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vpRotate(3)           DragonFly 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_AXISX 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)

VolPack                                                            vpRotate(3)