NAME
vpTranspose - transpose a volume
SYNOPSIS
#include <volpack.h>
vpResult
vpTranspose(vpc, axis)
vpContext *vpc;
int axis;
ARGUMENTS
vpc VolPack context from vpCreateContext.
axis Axis which should have the smallest stride after transposing
(VP_X_AXIS, VP_Y_AXIS or VP_Z_AXIS).
DESCRIPTION
vpTranspose is used to transpose the 3D voxel array to optimize the
memory stride for a particular principal viewing axis. The intended
way to use this function is to set the viewing transformation, call
vpGeti with the VP_VIEW_AXIS argument to find the corresponding viewing
axis, and then call vpTranspose with that axis. Transposing the data
changes the arrangement of the data stored in the 3D voxel array. The
voxel stride state variables are updated to reflect this change, so the
viewing transformation does not need to be changed after transposing.
If the volume is already transposed for the requested axis then it
returns immediately without modifying the voxel array.
This function is useful only for rendering large 3D voxel arrays. This
function has no affect on the preclassified volume data.
STATE VARIABLES
Relevant variables may be retrieved with the following state variable
codes (see vpGeti(3)): VP_VIEW_AXIS, VP_VOXEL_XSTRIDE,
VP_VOXEL_YSTRIDE, VP_VOXEL_ZSTRIDE.
ERRORS
The normal return value is VP_OK. The following error return values
are possible:
VPERROR_BAD_OPTION
The axis argument is invalid.
VPERROR_BAD_VOLUME
The 3D voxel array is missing or invalid.
VPERROR_BAD_VOXEL
The voxel fields are incorrectly specified.
SEE ALSO
VolPack(3), vpCreateContext(3)