wolffd@0: /* This is based on
wolffd@0: http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_external/ch04cr12.shtml
wolffd@0: 
wolffd@0: See rectintSparse.m for the matlab version of this code.
wolffd@0: 
wolffd@0: */
wolffd@0: 
wolffd@0: #include <math.h> /* Needed for the ceil() prototype. */
wolffd@0: #include "mex.h"
wolffd@0: #include <stdio.h>
wolffd@0: 
wolffd@0: /* If you are using a compiler that equates NaN to be zero, you 
wolffd@0:  * must compile this example using the flag  -DNAN_EQUALS_ZERO.
wolffd@0:  * For example:
wolffd@0:  *
wolffd@0:  *     mex -DNAN_EQUALS_ZERO fulltosparse.c
wolffd@0:  *
wolffd@0:  * This will correctly define the IsNonZero macro for your C
wolffd@0:  * compiler.
wolffd@0:  */
wolffd@0: 
wolffd@0: #if defined(NAN_EQUALS_ZERO)
wolffd@0: #define IsNonZero(d) ((d) != 0.0 || mxIsNaN(d))
wolffd@0: #else
wolffd@0: #define IsNonZero(d) ((d) != 0.0)
wolffd@0: #endif
wolffd@0: 
wolffd@0: #define MAX(x,y)  ((x)>(y) ? (x) : (y))
wolffd@0: #define MIN(x,y)  ((x)<(y) ? (x) : (y))
wolffd@0: 
wolffd@0: void mexFunction(
wolffd@0:         int nlhs,       mxArray *plhs[],
wolffd@0:         int nrhs, const mxArray *prhs[]
wolffd@0:         )
wolffd@0: {
wolffd@0:   /* Declare variables. */
wolffd@0:   int j,k,m,n,nzmax,*irs,*jcs, *irs2, *jcs2;
wolffd@0:   double *overlap, *overlap2, tmp, areaA, areaB;
wolffd@0:   double percent_sparse;
wolffd@0:   double *leftA, *rightA, *topA, *bottomA;
wolffd@0:   double *leftB, *rightB, *topB, *bottomB;
wolffd@0:   double *verbose;
wolffd@0: 
wolffd@0:   /* Get the size and pointers to input data. */
wolffd@0:   m = MAX(mxGetM(prhs[0]), mxGetN(prhs[0]));
wolffd@0:   n = MAX(mxGetM(prhs[4]), mxGetN(prhs[4]));
wolffd@0:   /* printf("A=%d, B=%d\n", m, n); */
wolffd@0: 
wolffd@0:   leftA = mxGetPr(prhs[0]);
wolffd@0:   rightA = mxGetPr(prhs[1]);
wolffd@0:   topA = mxGetPr(prhs[2]);
wolffd@0:   bottomA = mxGetPr(prhs[3]);
wolffd@0: 
wolffd@0:   leftB = mxGetPr(prhs[4]);
wolffd@0:   rightB = mxGetPr(prhs[5]);
wolffd@0:   topB = mxGetPr(prhs[6]);
wolffd@0:   bottomB = mxGetPr(prhs[7]);
wolffd@0: 
wolffd@0:   verbose = mxGetPr(prhs[8]);
wolffd@0: 
wolffd@0:     /* Allocate space for sparse matrix. 
wolffd@0:      * NOTE:  Assume at most 20% of the data is sparse.  Use ceil
wolffd@0:      * to cause it to round up. 
