UL Benchmarks has announced that it has added a Tier 2 Variable-Rate Shading benchmark test in 3DMark. In case you aren’t aware of, Variable-Rate Shading (VRS) is a new DirectX 12 feature that lets game developers improve performance by selectively reducing the level of detail in parts of the frame where it’s unlikely to be noticed.
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. Lower shading rates improve performance at the cost of visual fidelity.
With Variable-Rate Shading, 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.
By applying the technique carefully, VRS can deliver a big performance boost with little impact on visual quality. With VRS, games can run at higher frame rates, in a higher resolution, or with higher quality settings.
There are two tiers of VRS support in DirectX. With Tier 1, developers can specify a different shading rate for each draw call. Tier 2 adds more flexibility and control by allowing different shading rates within each draw call.
In 3DMark’s new Tier 2 test, lower shading rates are used in areas where there is less contrast between neighboring pixels, for example, areas in shadow or with fewer details.
The 3DMark VRS feature test runs in two passes. VRS is disabled on the first pass of the test to provide a baseline for comparison. Variable-Rate Shading is enabled for the second pass. The test then reports the average frame rate for each pass and calculates the performance gained with VRS.
The VRS feature test is available as a free update for 3DMark Advanced Edition and for 3DMark Professional Edition customers with a valid annual license.