Helliaca / RRad

RRad

An implementation of progressive radiosity that runs on the GPU.

It serves as a demonstration for how visibility-determination is the only major hurdle that prevents radiosity from easily running on the GPU. The implementation is simple and utilizes discrete ray-intersections inside the fragment shader to determine visibility.

Overview

The program generates a set of textures that contain input data. Namely: normal vector, position and area-fraction. The emissive color is stored into two textures ligTex0 and ligTex1. With each pass, the output lighting is written to one of these textures, with the other serving as the input.

The radiosity pass is performed by the make_lightmap shader. This shader includes a occluded(A, B) function that determines if two locations are mutually visible. Visibility is determined through explicit intersection functions (ray_cone, ray_cube and ray_sphere) which are executed for 'virtual' shapes that are hard-coded into the shader. You can view and modify these inside the occluded function.

Dependencies

• Assimp 3.1.1
• GLFW 3.2.1
• GLM 9.8.5
• An OpenGL 4.5 loader generated with glad 0.1.16a0

Manual

Once you start the program, you can use the separate commandline to control execution. Available commands:

• pass to run a radiosity pass - ie. simulate a bounce of light.
• phong to show direct lighting via a standard phong shader.
• res or showres to show the texture resolution as a black-and-white checkers pattern.
• tex to show the texture in its UV-coordinates.
• obj to show the texture mapped onto the underlying 3D model.
• mode to toggle between the two former modes.
• tex [texturename] to display a given input-texture. Avalilable parameters: posTex, nrmTex, arfTex, ligTex1.