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/* Memorybuffer2Texture.cc -- Minimal example of how to
* pass a pointer to a memory buffer to Psychtoolbox,
* so that one can create a texture out of its content.
*
* This simple example creates a 640 x 480 pixels color
* image in a memory buffer and returns a pointer to it
* to Octave, encoded as a double value: The way we encode
* the pointer as double may look clumsy, but it guarantees
* that it works even on 64-Bit systems.
*
* Compile with: mkoctfile Memorybuffer2Texture.cc
* Then run Memorybuffer2TextureDemo.m
*
* Written by Mario Kleiner.
*/
#include <stdlib.h>
#include "octave/oct.h"
/* Byte array with 640 x 480 greyscale pixels */
static float rawimage[640*480*3];
/* Definition of a 64-bit number: Operating system dependend: */
#ifndef __WIN32__
/* Unix style: */
typedef unsigned long long psych_uint64;
#else
/* Microsoft Windows style: */
typedef LONG psych_uint64;
#endif
/* Convert a memory address pointer into a double value: */
double PtrToDouble(void* ptr)
{
volatile psych_uint64 ival = (psych_uint64) ptr;
volatile double* dptr = (double*) &ival;
volatile double outval = *dptr;
return(outval);
}
DEFUN_DLD(Memorybuffer2Texture, inargs, nargout,
"MemoryBuffer2Texture -- Octave version\n"
"See MemoryBuffer2TextureDemo.m for help and info.")
{
octave_value_list outarg;
int x,y, pos;
double dblimgptr;
/* Fill our rawimage image array with content: */
pos = 0;
for(y=0; y<480; y++)
for (x=0; x<640; x++) {
// Red channel:
rawimage[pos++] = (float)x/640;
// Green channel:
rawimage[pos++] = (float)y/480;
// Blue channel:
rawimage[pos++] = 0;
}
/* Convert our memory pointer to something Psychtoolbox
understands, i.e., convert it into a double value:
*/
dblimgptr = PtrToDouble((void*) &rawimage);
// printf("InTexPtr %p --> %.20e", (void*) &rawimage, dblimgptr);
/* Return double-encoded pointer to Octave: */
outarg(0) = octave_value(dblimgptr);
return(outarg);
}
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