UL Benchmarks has announced that it will be adding a new Variable-Rate Shading benchmark test to 3DMark on August 26th. 3DMark feature tests are special tests designed to highlight specific techniques, functions or capabilities, and its VRS feature test is designed to help you compare differences in performance and image quality when using variable-rate shading.
In case you weren’t aware of, Variable-Rate Shading (VRS) is a new feature in DirectX 12 that allows developers to improve performance by selectively reducing the level of detail in parts of the frame where there will be little noticeable effect on image quality. Shading rate refers to the number of pixel shader operations called for each pixel. Higher shading rates improve accuracy but are more demanding for the GPU whereas lower shading rates improve performance at the cost of visual fidelity.
With Variable-Rate Shading, developers can vary the shading rate within a single frame. By using VRS to lower the shading rate for parts of the frame that are in deep shadow, far from the camera, or peripheral to the player’s focus, for example, a game can run at a higher frame rate with little perceptible loss in visual quality.
As UL Benchmarks noted, with VRS, a single pixel shader operation can be applied to a block of pixels, for example shading a 4×4 block of pixels with one operation rather than 16 separate operations.
In the 3DMark VRS feature test, the shading rate varies with camera distance when VRS is enabled: 4×4 for the furthest objects, (the blue areas in the image below), 2×2 for the middle-distance geometry (green areas), and 1×1 (red areas) for the closest foreground objects.