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[Fix] (State): start the clear colour at GL's (0, 0, 0, 0), not opaque black

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swung0x48
2026-10-02 12:50:36 -04:00
parent 258b946086
commit 8da082f805
2 changed files with 19 additions and 2 deletions
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MobileGL/MG_Pipe/MGPipeValueTypes.h
+4 -2
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@@ -304,8 +304,10 @@ namespace MobileGL {
Bool DepthClampEnabled = false;
Bool TextureCubeMapSeamlessEnabled = false;
// Clear State
FloatVec4 ClearColor = FloatVec4(0.0f, 0.0f, 0.0f, 1.0f);
// Clear State. GL's initial clear colour is (0, 0, 0, 0) (GL 4.6 core table 23.24): an
// application that never calls glClearColor - or caches it and skips the redundant call -
// clears to transparent, and offscreen layers depend on it.
FloatVec4 ClearColor = FloatVec4(0.0f, 0.0f, 0.0f, 0.0f);
Float ClearDepth = 1.0f;
Uint32 ClearStencil = 0;
FloatVec4 BlendColor = FloatVec4(0.0f, 0.0f, 0.0f, 0.0f);
MobileGL/MG_Test/State/RenderStateTest.cpp
+15
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@@ -645,6 +645,21 @@ TEST_F(RenderStateTest, TheFirstScissorWriteBumpsTheVersionEvenWhenTheValueDoesN
// were absent too, which is what KHR-GL4x.tessellation_shader.single.
// default_values_of_context_wide_properties dies on.
// GL 4.6 core table 23.24 / ES 3.2 table 21.13: GL_COLOR_CLEAR_VALUE starts at (0, 0, 0, 0). An
// opaque-black default made every glClear of an application that relies on the initial value -
// a layer that caches GL state and skips the redundant glClearColor(0, 0, 0, 0) - write alpha 1,
// so offscreen layers meant to be transparent composited as solid black squares.
TEST_F(RenderStateTest, ClearColorStartsAtTransparentBlack) {
const SharedPtr<MG_State::GLState::GLContext> previous = MG_State::pGLContext;
MG_State::pGLContext = MakeShared<MG_State::GLState::GLContext>();
GLfloat clear[4] = {-1.0f, -1.0f, -1.0f, -1.0f};
MG_Impl::GLImpl::GetFloatv(GL_COLOR_CLEAR_VALUE, clear);
const GLenum error = MG_Impl::GLImpl::GetError();
MG_State::pGLContext = previous;
EXPECT_EQ(error, GL_NO_ERROR);
for (const GLfloat channel : clear) EXPECT_FLOAT_EQ(channel, 0.0f);
}
TEST_F(RenderStateTest, PatchDefaultLevelsStartAtTheGLDefault) {
GLfloat outer[4] = {-1.0f, -1.0f, -1.0f, -1.0f};
MG_Impl::GLImpl::GetFloatv(GL_PATCH_DEFAULT_OUTER_LEVEL, outer);