OpenGL: Unconditionally set glFrontFace

Previously glFrontFace was called only if some cull mode was set. This
was incorrect because the front face also influences whether a triangle
uses stencilFront or stencilBack.

Because OpenGL default to GL_CCW (which with the Y-flip is the inverse
of wgpu::FrontFace::CCW that's default in the descriptor), if
stencilFront != stencilBack and cull mode is none, then the incorrect
stencil face descriptor was used.

Also adds a regression test for this issue.

Bug: dawn:508
Change-Id: I00d93bda6d4f030cf9db472a9f2b0deefc72707f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/26880
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
This commit is contained in:
Corentin Wallez
2020-08-18 12:30:06 +00:00
committed by Commit Bot service account
parent d95180dede
commit 7268e7d36f
2 changed files with 18 additions and 4 deletions

View File

@@ -43,14 +43,15 @@ namespace dawn_native { namespace opengl {
void ApplyFrontFaceAndCulling(const OpenGLFunctions& gl,
wgpu::FrontFace face,
wgpu::CullMode mode) {
// Note that we invert winding direction in OpenGL. Because Y axis is up in OpenGL,
// which is different from WebGPU and other backends (Y axis is down).
GLenum direction = (face == wgpu::FrontFace::CCW) ? GL_CW : GL_CCW;
gl.FrontFace(direction);
if (mode == wgpu::CullMode::None) {
gl.Disable(GL_CULL_FACE);
} else {
gl.Enable(GL_CULL_FACE);
// Note that we invert winding direction in OpenGL. Because Y axis is up in OpenGL,
// which is different from WebGPU and other backends (Y axis is down).
GLenum direction = (face == wgpu::FrontFace::CCW) ? GL_CW : GL_CCW;
gl.FrontFace(direction);
GLenum cullMode = (mode == wgpu::CullMode::Front) ? GL_FRONT : GL_BACK;
gl.CullFace(cullMode);