Demo of approximate real-time indirect lighting with Reflective Shadows Maps using regl.
This is an implementation of Indirect Lighting using Reflective Shadow Maps. This technique results in some nice color bleeding effects, which can be seen in the red glow on Lucy(statue) and the blue glow on the cute rabbit. This is light that has bounced from the colored walls.
We render the scene from the perspective of the light source, and for every pixel we store the normal, world-space position and flux in a buffer, the RSM. When shading a fragment, we will now gather the illumination from the adjacent pixels in the RSM, and sum their contributions. We can by doing this approximate a lambertian diffuse indirect lighting component, and this results in some nice color bleeding effects.
The issue with the approach is that lots of samples must be taken for decent results. Our implementation uses 64 samples, which is a lot, considering all these samples must be taken for every single fragment on the screen. In order to avoid doing this calculation for invisible surfaces, we adopt a deferred shading approach. However, it is still quite expensive.
In the original paper a screen-space interpolation approach is described, that can greatly decrease the number of times we must perform the indirect lighting calculation. In order to keep this demo simple, and because of laziness, we did not implement this, however. Note that this is a possible future improvement to the implemention, though.,
First install all dependencies by doing
npm installTo then run the demo, do
npm run start