2003-2004
Silicon Graphics, Inc.
glLogicOp
3G
glLogicOp
specify a logical pixel operation
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. The initial value is
GL_COPY.
Description
glLogicOp
specifies a logical operation that, when enabled, is applied
between the incoming color and the color at the corresponding
location in the frame buffer.
To enable or disable the logical operation, call
glEnable and
glDisable
with argument GL_COLOR_LOGIC_OP.
Logical operation is initially disabled.
Opcode
Resulting Operation
GL_CLEAR
0
GL_SET
1
GL_COPY
s
GL_COPY_INVERTED
~s
GL_NOOP
d
GL_INVERT
~d
GL_AND
s&d
GL_NAND
~s&d
GL_OR
s|d
GL_NOR
~s|d
GL_XOR
s^d
GL_EQUIV
~s^d
GL_AND_REVERSE
s&~d
GL_AND_INVERTED
~s&d
GL_OR_REVERSE
s|~d
GL_OR_INVERTED
~s|d
opcode
is a symbolic constant chosen from the list above. In the
explanation of the logical operations, s
represents the incoming color and d
represents the color 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.
Errors
GL_INVALID_ENUM is generated if
opcode is not an accepted value.
See Also
glAlphaFunc,
glBlendFunc,
glEnable,
glStencilOp
Copyright
Copyright 2003-2004
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt.