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[Fix, Test] (MG_Backend/DirectVulkan): a multisample resolve that must also change orientation resolves through a pooled scratch image, then blits

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swung0x48
2026-08-11 10:49:58 -04:00
parent dbae4eda10
commit 757b31592d
3 changed files with 225 additions and 13 deletions
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MobileGL/MG_IntegrationTest/Scenarios/ClearThenReadPixelsScenario.cpp
+69
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@@ -233,6 +233,75 @@ void main() { o_color = vec4(0.1, 0.2, 0.3, 1.0); }
glDeleteProgram(program);
}
// A MULTISAMPLE-RESOLVE blit into the default framebuffer has to change orientation like any
// other, but vkCmdResolveImage takes one offset per side and cannot invert an axis, so it used
// to land the mirrored band. The renderer now resolves into a single-sample scratch image and
// blits from there. The source is painted in two horizontal bands so the mirror is visible;
// a full-extent uniform blit is a fixed point of the flip and would prove nothing.
TEST_F(ClearThenReadPixelsScenario, AMultisampleResolveBlitIntoTheDefaultFramebufferKeepsItsOrientation) {
if (!Ready()) return;
HeadlessGL& gl = Gl();
const int width = gl.Width();
const int height = gl.Height();
ASSERT_GE(height, 8);
GLint maxSamples = 0;
glGetIntegerv(GL_MAX_SAMPLES, &maxSamples);
if (maxSamples < 2) {
GTEST_SKIP() << "GL_MAX_SAMPLES is " << maxSamples << "; this needs a multisample renderbuffer";
}
GLuint fbo = 0, rbo = 0;
glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 2, GL_RGBA8, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, rbo);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
glDeleteRenderbuffers(1, &rbo);
glDeleteFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
GTEST_SKIP() << "no complete 2x multisample RGBA8 renderbuffer on this driver";
}
glViewport(0, 0, width, height);
// Bottom half red, top half blue - via scissored clears, so no shader is involved.
glEnable(GL_SCISSOR_TEST);
glScissor(0, 0, width, height / 2);
ClearTo(1.0f, 0.0f, 0.0f, 1.0f);
glScissor(0, height / 2, width, height - height / 2);
ClearTo(0.0f, 0.0f, 1.0f, 1.0f);
glDisable(GL_SCISSOR_TEST);
BindDefaultFramebuffer();
glViewport(0, 0, width, height);
ClearTo(0.0f, 0.0f, 0.0f, 1.0f);
glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
EXPECT_EQ(FirstGLError(), 0u);
const Image resolved = ReadPixels(width, height);
EXPECT_EQ(FirstGLError(), 0u);
const Rgba8 bottom = resolved.At(width / 2, height / 4);
const Rgba8 top = resolved.At(width / 2, height - 1 - height / 4);
EXPECT_GT(bottom.r, 200) << "the bottom band should be red after the resolve, got rgba("
<< static_cast<int>(bottom.r) << ", " << static_cast<int>(bottom.g) << ", "
<< static_cast<int>(bottom.b) << ") - blue there means the resolve landed "
<< "in the mirrored band";
EXPECT_LT(bottom.b, 60);
EXPECT_GT(top.b, 200) << "the top band should be blue after the resolve, got rgba("
<< static_cast<int>(top.r) << ", " << static_cast<int>(top.g) << ", "
<< static_cast<int>(top.b) << ")";
EXPECT_LT(top.r, 60);
glDeleteRenderbuffers(1, &rbo);
glDeleteFramebuffers(1, &fbo);
gl.EndFrame();
}
// The same ordering claim for the path that DOES open a render pass. It passes today (the
// render pass folds the clear into its loadOp and pops it), and it is here so a future change
// to the pending-clear lifecycle cannot quietly reverse clear and draw.