czm_sunDirectionWC
An automatic GLSL uniform representing the normalized direction to the sun in world coordinates.
This is commonly used for directional lighting computations.
Like all automatic uniforms, czm_sunDirectionWC does not need to be explicitly declared.
However, it can be explicitly declared when a shader is also used by other applications such
as a third-party authoring tool.
Example
// GLSL declaration uniform vec3 czm_sunDirectionWC;