Implementing per-fragment spot light
We will now implement per-fragment spot light. Spot light is a special point light that emits light in a directional cone. The size of this cone is determined by the spot cutoff amount, which is given in angles, as shown in the following figure. In addition, the sharpness of the spot is controlled by the parameter spot exponent. A higher value of the exponent gives a sharper falloff and vice versa.
Getting started
The code for this recipe is contained in the Chapter4/SpotLight directory. The vertex shader is the same as in the point light recipe. The fragment shader calculates the diffuse component, as in the Implementing per-vertex and per-fragment point lighting recipe.
How to do it…
Let us start this recipe by following these simple steps:
From the light's object space position and spot light target's position, calculate the spot light direction vector in eye space.
spotDirectionES = glm::normalize(glm::vec3(MV*glm::vec4(spotPositionOS-lightPosOS,0)))
In...
