GLBITMAP()GLBITMAP()NAMEglBitmap - draw a bitmap
C SPECIFICATION
void glBitmap( GLsizei width,
GLsizei height,
GLfloat xorig,
GLfloat yorig,
GLfloat xmove,
GLfloat ymove,
const GLubyte *bitmap )
delim $$
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 rela‐
tive 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 location 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 glPixel‐
Transfer do not.
If the current raster position is invalid, glBitmap is ignored. Other‐
wise, the lower left corner of the bitmap image is positioned at the
window coordinates
$ x sub w ~=~ ⌊ ~ x sub r ~-~ x sub o ~ ⌋ $
$ y sub w ~=~ ⌊ ~ y sub r ~-~ y sub o ~ ⌋ $
where $ ( x sub r , y sub r ) $ is the raster position and $ ( x sub o
, y sub o ) $ is the bitmap origin. Fragments are then generated for
each pixel corresponding to a 1 (one) in the bitmap image. These frag‐
ments 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 poly‐
gon, including texture mapping,
fogging, and all per-fragment operations such as alpha and depth test‐
ing.
After the bitmap has been drawn, the x and y coordinates of the current
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_INDEX
glGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
glGet with argument GL_CURRENT_RASTER_POSITION_VALID
SEE ALSO
glDrawPixels, glPixelStore, glPixelTransfer, glRasterPos
GLBITMAP()
