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glRasterPos(3G)
NAME
glRasterPos, glRasterPos2d, glRasterPos2f, glRasterPos2i, glRasterPos2s,
glRasterPos3d, glRasterPos3f, glRasterPos3i, glRasterPos3s, glRasterPos4d,
glRasterPos4f, glRasterPos4i, glRasterPos4s, glRasterPos2dv,
glRasterPos2fv, glRasterPos2iv, glRasterPos2sv, glRasterPos3dv,
glRasterPos3fv, glRasterPos3iv, glRasterPos3sv, glRasterPos4dv,
glRasterPos4fv, glRasterPos4iv, glRasterPos4sv - specify the raster
position for pixel operations
SYNOPSIS
void glRasterPos2d(
GLdouble x,
GLdouble y );
void glRasterPos2f(
GLfloat x,
GLfloat y );
void glRasterPos2i(
GLint x,
GLint y );
void glRasterPos2s(
GLshort x,
GLshort y );
void glRasterPos3d(
GLdouble x,
GLdouble y,
GLdouble z );
void glRasterPos3f(
GLfloat x,
GLfloat y,
GLfloat z );
void glRasterPos3i(
GLint x,
GLint y,
GLint z );
void glRasterPos3s(
GLshort x,
GLshort y,
GLshort z );
void glRasterPos4d(
GLdouble x,
GLdouble y,
GLdouble z,
GLdouble w );
void glRasterPos4f(
GLfloat x,
GLfloat y,
GLfloat z,
GLfloat w );
void glRasterPos4i(
GLint x,
GLint y,
GLint z,
GLint w );
void glRasterPos4s(
GLshort x,
GLshort y,
GLshort z,
GLshort w );
PARAMETERS
x, y, z, w
Specify the x, y, z, and w object coordinates (if present) for the
raster position.
SYNOPSIS
void glRasterPos2dv(
const GLdouble *v );
void glRasterPos2fv(
const GLfloat *v );
void glRasterPos2iv(
const GLint *v );
void glRasterPos2sv(
const GLshort *v );
void glRasterPos3dv(
const GLdouble *v );
void glRasterPos3fv(
const GLfloat *v );
void glRasterPos3iv(
const GLint *v );
void glRasterPos3sv(
const GLshort *v );
void glRasterPos4dv(
const GLdouble *v );
void glRasterPos4fv(
const GLfloat *v );
void glRasterPos4iv(
const GLint *v );
void glRasterPos4sv(
const GLshort *v );
PARAMETERS
v Specifies a pointer to an array of two, three, or four elements,
specifying x, y, z, and w coordinates, respectively.
DESCRIPTION
The GL maintains a 3D position in window coordinates. This position, called
the raster position, is used to position pixel and bitmap write operations.
It is maintained with subpixel accuracy. See glBitmap(), glDrawPixels(),
and glCopyPixels().
The current raster position consists of three window coordinates (x, y, z),
a clip coordinate value (w), an eye coordinate distance, a valid bit, and
associated color data and texture coordinates. The w coordinate is a clip
coordinate, because w is not projected to window coordinates.
glRasterPos4() specifies object coordinates x, y, z, and w explicitly.
glRasterPos3() specifies object coordinate x, y, and z explicitly, while w
is implicitly set to 1. glRasterPos2() uses the argument values for x and
y while implicitly setting z and w to 0 and 1.
The object coordinates presented by glRasterPos() are treated just like
those of a glVertex() command: They are transformed by the current
modelview and projection matrices and passed to the clipping stage. If the
vertex is not culled, then it is projected and scaled to window
coordinates, which become the new current raster position, and the
GL_CURRENT_RASTER_POSITION_VALID option is set. If the vertex is culled,
then the valid bit is cleared and the current raster position and
associated color and texture coordinates are undefined.
The current raster position also includes some associated color data and
texture coordinates. If lighting is enabled, then GL_CURRENT_RASTER_COLOR
(in RGBA mode) or GL_CURRENT_RASTER_INDEX (in color index mode) is set to
the color produced by the lighting calculation (see glLight(),
glLightModel(), and glShadeModel()). If lighting is disabled, current color
(in RGBA mode, state variable GL_CURRENT_COLOR) or color index (in color
index mode, state variable GL_CURRENT_INDEX) is used to update the current
raster color.
Likewise, GL_CURRENT_RASTER_TEXTURE_COORDS is updated as a function of
GL_CURRENT_TEXTURE_COORDS, based on the texture matrix and the texture
generation functions (see glTexGen()). Finally, the distance from the
origin of the eye coordinate system to the vertex as transformed by only
the modelview matrix replaces GL_CURRENT_RASTER_DISTANCE.
Initially, the current raster position is (0, 0, 0, 1), the current raster
distance is 0, the valid bit is set, the associated RGBA color is (1, 1, 1,
1), the associated color index is 1, and the associated texture coordinates
are (0, 0, 0, 1). In RGBA mode, GL_CURRENT_RASTER_INDEX is always 1; in
color index mode, the current raster RGBA color always maintains its
initial value.
NOTES
The raster position is modified both by glRasterPos() and by glBitmap().
When the raster position coordinates are invalid, drawing commands that are
based on the raster position are ignored (that is, they do not result in
changes to GL state).
Calling glDrawElements(), or glDrawRangeElements() may leave the current
color or index indeterminate. If glRasterPos() is executed while the
current color or index is indeterminate, the current raster color or
current raster index remains indeterminate.
To set a valid raster position outside the viewport, first set a valid
raster position, then call glBitmap() with NULL as the bitmap parameter.
When the GL_ARB_imaging extension is supported, there are distinct raster
texture coordinates for each texture unit. Each texture unit's current
ratster texture coordinates are updated by glRasterPos().
ERRORS
GL_INVALID_OPERATION is generated if glRasterPos() 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_POSITION_VALID
glGet() with argument GL_CURRENT_RASTER_DISTANCE
glGet() with argument GL_CURRENT_RASTER_COLOR
glGet() with argument GL_CURRENT_RASTER_INDEX
glGet() with argument GL_CURRENT_RASTER_TEXTURE_COORDS
SEE ALSO
glBitmap(3), glCopyPixels(3), glDrawArrays(3), glDrawElements(3),
glDrawRangeElements(3), glDrawPixels(3), glTexCoord(3), glTexGen(3),
glVertex(3)
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Index for
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Alphabetical
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