HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 268

L glLogicOp opcode GL_OR_REVERSE GL_OR_INVERTED Resulting Value s | !d !s | d opcode is a symbolic constant chosen from the list above. In the explanation of the logical operations, s represents the incoming color index and d represents the index in the frame buffer. Standard C-language operators are used. As these bitwise operators suggest, the logical operation is applied independently to each bit pair of the source and destination indices or colors. Notes Color index logical operations are always supported. RGBA logical operations are supported only if the GL version is 1.1 or greater. When more than one RGBA color or index buffer is enabled for drawing, logical operations are performed separately for each enabled buffer, using for the destination value the contents of that buffer (see glDrawBuffer). Errors • GL_INVALID_ENUM is generated if opcode is not an accepted value. • GL_INVALID_OPERATION is generated if glLogicOp is executed between the execution of glBegin and the corresponding execution of glEnd. Associated Gets glGet with argument GL_LOGIC_OP_MODE. glIsEnabled with argument GL_COLOR_LOGIC_OP or GL_INDEX_LOGIC_OP. See Also glAlphaFunc, glBlendFunc, glDrawBuffer, glEnable, glStencilOp 268 Chapter 10