OpenGL 4 Shading Language Cookbook - Third Edition

How it works...

The vertex shader has two output variables: Position and Normal. In the main function, we convert the vertex normal to camera coordinates by transforming with the normal matrix, and then store the converted value in Normal. Similarly, the vertex position is converted to eye coordinates by transforming it by the model-view matrix, and the converted value is stored in Position. The values of Position and Normal are automatically interpolated and provided to the fragment shader via the corresponding input variables. The fragment shader then computes the Phong reflection model using the values provided. Here, we re-normalize the Normal vector because the interpolation process can create vectors that are not of unit length.