glLogicOp -- specify a logical pixel operation for rendering


void glLogicOp(GLenum opcode)


Specifies a symbolic constant that selects a logical operation. The following symbols are accepted: GL_CLEAR, GL_SET, GL_COPY, GL_COPY_INVERTED, GL_NOOP, GL_INVERT, GL_AND, GL_NAND, GL_OR, GL_NOR, GL_XOR, GL_EQUIV, GL_AND_REVERSE, GL_AND_INVERTED, GL_OR_REVERSE, and GL_OR_INVERTED.


glLogicOp specifies a logical operation that, when enabled, combines the incoming color index and the color index at the corresponding location in the frame buffer. The logical operation is enabled or disabled with glEnable and glDisable using the symbolic constant GL_LOGIC_OP.

opcode is a symbolic constant chosen from the list below. 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.

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Logical pixel operations are not applied to RGBA color buffers.

When more than one color index buffer is enabled for drawing, logical operations are done separately for each enabled buffer, using for the destination index the contents of that buffer (see glDrawBuffer).

opcode mst be one of the sixteen accepted values. Other values result in an error.


GL_INVALID_ENUM is generated if opcode is not an accepted value.

GL_INVALID_OPERATION is generated if glLogicOp is called between a call to glBegin and the corresponding call to glEnd.


glGet with argument GL_LOGIC_OP_MODE
glIsEnabled with argument GL_LOGIC_OP


glAlphaFunc, glBlendFunc, glDrawBuffer, glEnable, glStencilOp

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© 1995 Uwe Behrens. All rights reserved.