chromium/third_party/dawn/src/dawn/tests/end2end/MultisampledSamplingTests.cpp

// Copyright 2020 The Dawn & Tint Authors
//
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#include <vector>

#include "dawn/common/Math.h"
#include "dawn/tests/DawnTest.h"
#include "dawn/utils/ComboRenderPipelineDescriptor.h"
#include "dawn/utils/WGPUHelpers.h"

namespace dawn {
namespace {

// https://github.com/gpuweb/gpuweb/issues/108
// Vulkan, Metal, and D3D11 have the same standard multisample pattern. D3D12 is the same as
// D3D11 but it was left out of the documentation.
// {0.375, 0.125}, {0.875, 0.375}, {0.125 0.625}, {0.625, 0.875}
// In this test, we store them in -1 to 1 space because it makes it
// simpler to upload vertex data. Y is flipped because there is a flip between clip space and
// rasterization space.
static constexpr std::array<std::array<float, 2>, 4> kSamplePositions = …;

class MultisampledSamplingTest : public DawnTest { … };

// Test that the multisampling sample positions are correct. This test works by drawing a
// thin quad multiple times from left to right and from top to bottom on a 1x1 canvas.
// Each time, the quad should cover a single sample position.
// After drawing, a compute shader fetches all of the samples (both color and depth),
// and we check that only the one covered has data.
// We "scan" the vertical and horizontal dimensions separately to check that the triangle
// must cover both the X and Y coordinates of the sample position (no false positives if
// it covers the X position but not the Y, or vice versa).
TEST_P(MultisampledSamplingTest, SamplePositions) { … }

DAWN_INSTANTIATE_TEST(MultisampledSamplingTest,
                      D3D11Backend(),
                      D3D12Backend(),
                      MetalBackend(),
                      OpenGLBackend(),
                      OpenGLESBackend(),
                      VulkanBackend());

}  // anonymous namespace
}  // namespace dawn