2003-2004
Silicon Graphics, Inc.
glMultMatrix
3G
glMultMatrix
glMultMatrixf
glMultMatrixx
multiply the current matrix with the specified
matrix
C Specification
void glMultMatrixf
const GLfloat * m
void glMultMatrixx
const GLfixed * m
Parameters
m
Points to 16 consecutive values that are used as
the elements of a
4x4
column-major matrix.
Description
glMultMatrix
multiplies the current matrix with the one specified using
m,
and replaces the current matrix with the product.
The current matrix is determined by the current matrix mode (see
glMatrixMode).
It is either the projection matrix, modelview matrix, or the
texture matrix.
Examples
If the current matrix is C,
and the coordinates to be transformed are,
v=
v[0]
v[1]
v[2]
v[3]
,
then the current transformation is
Cxv
, or
(
c[0]
c[4]
c[8]
c[12]
c[1]
c[5]
c[9]
c[13]
c[2]
c[6]
c[10]
c[14]
c[3]
c[7]
c[11]
c[15]
)
x
(
v[0]
v[1]
v[2]
v[3]
)
Calling
glMultMatrix
with an argument of
m=
m[0],
m[1],
...
m[15]
replaces the current transformation with
CxM
xv
, or
(
c[0]
c[4]
c[8]
c[12]
c[1]
c[5]
c[9]
c[13]
c[2]
c[6]
c[10]
c[14]
c[3]
c[7]
c[11]
c[15]
)
x
(
m[0]
m[4]
m[8]
m[12]
m[1]
m[5]
m[9]
m[13]
m[2]
m[6]
m[10]
m[14]
m[3]
m[7]
m[11]
m[15]
)
x
(
v[0]
v[1]
v[2]
v[3]
)
Where
``x''
denotes matrix multiplication, and
v
is represented as a
4x1
matrix.
Notes
While the elements of the matrix may be specified with
fixed point or single precision, the GL may store or operate on
these values in less than single precision.
In many computer languages
4x4
arrays are represented in row-major order. The transformations
just described represent these matrices in column-major order.
The order of the multiplication is important. For example, if
the current transformation is a rotation, and
glMultMatrix
is called with a translation matrix, the translation is done
directly on the coordinates to be transformed, while the
rotation is done on the results of that translation.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glLoadIdentity,
glLoadMatrix,
glMatrixMode,
glPushMatrix
Copyright
Copyright 2003-2004
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.