glLogicOp
NAME
glLogicOp -- specify a logical pixel operation for rendering
C SPECIFICATION
void glLogicOp(GLenum opcode)
PARAMETERS
- 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.
DESCRIPTION
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.
NOTES
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.
ERRORS
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.
ASSOCIATED GETS
glGet with argument
GL_LOGIC_OP_MODE
glIsEnabled with argument
GL_LOGIC_OP
SEE ALSO
glAlphaFunc,
glBlendFunc,
glDrawBuffer,
glEnable,
glStencilOp
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© 1995 Uwe Behrens. All rights reserved.