czm_viewportOrthographic
An automatic GLSL uniform representing a 4x4 orthographic projection matrix that
transforms window coordinates to clip coordinates. Clip coordinates is the
coordinate system for a vertex shader's gl_Position output.
This transform is useful when a vertex shader inputs or manipulates window coordinates
as done by BillboardCollection.
Do not confuse czm_viewportTransformation with czm_viewportOrthographic.
The former transforms from normalized device coordinates to window coordinates; the later transforms
from window coordinates to clip coordinates, and is often used to assign to gl_Position.
Like all automatic uniforms, czm_viewportOrthographic 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 mat4 czm_viewportOrthographic; // Example gl_Position = czm_viewportOrthographic * vec4(windowPosition, 0.0, 1.0);