wolffd@0:      */
wolffd@0: 
wolffd@0:   percent_sparse = 0.01;
wolffd@0:   nzmax = (int)ceil((double)m*(double)n*percent_sparse);
wolffd@0: 
wolffd@0:   plhs[0] = mxCreateSparse(m,n,nzmax,0);
wolffd@0:   overlap  = mxGetPr(plhs[0]);
wolffd@0:   irs = mxGetIr(plhs[0]);
wolffd@0:   jcs = mxGetJc(plhs[0]);
wolffd@0: 
wolffd@0:   plhs[1] = mxCreateSparse(m,n,nzmax,0);
wolffd@0:   overlap2  = mxGetPr(plhs[1]);
wolffd@0:   irs2 = mxGetIr(plhs[1]);
wolffd@0:   jcs2 = mxGetJc(plhs[1]);
wolffd@0: 
wolffd@0:     
wolffd@0:   /* Assign nonzeros. */
wolffd@0:   k = 0; 
wolffd@0:   for (j = 0; (j < n); j++) {
wolffd@0:     int i;
wolffd@0:     jcs[j] = k; 
wolffd@0:     jcs2[j] = k; 
wolffd@0:     for (i = 0; (i < m); i++) {
wolffd@0:       tmp = (MAX(0, MIN(rightA[i], rightB[j]) - MAX(leftA[i], leftB[j]) )) * 
wolffd@0: 	(MAX(0, MIN(topA[i], topB[j]) - MAX(bottomA[i], bottomB[j]) ));
wolffd@0:       
wolffd@0:       if (*verbose) {
wolffd@0: 	printf("j=%d,i=%d,tmp=%5.3f\n", j,i,tmp);
wolffd@0:       }
wolffd@0: 
wolffd@0:       if (IsNonZero(tmp)) {
wolffd@0: 
wolffd@0:         /* Check to see if non-zero element will fit in 
wolffd@0:          * allocated output array.  If not, increase
wolffd@0:          * percent_sparse by 20%, recalculate nzmax, and augment
wolffd@0:          * the sparse array.
wolffd@0:          */
wolffd@0:         if (k >= nzmax) {
wolffd@0:           int oldnzmax = nzmax;
wolffd@0:           percent_sparse += 0.2;
wolffd@0:           nzmax = (int)ceil((double)m*(double)n*percent_sparse);
wolffd@0: 
wolffd@0:           /* Make sure nzmax increases atleast by 1. */
wolffd@0:           if (oldnzmax == nzmax) 
wolffd@0:             nzmax++;
wolffd@0: 	  printf("reallocating from %d to %d\n", oldnzmax, nzmax);
wolffd@0: 
wolffd@0:           mxSetNzmax(plhs[0], nzmax); 
wolffd@0:           mxSetPr(plhs[0], mxRealloc(overlap, nzmax*sizeof(double)));
wolffd@0:           mxSetIr(plhs[0], mxRealloc(irs, nzmax*sizeof(int)));
wolffd@0:           overlap  = mxGetPr(plhs[0]);
wolffd@0:           irs = mxGetIr(plhs[0]);
wolffd@0: 
wolffd@0:           mxSetNzmax(plhs[1], nzmax); 
wolffd@0:           mxSetPr(plhs[1], mxRealloc(overlap2, nzmax*sizeof(double)));
wolffd@0:           mxSetIr(plhs[1], mxRealloc(irs2, nzmax*sizeof(int)));
wolffd@0:           overlap2  = mxGetPr(plhs[1]);
wolffd@0:           irs2 = mxGetIr(plhs[1]);
wolffd@0:         }
wolffd@0: 
wolffd@0:         overlap[k] = tmp;
wolffd@0:         irs[k] = i;
wolffd@0: 	
wolffd@0: 	areaA = (rightA[i]-leftA[i])*(topA[i]-bottomA[i]);
wolffd@0: 	areaB = (rightB[j]-leftB[j])*(topB[j]-bottomB[j]);
wolffd@0: 	overlap2[k] = MIN(tmp/areaA, tmp/areaB);
wolffd@0: 	irs2[k] = i;
wolffd@0: 
wolffd@0:         k++;
wolffd@0:       } /* IsNonZero */
wolffd@0:     } /* for i */
wolffd@0:   }
wolffd@0:   jcs[n] = k;
wolffd@0:   jcs2[n] = k;
wolffd@0:   
wolffd@0: }
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: