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glMultMatrix(3G)
Contents
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glMultMatrix, glMultMatrixd, glMultMatrixf - multiply the
current matrix with the specified matrix
void glMultMatrixd(
const GLdouble *m ); void glMultMatrixf(
const GLfloat *m );
Points to 16 consecutive values that are used as the elements
of a 4 times 4 column-major matrix.
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.
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 c[0] c[4] c[8]
c[12] v[0]
c[1] c[5] c[9] c[13] v[1]
times c[2] c[6] c[10] c[14]
v[2]
c[3] c[7] c[11] c[15] v[3]
Calling glMultMatrix() with an argument of "m" = m[0],
m[1], ..., m[15] replaces the current transformation with
(C times M) times 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]
times
times 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 'times' denotes matrix multiplication, and v is represented
as a 4 times 1 matrix.
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.
GL_INVALID_OPERATION is generated if glMultMatrix() is
executed between the execution of glBegin() and the corresponding
execution of glEnd().
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
glLoadIdentity(3), glLoadMatrix(3), glMatrixMode(3),
glPushMatrix(3)
glMultMatrix(3G)
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