GLMULTMATRIX(3G)GLMULTMATRIX(3G)NAME
glMultMatrixd, glMultMatrixf - multiply the current matrix with the
specified matrix
C SPECIFICATION
void glMultMatrixd( const GLdouble *m )
void glMultMatrixf( const GLfloat *m )
delim $$
PARAMETERS
m Points to 16 consecutive values that are used as the elements of
a $4 ~times~ 4$ column-major matrix.
DESCRIPTIONglMultMatrix 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 $C ~times~ v$, or
down 130 {{ left ( matrix {
ccol { c[0] above c[1] above c[2] above c[3] }
ccol { c[4] above c[5] above c[6] above c[7] }
ccol { c[8] above c[9] above c[10] above c[11] }
ccol { c[12]~ above c[13]~ above c[14]~ above c[15]~ } } right ) }
~~ times ~~ {left ( matrix { ccol { v[0]~ above v[1]~ above v[2]~ above
v[3]~ } } right )} }
Calling glMultMatrix with an argument of $"m" ~=~ m[0], m[1], ...,
m[15]$ replaces the current transformation with $(C ~times~ M) ~times~
v$, or
down 130 {{ left ( matrix {
ccol { c[0] above c[1] above c[2] above c[3] }
ccol { c[4] above c[5] above c[6] above c[7] }
ccol { c[8] above c[9] above c[10] above c[11] }
ccol { c[12]~ above c[13]~ above c[14]~ above c[15]~ } } right ) }
~~ times ~~ { left ( matrix {
ccol { m[0] above m[1] above m[2] above m[3] }
ccol { m[4] above m[5] above m[6] above m[7] }
ccol { m[8] above m[9] above m[10] above m[11] }
ccol { m[12]~ above m[13]~ above m[14]~ above m[15]~ } } right ) }
~~ times ~~ {left ( matrix { ccol { v[0]~ above v[1]~ above v[2]~ above
v[3]~ } } right )} }
Where '$times$' denotes matrix multiplication, and $v$ is represented
as a $4 ~times~ 1$ matrix.
NOTES
While the elements of the matrix may be specified with single or double
precision, the GL may store or operate on these values in less than
single precision.
In many computer languages $4 ~times~ 4$ 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.
ERRORS
GL_INVALID_OPERATION is generated if glMultMatrix is executed between
the execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGet with argument GL_MATRIX_MODE
glGet with argument GL_COLOR_MATRIX
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
SEE ALSOglLoadIdentity(3G), glLoadMatrix(3G), glMatrixMode(3G),
glPushMatrix(3G)
March 1, 2011
