Index for Section 3G

Alphabetical listing for G

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glLogicOp(3G)
NAME
  glLogicOp - specify a logical pixel operation for color index rendering

SYNOPSIS
  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(3), glBlendFunc(3), glDrawBuffer(3), glEnable(3),
  glStencilOp(3)

Index for Section 3G

Alphabetical listing for G

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