Use this override mode to visualize the overall complexity of your scene, highlighting potential areas to investigate for optimization. If a scene renders only a few objects, the amount of overdraw is usually low and no further optimization is required. If a scene has many overlapping objects, or objects with semitransparent textures (such as smoke, fog, or water), this typically results in a high load on the graphics card and therefore lower frame rates.
The Overdraw Visualization mode fills the frame buffer with a brightness value according to the numbers of times each pixel is drawn. The brightness of a pixel indicates the number of times each pixel was “touched” by a draw call or clear call. The darker a pixel, the fewer number of times it has been overdrawn; conversely, the lighter a pixel, the more times it was overdrawn. Bright areas of the screen may provide optimization opportunities such as culling primitives prior to rendering them, altering the draw order (so that z-buffer tests will reject many primitives prior to rendering them with an expensive pixel shader), or using other level-of-detail optimizations that simplify the complexity of the scene.
If the overdraw value in one or more areas of the scene is high, use the Intel® GPA Frame Analyzer with the Pixel History feature with overdraw mode enabled – these will help you understand which ergs are being rendered into each pixel and help pinpoint optimization opportunities.
The current implementation may not take into account overdraw in off-screen render target surfaces, if such surfaces are used as a texture with a non-full screen quad draw call. However, if an off-screen render target is used as a full screen quad, all accumulated overdrawn pixels will be visualized.
Normal Picture Overdraw Visualization
Override Modes Overview
Disable all overrides
Disable Draw Calls
Simple Pixel Shader
1×1 Scissor Rect
Disable Texture Filtering
Disable Alpha Blending
Disable Alpha Test