conversion result. This CL also changed the way binding offset is used in Metal backend. - Previous, the offset would be assigned to the offset field of MTLVertexAttributeDescriptor, then the buffer would simply be bound to the command encoder with offset=0 i.e. setVertexBuffer(buffer, index, 0) - However this approach has several disadvantages. Since Metal doesn't allow MTLVertexAttributeDescriptor's offset to be larger than the vertex attribute's stride, the old approach would force the back-end to convert the attribute and store in conversion buffer. New approach: - MTLVertexAttributeDescriptor's offset will be zero. The offset will be used to bind the buffer itself to the render command encoder. i.e. setVertexBuffer(buffer, index, offset) This way the "offset <= stride" restriction no longer exists. The only restriction is the offset must be multiple of attribute's size. Added 3 new tests: - SimpleStateChangeTest.RebindTranslatedAttribute - VertexAttributeTest.DrawWithLargeBufferOffset - VertexAttributeTest.DrawWithLargeBufferOffsetAndLessComponents Bug: angleproject:2634 Change-Id: I6c2fa8091436e4a24405d791f86d17d97df02d64 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1940009 Commit-Queue: Jonah Ryan-Davis <jonahr@google.com> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>