Based on the recently updated deferred shading example, I have added a new example to my open source C++ Vulkan samples. This example adds dynamic shadows from multiple light sources, showcasing a few technologies that can be used to make rendering of multiple shadows more efficient.
To achieve this, the example uses a layered depth attachment with one layer per light source that is sampled in the final scene composition. Traditionally one would do multiple passes to render the depth maps for the scene’s light source, and to avoid this the example also uses shader instancing by doing multiple invocations in the geometry shader. The geometry shader then uses the invocation index to output into the different layers of the depth attachment, with the matrices from the different point-of-views of the light sources getting passed as an array.
This is an approach that fits modern GPUs very well and allows for an arbitrary number of shadow casting light sources to be added without the need to add multiple render passes.