glBitmap

GLBITMAP(3G)							 GLBITMAP(3G)



NAME
       glBitmap - draw a bitmap


C SPECIFICATION
       void glBitmap( GLsizei width,
		      GLsizei height,
		      GLfloat xorig,
		      GLfloat yorig,
		      GLfloat xmove,
		      GLfloat ymove,
		      const GLubyte *bitmap )


PARAMETERS
       width, height Specify  the pixel width and height of the bitmap image.

       xorig, yorig  Specify the location of the origin in the bitmap  image.
		     The origin is measured from the lower left corner of the
		     bitmap, with right and up being the positive axes.

       xmove, ymove  Specify the x and y offsets to be added to	 the  current
		     raster position after the bitmap is drawn.

       bitmap	     Specifies the address of the bitmap image.

DESCRIPTION
       A bitmap is a binary image.  When drawn, the bitmap is positioned rel-
       ative to the current raster position, and frame buffer  pixels  corre-
       sponding	 to  1’s  in  the bitmap are written using the current raster
       color or index.	Frame buffer  pixels  corresponding  to	 0’s  in  the
       bitmap are not modified.

       glBitmap	 takes	seven  arguments.  The first pair specifies the width
       and height of the bitmap image.	The second pair specifies  the	loca-
       tion  of	 the  bitmap  origin relative to the lower left corner of the
       bitmap image.  The third pair of arguments specifies x and  y  offsets
       to  be  added to the current raster position after the bitmap has been
       drawn.  The final argument is a pointer to the bitmap image itself.

       The bitmap image is interpreted like image data for  the	 glDrawPixels
       command,	 with  width and height corresponding to the width and height
       arguments of that command, and with type set to GL_BITMAP  and  format
       set  to GL_COLOR_INDEX.	Modes specified using glPixelStore affect the
       interpretation  of  bitmap   image   data;   modes   specified	using
       glPixelTransfer do not.

       If  the current raster position is invalid, glBitmap is ignored.	 Oth-
       erwise, the lower left corner of the bitmap image is positioned at the
       window coordinates

				     xw=⌊xr−xo⌋

				     yw=⌊yr−yo⌋

       where (xr,yr) is the raster position and (xo,yo) is the bitmap origin.
       Fragments are then generated for each pixel corresponding to a 1 (one)
       in  the bitmap image.  These fragments are generated using the current
       raster z coordinate, color or color index, and current raster  texture
       coordinates.  They are then treated just as if they had been generated
       by a point, line, or polygon, including texture mapping,
       fogging, and all per-fragment  operations  such	as  alpha  and	depth
       testing.

       After  the  bitmap has been drawn, the x and y coordinates of the cur-
       rent raster position are offset by xmove and ymove.  No change is made
       to  the z coordinate of the current raster position, or to the current
       raster color, texture coordinates, or index.

NOTES
       To set a valid raster position outside the viewport, first set a valid
       raster  position	 inside the viewport, then call glBitmap with NULL as
       the bitmap parameter and with xmove and ymove set to  the  offsets  of
       the  new	 raster	 position.  This  technique is useful when panning an
       image around the viewport.

ERRORS
       GL_INVALID_VALUE is generated if width or height is negative.

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

ASSOCIATED GETS
       glGet with argument GL_CURRENT_RASTER_POSITION
       glGet with argument GL_CURRENT_RASTER_COLOR
       glGet with argument GL_CURRENT_RASTER_DISTANCE
       glGet with argument GL_CURRENT_RASTER_INDEX
       glGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
       glGet with argument GL_CURRENT_RASTER_POSITION_VALID

SEE ALSO
       glDrawPixels(3G),	glPixelStore(3G),	 glPixelTransfer(3G),
       glRasterPos(3G)




								 GLBITMAP(3G)