# NVIDIA Vulkan Trace Rays Indirect Tutorial This is an extension of the [Vulkan ray tracing tutorial](https://nvpro-samples.github.io/vk_raytracing_tutorial_KHR/vkrt_tutorial.md.html). We will discuss the `vkCmdTraceRaysIndirectKHR` command, which allows the `width`, `height`, and `depth` of a trace ray command to be specifed by a buffer on the device, rather than directly by the host. As a demonstration, this example will add colorful lanterns to the scene that add their own light and shadows, with a finite radius of effect. A compute shader will calculate scissor rectangles for each lantern, and an indirect trace rays command will dispatch rays for lanterns only within those scissor rectangles. [