OpenGL – Build high performance graphics

Implementing volume rendering using single-pass GPU ray casting

In this recipe, we will implement volume rendering using single-pass GPU ray casting. There are two basic approaches for doing GPU ray casting: the multi-pass approach and the single-pass approach. Both of these approaches differ in how they estimate the ray marching direction vectors. The single-pass approach uses a single fragment shader. The steps described here can be understood easily from the following diagram:

First, the camera ray direction is calculated by subtracting the vertex positions from the camera position. This gives the ray marching direction. The initial ray position ...