How can you optimize shader code for VR and AR apps?

2 Simplify your calculations

Shaders often perform complex calculations to create realistic lighting, shadows, reflections, and other effects. However, these calculations can be costly in terms of performance and battery life. To optimize your shaders, you should simplify your calculations as much as possible without sacrificing the visual quality. This can be done by using lower precision data types like half or fixed instead of float, precomputed values like lookup tables, constants, or uniforms instead of calculating them on the fly, approximations like dot products, lerp, or smoothstep instead of trigonometric functions, pow, or exp, and by using branching sparingly and avoiding loops and conditionals that depend on dynamic variables. Additionally, texture compression and mipmapping can also reduce the memory footprint and bandwidth of your textures.

3 Reduce your draw calls

Draw calls are expensive, as they require the CPU to communicate with the GPU and the GPU to switch between different shaders and states. To optimize your shaders, you should reduce the number of draw calls as much as possible without compromising visual quality. Instancing can be used to render multiple copies of the same mesh with a single draw call, while batching combines multiple meshes that use the same shader and state into one draw call. Atlasing packs multiple textures into a single texture, and UV coordinates can be used to access them. Shader variants create different versions of the same shader with different features or parameters, which can be switched between at runtime using keywords.

4 Test and profile your shaders

The best way to optimize your shaders is to test and profile them on your target platforms, and measure their impact on performance and battery life. You can use tools such as RenderDoc, GPUView, or Xcode to capture and analyze your GPU workload, and identify the bottlenecks and inefficiencies in your shader code. You can also use tools such as Unity's Shader Graph or Unreal Engine's Material Editor to create and edit your shaders visually, and see the changes in real time. By testing and profiling your shaders, you can find the optimal balance between quality and performance for your VR and AR apps.

5 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?