The 3DMark DirectX Raytracing feature test is designed to make ray-tracing performance the limiting factor. Instead of relying on traditional rendering techniques, the whole scene is ray-traced and drawn in one pass.
Camera rays are traced across the field of view with small random offsets to simulate a depth of field effect. The frame rate is determined by the time taken to trace and shade a set number of samples for each pixel, combine the results with previous samples and present the output on the screen. The rendering resolution is 2560 × 1440.
DirectX Raytracing Tier 1.1
DirectX Raytracing helps developers create realistic reflections, shadows, and other effects that are difficult to achieve with other techniques.
DirectX Raytracing Tier 1.1 introduces new features and capabilities that improve efficiency and give developers more flexibility and control. While the details of these improvements are beyond the scope of this guide, you can read more about DXR Tier 1.1 on the Microsoft DirectX Developer Blog and in the DirectX Raytracing Functional Spec.
This test uses features from DirectX Raytracing Tier 1.1 to create a realistic ray-traced depth of field effect.
Rendering
There is a minimal amount of traditional rendering in this test. Instead of drawing a GBuffer or using a rasterizer at all, camera rays are traced in a compute shader with random offsets to simulate a depth of field effect.
To keep light computation to a minimum, image-based lighting is used in addition to a baked light map.
Sampling
Camera rays are randomized with per-pixel offsets. There are 12 samples for each pixel when running the test with default settings.
When the camera is stationary, samples are accumulated at a rate of 12 samples per pixel per frame. This improves the appearance of the depth of field effect from slightly grainy to smooth over the span of several frames.
When the camera moves, a light motion blur is applied to reduce the noise that is a natural result of this ray-tracing technique.
Implementation
The test measures the peak ray-traversal performance of the GPU. All other work, such as illumination and post-processing, is kept to a minimum.
The ray-tracing acceleration structure is built only once. As the scene is static and non-animated, there is no need to update the acceleration structure during the test.
The test casts primary rays only. The rays are approximately sorted by direction on the CPU during the test initialization, which is possible because the sampling pattern in screen space is known beforehand. Generating the optimal ray order during initialization allows more coherent ray traversal for out-of-focus areas without the run-time cost of sorting.