Turning on the lights

When it comes to lighting in shaders, there’s a lot of hands-on mathematics. No longer can we rely on nice, neat OpenGL function calls in our main code. Instead, we must calculate the color of a pixel and consider the lighting in the fragment shader.

In the previous section, when you completed the exercise and loaded the granny model with the texture, it was unlit. It displayed the colors as they appear in the PNG texture file. To include lighting effects, we must determine how the light will influence the original color of the pixel taken from the texture. Over the years, a gradual improvement has been made to lighting models, which is evident if you take a look at the quality of computer graphics from 20 years ago up until now.

In this section, we will examine some popular lighting models and apply the mathematics to our fragment shader to light up the model.

Ambient lighting

Ambient lighting is lighting in a scene that has no apparent source...