Add end2end test for changing MAX_LEVEL with compressed texture

src/libANGLE/renderer/vulkan/TextureVk.cpp

@@ -1216,6 +1216,9 @@ angle::Result TextureVk::copyAndStageImageSubresource(ContextVk *contextVk,
     uint32_t bufferImageHeight = updatedExtents.height;
     if (desc.format.info->compressed)
     {
+        // In the case of a compressed texture, bufferRowLength can never be smaller than the
+        // compressed format's compressed block width, and bufferImageHeight can never be smaller
+        // than the compressed block height.
         bufferRowLength   = std::max(bufferRowLength, desc.format.info->compressedBlockWidth);
         bufferImageHeight = std::max(bufferImageHeight, desc.format.info->compressedBlockHeight);
     }

src/tests/gl_tests/TextureTest.cpp

@@ -6145,6 +6145,70 @@ TEST_P(ETC1CompressedTextureTest, ETC1CompressedSubImage)
     ASSERT_GL_NO_ERROR();
 }
 
+// Fully-define a compressed texture and draw; then decrease MAX_LEVEL and draw; then increase
+// MAX_LEVEL and draw.  This used to cause Vulkan validation errors.
+TEST_P(ETC1CompressedTextureTest, ETC1ShrinkThenGrowMaxLevels)
+{
+    // ETC texture formats are not supported on Mac OpenGL. http://anglebug.com/3853
+    ANGLE_SKIP_TEST_IF(IsOSX() && IsDesktopOpenGL());
+
+    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3);
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_compressed_ETC1_RGB8_sub_texture"));
+
+    const GLuint width  = 4u;
+    const GLuint height = 4u;
+
+    setWindowWidth(width);
+    setWindowHeight(height);
+
+    // Setup primary Texture
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+
+    if (getClientMajorVersion() < 3)
+    {
+        glTexStorage2DEXT(GL_TEXTURE_2D, 3, GL_ETC1_RGB8_OES, width, height);
+    }
+    else
+    {
+        glTexStorage2D(GL_TEXTURE_2D, 3, GL_ETC1_RGB8_OES, width, height);
+    }
+    ASSERT_GL_NO_ERROR();
+
+    // Populate a subimage of the texture
+    glCompressedTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_ETC1_RGB8_OES,
+                              width * height / 2u, kCompressedImageETC2);
+    glCompressedTexSubImage2D(GL_TEXTURE_2D, 1, 0, 0, width / 2, height / 2, GL_ETC1_RGB8_OES,
+                              width * height / 2u, kCompressedImageETC2);
+    glCompressedTexSubImage2D(GL_TEXTURE_2D, 2, 0, 0, width / 4, height / 4, GL_ETC1_RGB8_OES,
+                              width * height / 2u, kCompressedImageETC2);
+    ASSERT_GL_NO_ERROR();
+
+    // Set MAX_LEVEL to 2 (the highest level)
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 2);
+
+    // Render and ensure we get red
+    glUseProgram(mProgram);
+    drawQuad(mProgram, "position", 0.5f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);
+    ASSERT_GL_NO_ERROR();
+
+    // Decrease MAX_LEVEL to 0, render, and ensure we still get red
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
+    drawQuad(mProgram, "position", 0.5f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);
+    ASSERT_GL_NO_ERROR();
+
+    // Increase MAX_LEVEL back to 2, render, and ensure we still get red
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 2);
+    drawQuad(mProgram, "position", 0.5f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);
+    ASSERT_GL_NO_ERROR();
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these
 // tests should be run against.
 ANGLE_INSTANTIATE_TEST_ES2(Texture2DTest);