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
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
glDisable using the symbolic constant
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
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
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
GL_INVALID_OPERATION is generated if glLogicOp is called between
a call to glBegin and the corresponding
call to glEnd.
glGet with argument
glIsEnabled with argument
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© 1995 Uwe Behrens. All rights reserved.