gllogicop(3g) [xfree86 man page]

GLLOGICOP(3G)															     GLLOGICOP(3G)

NAME

       glLogicOp - specify a logical pixel operation for color index 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. The initial value is GL_COPY.

DESCRIPTION

       glLogicOp  specifies  a logical operation that, when enabled, is applied between the incoming color index or RGBA color and the color index
       or 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 for RGBA mode or GL_INDEX_LOGIC_OP for color index mode. The initial value is disabled for
       both operations.

							 ---------------------------------------
							 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
       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 or colors.

NOTES

       Color index logical operations are always supported. RGBA logical operations are supported only if the GL version is 1.1 or greater.

       When more than one RGBA color or index 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).

ERRORS

       GL_INVALID_ENUM is generated if opcode is not an accepted value.

       GL_INVALID_OPERATION is generated if glLogicOp is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS

       glGet with argument GL_LOGIC_OP_MODE.
       glIsEnabled with argument GL_COLOR_LOGIC_OP or GL_INDEX_LOGIC_OP.

SEE ALSO

       glAlphaFunc(3G), glBlendFunc(3G), glDrawBuffer(3G), glEnable(3G), glStencilOp(3G)

																     GLLOGICOP(3G)

GLLOGICOP(3G)							   OpenGL Manual						     GLLOGICOP(3G)

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. The initial value is GL_COPY.

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.

SEE ALSO

       glBlendFunc(), glDrawBuffer(), glEnable(), glStencilOp()

COPYRIGHT

       Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

AUTHORS

       opengl.org

opengl.org							    06/10/2014							     GLLOGICOP(3G)