OpenGL 4 Shading Language Cookbook - Third Edition

How to do it...

To modify the Phong reflection model to use flat shading, take the following steps:

1. Use the same vertex shader as in the Phong example provided earlier. Change the output variable LightIntensity as follows:

flat out vec3 LightIntensity; 

2. Change the corresponding variable in the fragment shader to use the flat qualifier:

flat in vec3 LightIntensity; 

3. Compile and link both shaders within the OpenGL application, and install the shader program prior to rendering.