Converting c++ code to open gl

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  15 years ago

  by chrismatt83

  Chris Mathews

  , India

  Joined 15 years ago

  How can I run a C code on GPU using openGL?
  

  
  I  have this code in C and want it to run on GPU using openGL. I am just beginning to learn openGL.
  My main concern is how to shift the code from running on CPU to GPU. Any help is appreciated.
  

  
  void projectvolumeontoimagea (Volume* vol, CB_Image* cbi, float scale)
  {
     int i, j, k, p;
     float* img = (float*) vol->img;
     double wip[3];
     double *xip, *yip, *zip;
     double acc1[3],acc2[3],acc3[3];
  

  
     /* Rescale image (destructive rescaling) /
     for (i = 0; i < cbi->dim[0]cbi->dim[1]; i++) {
      cbi->img *= scale;
     }
  

  
     xip = (double) malloc (3vol->dim[0]sizeof(double));
     yip = (double) malloc (3vol->dim[1]sizeof(double));
     zip = (double) malloc (3vol->dim[2]*sizeof(double));
  

  
     /* Precompute stuff here /
     for (i = 0; i < vol->dim[0]; i++) {
      double a = (double) (vol->offset[0] + i * vol->pix_spacing[0]);
      xip[i3+0] = a * cbi->matrix[0];
      xip[i3+1] = a * cbi->matrix[4];
      xip[i3+2] = a * cbi->matrix[8];
     }
     for (j = 0; j < vol->dim[1]; j++) {
      double a = (double) (vol->offset[1] + j * vol->pixspacing[1]);
      yip[j*3+0] = a * cbi->matrix[1];
      yip[j*3+1] = a * cbi->matrix[5];
      yip[j*3+2] = a * cbi->matrix[9];
     }
     for (k = 0; k < vol->dim[2]; k++) {
      double a = (double) (vol->offset[2 ] + k * vol->pixspacing[2]);
      zip[k3+0] = a * cbi->matrix[2];
      zip[k3+1] = a * cbi->matrix[6];
      zip[k3+2] = a * cbi->matrix[10];
     }
     wip[0] = cbi->matrix[3];
     wip[1] = cbi->matrix[7];
     wip[2] = cbi->matrix[11];
     
     / Main loop /
     p = 0;
     for (k = 0; k < vol->dim[2]; k++) {
      rawvec3_add3 (acc1, wip, &zip[3k]);
      for (j = 0; j < vol->dim[1]; j++) {
          rawvec3add3 (acc2, acc1, &yip[3*j]);
          for (i = 0; i < vol->dim[0]; i++) {
           rawvec3add3 (acc3, acc2, &xip[3*i]);
           acc3[0] = cbi->ic[0] + acc3[0] / acc3[2];
           acc3[1] = cbi->ic[1] + acc3[1] / acc3[2];
           img[p++] += getpixelvalue (cbi, acc3[0], acc3[1]);
          }
      }
     }
  }
  

  
  void
  rawvec3_add3 (double* v1, const double* v2, const double* v3)
  {
     int i;
     for (i = 0; i < 3; i++) {
      v1 = v2 + v3;
     }
  }
  

  
  float getpixelvalue (CB_Image* cbi, double r, double c)
  {
     int rr, cc;
  

  
     rr = roundint (r);
     if (rr < 0 || rr >= cbi->dim[0]) return 0.0;
     cc = roundint (c);
     if (cc < 0 || cc >= cbi->dim[1]) return 0.0;
     return cbi->img[rr*cbi-> dim[0] + cc];
  }

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