What are the best practices for optimizing a game engine for virtual reality?

1 Reduce draw calls

A draw call is a command that tells the GPU to render a batch of objects with the same material and shader. The more draw calls, the more CPU overhead and GPU workload. Therefore, reducing draw calls is essential for improving VR performance, as VR requires rendering two views for each eye at a high resolution and refresh rate. Some ways to reduce draw calls are using static and dynamic batching, using instancing, using texture atlases, and using mesh simplification.

2 Use occlusion culling

Occlusion culling is a technique that prevents the rendering of objects that are not visible to the camera, such as those behind walls or other occluders. This can save a lot of GPU resources and improve frame rates, especially in complex scenes with many objects. Occlusion culling can be done manually or automatically by the game engine, depending on the level of control and accuracy needed. Some game engines also support occlusion areas, which are predefined volumes that indicate which objects are visible from within them.

3 Implement dynamic resolution

Dynamic resolution is a technique that adjusts the resolution of the render target based on the performance and quality requirements. For example, if the frame rate drops below a certain threshold, the resolution can be lowered to maintain a smooth experience. Conversely, if the performance is good, the resolution can be increased to enhance the image quality. Dynamic resolution can be applied to the whole scene or to specific elements, such as shadows, reflections, or post-processing effects.

4 Apply VR-specific rendering techniques

VR has some unique characteristics that require special rendering techniques to optimize the quality and performance of the game engine. For example, VR uses stereoscopic rendering, which means that each eye has a slightly different perspective and projection. This can cause issues such as distortion, aliasing, and chromatic aberration, which can be mitigated by using techniques such as lens-matched shading, multisample anti-aliasing, and chromatic aberration correction. Another example is VR uses head tracking, which means that the camera position and orientation change constantly. This can cause issues such as latency, jitter, and motion blur, which can be reduced by using techniques such as asynchronous timewarp, reprojection, and motion vector smoothing.

5 Test and profile your game engine

The final and most important step for optimizing a game engine for VR is to test and profile your game engine on different VR devices and platforms. Testing and profiling can help you identify and fix performance bottlenecks, bugs, and compatibility issues. You can use various tools and metrics to measure and analyze your game engine's performance, such as frame rate, frame time, CPU and GPU usage, memory allocation, draw calls, and VR-specific parameters such as resolution, refresh rate, and latency. You can also use different settings and scenarios to test and optimize your game engine for different levels of quality and performance.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?