glBitmap
[New
- Windows 95, OEM Service Release 2]
The glBitmap
function draws a bitmap.
void glBitmap(
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GLsizei width, |
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GLsizei height, |
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GLfloat xorig, |
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GLfloat yorig, |
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GLfloat xmove, |
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GLfloat ymove, |
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const GLubyte * bitmap |
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); |
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Parameters
width,
height
The pixel
width and height of the bitmap image.
xorig,
yorig
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 directions being the positive axes.
xmove,
ymove
The x
and y offsets to be added to the current raster position after the bitmap
is drawn.
bitmap
The address
of the bitmap image.
Remarks
A bitmap is a
binary image. When drawn, the bitmap is positioned relative to the current
raster position, and frame buffer pixels corresponding to 1s in the bitmap are
written using the current raster color or index. Frame-buffer pixels
corresponding to zeros in the bitmap are not modified.
The bitmap
image is interpreted like image data for the glDrawPixels function, with width
and height corresponding to the width and height arguments of that
function, and with type set to GL_BITMAP and format set to
GL_COLOR_INDEX. Modes you specify using glPixelStore affect the interpretation
of bitmap image data; modes you specify 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 following window
coordinates:
x (w) = x (r) - x (o)
y (w) = y (r) - y (o)
In these
coordinates, (xr, yr) is the raster position, and (xo, yo) is the
bitmap origin. Fragments are then generated for each pixel corresponding to a 1
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, index, or texture coordinates.
The following
functions retrieve information related to the glBitmap function:
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
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_VALUE
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width or height is negative. |
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GL_INVALID_OPERATION
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glBitmap is called between a call to glBegin and the
corresponding call to glEnd. |
See Also