glClear              (3x)  - clear buffers to preset values
glClearAccum         (3x)  - specify clear values for the accumulation buffer
glClearColor         (3x)  - specify clear values for the color buffers
glClearDepth         (3x)  - specify the clear value for the depth buffer
glClearIndex         (3x)  - specify the clear value for the color index buffers
glClearStencil       (3x)  - specify the clear value for the stencil buffer