Vulkan: Fix deferred clears vs 3D textures

src/libANGLE/renderer/vulkan/FramebufferVk.cpp

@@ -303,8 +303,10 @@ bool IsAnyAttachment3DWithoutAllLayers(const RenderTargetCache<RenderTargetVk> &
     {
         RenderTargetVk *colorRenderTarget = colorRenderTargets[colorIndexGL];
         ASSERT(colorRenderTarget);
-        if (colorRenderTarget->getLayerCount() > framebufferLayerCount &&
-            colorRenderTarget->getImageForRenderPass().getType() == VK_IMAGE_TYPE_3D)
+
+        const vk::ImageHelper &image = colorRenderTarget->getImageForRenderPass();
+
+        if (image.getType() == VK_IMAGE_TYPE_3D && image.getExtents().depth > framebufferLayerCount)
         {
             return true;
         }

src/libANGLE/renderer/vulkan/RenderTargetVk.cpp

@@ -294,11 +294,15 @@ angle::Result RenderTargetVk::flushStagedUpdates(ContextVk *contextVk,
     ASSERT(mImage->valid() && (!isResolveImageOwnerOfData() || mResolveImage->valid()));
     ASSERT(framebufferLayerCount != 0);
 
-    // Note that the layer index for 3D textures is always zero according to Vulkan.
+    // It's impossible to defer clears to slices of a 3D images, as the clear applies to all the
+    // slices, while deferred clears only clear a single slice (where the framebuffer is attached).
+    // Additionally, the layer index for 3D textures is always zero according to Vulkan.
     uint32_t layerIndex = mLayerIndex;
     if (mImage->getType() == VK_IMAGE_TYPE_3D)
     {
-        layerIndex = 0;
+        layerIndex         = 0;
+        deferredClears     = nullptr;
+        deferredClearIndex = 0;
     }
 
     vk::ImageHelper *image = getOwnerOfData();

src/tests/gl_tests/ClearTest.cpp

@@ -2482,6 +2482,39 @@ TEST_P(ClearTest, DISABLED_ClearReachesWindow)
     angle::Sleep(2000);
 }
 
+// Test that clearing slices of a 3D texture and reading them back works.
+TEST_P(ClearTestES3, ClearAndReadPixels3DTexture)
+{
+    constexpr uint32_t kWidth  = 128;
+    constexpr uint32_t kHeight = 128;
+    constexpr uint32_t kDepth  = 7;
+
+    GLTexture texture;
+    glBindTexture(GL_TEXTURE_3D, texture);
+    glTexStorage3D(GL_TEXTURE_3D, 1, GL_RGBA8, kWidth, kHeight, kDepth);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAX_LEVEL, 0);
+
+    std::array<GLColor, kDepth> clearColors = {
+        GLColor::red,  GLColor::green,   GLColor::blue,  GLColor::yellow,
+        GLColor::cyan, GLColor::magenta, GLColor::white,
+    };
+
+    GLFramebuffer framebuffer;
+    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
+
+    for (uint32_t z = 0; z < kDepth; ++z)
+    {
+        glFramebufferTextureLayer(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture, 0, z);
+        glClearBufferfv(GL_COLOR, 0, clearColors[z].toNormalizedVector().data());
+    }
+
+    for (uint32_t z = 0; z < kDepth; ++z)
+    {
+        glFramebufferTextureLayer(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture, 0, z);
+        EXPECT_PIXEL_COLOR_EQ(0, 0, clearColors[z]);
+    }
+}
+
 #ifdef Bool
 // X11 craziness.
 #    undef Bool