HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 481

V glVisibilityBufferhp Visibility Tests can be used by a programmer to determine whether or not a primitive or set of primitives are visible against the current contents of the depth buffer; "Visibile" in this context means that at least one pixel passes the depth test. This differs from previous Occlusion Culling extensions by allowing the programmer to provide memory for many different Visibility Test results to be returned at the same time. Notes The contents of 'buffer' are undefined before a glGet of GL_VISIBILITY_TEST_hp is called. See Description section above for more information on when the contents of 'buffer' become valid. The programmer is responsible for allocating the memory for 'buffer'. If an incorrect 'size' is specified, memory corruption may occur. Errors • GL_INVALID_VALUE is generated if 'size' is negative. • GL_INVALID_OPERATION is generated if glVisibilityBufferhp is called while GL_VISIBILITY_TEST_hp is enabled (via glEnable()), or if glEnable(GL_VISIBILITY_TEST_hp) is called before glVisibilityBufferhp is called at least once. • GL_INVALID_OPERATION is generated if glVisibilityBufferhp is called between a call to glBegin and the corresponding call to glEnd. Associated Gets glGet with argument GL_VISIBILITY_TEST_hp See Also glNextVisibilityTesthp glIsEnabled with argument Chapter 20 481