Signature
Parameters
Description
glLogicOp
specifies a logical operation that,
when enabled,
is applied between the incoming RGBA color
and the RGBA color at the corresponding location in the
frame buffer.
To enable or disable the logical operation, call
glEnable
and
glDisable
using the symbolic constant
GL_COLOR_LOGIC_OP
. The initial value is
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 colors.
Notes
When more than one RGBA color 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
).
Logic operations have no effect on floating point draw buffers. However, if
GL_COLOR_LOGIC_OP
is enabled, blending is still disabled
in this case.
Errors
GL_INVALID_ENUM
is generated if
opcode
is not an accepted value.
Associated Gets
glGet
with argument
GL_LOGIC_OP_MODE
.
glIsEnabled
with argument
GL_COLOR_LOGIC_OP
.
Version Support
| glLogicOp |
See Also
Copyright
Copyright
1991-2006 Silicon Graphics, Inc.
Copyright
2010-2014 Khronos Group.
This document is licensed under the SGI Free Software B License.
For details, see
http://oss.sgi.com/projects/FreeB/
.