glBitmap

glBitmap

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 of 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 relative to the current raster position, and frame buffer pixels corresponding to ones in the bitmap are written using the current raster color or index. Frame buffer pixels corresponding to zeros in the bitmap are not modified.

glBitmap takes seven arguments. The first pair specify the width and height of the bitmap image. The second pair specify the location of the bitmap origin relative to the lower left corner of the bitmap image. The third pair of arguments specify 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 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

where (xr,yr) is the raster position and (xo,yo) is the bitmap origin. Fragments are then generated for each pixel corresponding to a 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, index, or texture coordinates.