fglMultMatrix(3G) OpenGL Reference fglMultMatrix(3G)NAME
fglMultMatrixd, fglMultMatrixf - multiply the current matrix with the
specified matrix
FORTRAN SPECIFICATION
SUBROUTINE fglMultMatrixd( CHARACTER*8 m )
SUBROUTINE fglMultMatrixf( CHARACTER*8 m )
PARAMETERS
m Points to 16 consecutive values that are used as the elements of a
4 x 4 column-major matrix.
DESCRIPTION
fglMultMatrix 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
fglMatrixMode). 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 x v, or
(c[0] c[4] c[8] c[12] ) (v[0] )
| | | |
c[1] c[5] c[9] c[13] v[1]
| | | |
x
|c[2] c[6] c[10] c[14] | |v[2] |
| | | |
c[3] c[7] c[11] c[15] v[3]
( ) ( )
Calling fglMultMatrix with an argument of m = m[0],m[1],...,m[15]
replaces the current transformation with (C x M) x v, or
(c[0] c[4] c[8] c[12] ) (m[0] m[4] m[8] m[12] ) (v[0] )
| | | | | |
c[1] c[5] c[9] c[13] m[1] m[5] m[9] m[13] v[1]
| | | | | |
x x
|c[2] c[6] c[10] c[14] | |m[2] m[6] m[10] m[14] | |v[2] |
| | | | | |
c[3] c[7] c[11] c[15] m[3] m[7] m[11] m[15] v[3]
( ) ( ) ( )
Where 'x' denotes matrix multiplication, and v is represented as a 4 x 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.
Page 1
fglMultMatrix(3G) OpenGL Reference fglMultMatrix(3G)
In many computer languages 4 x 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 fglMultMatrix
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 fglMultMatrix is executed between
the execution of fglBegin and the corresponding execution of fglEnd.
ASSOCIATED GETS
fglGet with argument GL_MATRIX_MODE
fglGet with argument GL_COLOR_MATRIX
fglGet with argument GL_MODELVIEW_MATRIX
fglGet with argument GL_PROJECTION_MATRIX
fglGet with argument GL_TEXTURE_MATRIX
SEE ALSO
fglLoadIdentity, fglLoadMatrix, fglMatrixMode, fglPushMatrix
Page 2
