NAME

       vpGetImage - get a field of the intermediate image

SYNOPSIS

       #include <volpack.h>

       vpResult
       vpGetImage(vpc, image, width, height, scan_bytes, pixel_type, image_type)
           vpContext *vpc;
           void *image;
           int width, height;
           int scan_bytes;
           int pixel_type, image_type;

ARGUMENTS

       vpc    VolPack context from vpCreateContext.

       image  2D array for storing result image.

       width  Width of array in pixels.

       height Height of array in pixels.

       scan_bytes
              Number of bytes per scanline in array.

       pixel_type
              Code indicating the format of each pixel in the array.

       image_type
              Code indicating the source of the image data (VP_IMAGE_BUFFER or VP_SHADOW_BUFFER).

DESCRIPTION

       This is a debugging function.  It is used to retrieve the contents of one of the temporary
       rendering buffers used during rendering, namely  the  intermediate  image  or  the  shadow
       buffer.  Rendering consists of two stages: the volume is resampled and composited into the
       intermediate image to produce a distorted volume  rendering,  and  then  the  intermediate
       image  is  warped  into the final image.  If shadows are enabled then the shadow buffer is
       used during the first stage to incrementally compute which voxels are illuminated  by  the
       light  source.   This  function returns images produced during the first stage, before the
       final warp.

       This function may  be  called  after  a  call  to  one  of  the  rendering  routines  (see
       vpRenderRawVolume(3)).   If  the  image_type argument is VP_IMAGE_BUFFER then data will be
       copied from the intermediate image.  The pixel_type argument specifies what information to
       copy  and  the  format  for storing the data in the output array.  The possible values for
       pixel_type are the same as for the pixel_type argument to vpSetImage.  For  instance,  use
       VP_LUMINANCE  to  extract  the  grayscale  intensity (assuming the current shader produces
       grayscale pixels).

       If the image_type argument is VP_SHADOW_BUFFER then data will be copied  from  the  shadow
       buffer.   The  only valid option for pixel_type is VP_ALPHA, since no color information is
       stored in the shadow buffer.

       See vpSetImage for details on the pixel formats, the layout of the output array,  and  the
       remaining arguments.

       To  find the required size for the result array, use vpGeti with the VP_INTERMEDIATE_WIDTH
       and  VP_INTERMEDIATE_HEIGHT  options  (when  image_type   is   VP_IMAGE_BUFFER)   or   the
       VP_SHADOW_WIDTH and VP_SHADOW_HEIGHT options (when image_type is VP_SHADOW_BUFFER).

ERRORS

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

       VPERROR_BAD_SIZE
              The destination array size is incorrect or there is no intermediate image.

       VPERROR_BAD_OPTION
              The field argument is invalid.

SEE ALSO

       VolPack(3), vpRenderRawVolume(3), vpGeti(3)