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 vpRotate(3) FreeBSD Library Functions Manual vpRotate(3)

# NAME

vpRotate - multiply the current transformation matrix by a rotation matrix

# SYNOPSIS

#include <volpack.h>
vpResult
vpRotate(vpc, axis, degrees)
vpContext *vpc;
int axis;
double degrees;

# ARGUMENTS

vpc
VolPack context from vpCreateContext.
axis
Rotation axis code (VP_X_AXIS, VP_Y_AXIS or VP_Z_AXIS).
degrees
Number of degrees to rotate.

# DESCRIPTION

vpRotate is used to multiply the current transformation matrix by a 4-by-4 rotation matrix. The rotation axis must be one of the three principal viewing axes and is specified with one of the following codes: VP_X_AXIS X axis

VP_Y_AXIS Y axis

VP_Z_AXIS Z axis
The rotation angle is specified in degrees. A positive angle indicates a clockwise rotation when looking towards the positive direction along the axis. For an X-axis rotation, the rotation matrix is:
1 0 0 0

0 cos(d) sin(d) 0

0 -sin(d) cos(d) 0

0 0 0 1
where d stands for the degrees argument. For a Y-axis rotation, the rotation matrix is:
cos(d) 0 -sin(d) 0

0 1 0 0

sin(d) 0 cos(d) 0

0 0 0 1
For a Z-axis rotation, the rotation matrix is:
cos(d) sin(d) 0 0

-sin(d) cos(d) 0 0

0 0 1 0

0 0 0 1
Use vpCurrentMatrix to set the current transformation matrix. By default, the rotation matrix is post-multiplied (M = M*R where M is the current matrix and R is the rotation matrix). The VP_CONCAT_MODE option to vpSeti can be used to select pre-multiplication.

# STATE VARIABLES

The current matrix concatenation parameters can be retrieved with the following state variable codes (see vpGeti(3)): VP_CURRENT_MATRIX, VP_CONCAT_MODE.

# ERRORS

The normal return value is VP_OK. The following error return value is possible: