The XVOLUME_ROTATE procedure is used to programmatically rotate the volume currently displayed in XVOLUME. XVOLUME must be called prior to calling XVOLUME_ROTATE. This procedure can be used to create animations of volumes and isosurfaces.
This routine is written in the IDL language. Its source code can be found in the file
xvolume_rotate.pro in the
lib/utilities subdirectory of the IDL distribution.
XVOLUME_ROTATE, Axis, Angle [, /PREMULTIPLY]
A 3-element vector of the form [x, y, z] describing the axis about which the model is to be rotated.
The amount of rotation, measured in degrees.
Set this keyword to cause the rotation matrix specified by Axis and Angle to be pre-multiplied to the model's transformation matrix. By default, the rotation matrix is post-multiplied.
The following example creates an animation of the volume currently displayed in XVOLUME. It does this by rotating the volume through 360 degrees in increments of 10 degrees using XVOLUME_ROTATE, and writing the volume to a BMP file for each increment using XVOLUME_WRITE_IMAGE. It then loops through the images and uses TV to display each image.
First, display a volume as follows:
; Create a volume: vol = BYTSCL(RANDOMU((SEED=0),5,5,5)) vol = CONGRID(vol, 30,30,30) ; Display volume: XVOLUME, vol
Now, use the XVOLUME interface to modify the orientation and appearance of the volume or isosurface as desired. Once you have the volume or isosurface displayed the way you want it, run the following program:
PRO spin_volume inc = 10. ; degrees. ; Create images FOR i=0,(360./inc)-2 DO BEGIN XVOLUME_WRITE_IMAGE, $ 'spin' + STRCOMPRESS(i, /REMOVE_ALL) + '.bmp', 'bmp' XVOLUME_ROTATE, [0,0,1], inc, /PREMULTIPLY ENDFOR XVOLUME_ROTATE, [0,0,1], inc, /PREMULTIPLY ; Read images img = READ_BMP('spin0.bmp') siz = SIZE(img, /DIM) arr = BYTARR(3, siz, siz, 360./inc-1) FOR i=0,360./inc-2 DO BEGIN img = READ_BMP( $ 'spin' + STRCOMPRESS(i, /REMOVE_ALL) + '.bmp', /RGB) arr[0,0,0, i] = img PRINT, i ENDFOR ; Display animation FOR i=0,2 DO BEGIN ; num rotations FOR j=0,(360./inc)-2 DO BEGIN TV, arr[*,*,*,j], /TRUE ENDFOR ENDFOR TV, arr[*,*,*,0], /TRUE END