HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 103

Chapter 4 D glDepthRange glDepthRange glDepthRange: specify mapping of depth values from normalized device coordinates to window coordinates. C Specification void glDepthRange( GLclampd zNear, GLclampd zFar) Parameters zNear zFar Specifies the mapping of the near clipping plane to window coordinates. The initial value is 0. Specifies the mapping of the far clipping plane to window coordinates. The initial value is 1. Description After clipping and division by w, depth coordinates range from - 1 to 1, corresponding to the near and far clipping planes. glDepthRange specifies a linear mapping of the normalized depth coordinates in this range to window depth coordinates. Regardless of the actual depth buffer implementation, window coordinate depth values are treated as though they range from 0 through 1 (like color components). Thus, the values accepted by glDepthRange are both clamped to this range before they are accepted. The setting of (0, 1) maps the near plane to 0 and the far plane to 1. With this mapping, the depth buffer range is fully utilized. Notes It is not necessary that zNear be less than zFar. Reverse mappings such as zNear = 1, and zFar = 0 are acceptable. Errors • GL_INVALID_OPERATION is generated if glDepthRange is executed between the execution of glBegin and the corresponding execution of glEnd. Associated Gets glGet with argument GL_DEPTH_RANGE See Also glDepthFunc, glPolygonOffset, glViewport 103