The vertex shader computes the shading equation in eye coordinates. It begins by transforming the vertex normal into camera coordinates and normalizing, then storing the result in n. The vertex position is also transformed into camera coordinates and stored in camCoords.
The ambient component is computed and stored in the variable ambient.
Next, we compute the normalized direction towards the light source (s). This is done by subtracting the vertex position in camera coordinates from the light position and normalizing the result.
The dot product of s and n is computed next. As in the preceding recipe, we use the built-in function max to limit the range of values to between zero and one. The result is stored in the variable ...
