czm_projection

An automatic GLSL uniform representing a 4x4 projection transformation matrix that transforms eye coordinates to clip coordinates. Clip coordinates is the coordinate system for a vertex shader's gl_Position output.

Like all automatic uniforms, czm_projection 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.

// GLSL declaration
uniform mat4 czm_projection;

// Example
gl_Position = czm_projection * eyePosition;