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vpRotate

vpRotate

Section: C Library Functions (3) Updated:
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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:
VPERROR_BAD_OPTION
The axis argument is invalid.
 

SEE ALSO

VolPack(3), vpCreateContext(3), vpCurrentMatrix(3)


 

Index

NAME
SYNOPSIS
ARGUMENTS
DESCRIPTION
STATE VARIABLES
ERRORS
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 21:54:11 GMT, April 16, 2011