glBitmap - draw a bitmap
void glBitmap(
GLsizei width,
GLsizei height,
GLfloat xorig,
GLfloat yorig,
GLfloat xmove,
GLfloat ymove,
const GLubyte *bitmap );
Specify the pixel width and height of the bitmap image.
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. Specify
the x and y offsets to be added to the current raster
position after the bitmap is drawn. Specifies the address
of the bitmap image.
A bitmap is a binary image. When drawn, the bitmap is
positioned relative to the current raster position, and
frame buffer pixels corresponding 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 glPixelTransfer() do not.
If the current raster position is invalid, glBitmap() is
ignored. Otherwise, the lower left corner of the bitmap
image is positioned at the window coordinates
x[w] = x[r] - x[o]
y[w] = y[r] - y[o]
where ( x[r] , y[r] ) is the raster position and ( x [o] ,
y[o] ) 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 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.
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.
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().
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
glDrawPixels(3), glPixelStore(3), glPixelTransfer(3),
glRasterPos(3)
glBitmap(3G)
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