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solid_angle.c
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Fri, Jul 18, 08:43

solid_angle.c
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#include <math.h>
#include "mex.h"
#include "matrix.h"
#include "geometry.h"
void
mexFunction (int nlhs, mxArray * plhs[], int nrhs, const mxArray * prhs[])
{
char str[256];
mxArray *sa;
double *v1, *v2, *v3, p1[3], p2[3], p3[3], *pnt, *tri, *sa_p;
int i1, i2, i3, npnt, ntri, i, on_triangle;
if (nrhs==2)
{
/* the input consists of a vertex array and a triangle array */
if (mxGetN(prhs[0])!=3)
mexErrMsgTxt ("Invalid dimension for input argument 1");
if (mxGetN(prhs[1])!=3)
mexErrMsgTxt ("Invalid dimension for input argument 2");
npnt = mxGetM(prhs[0]);
ntri = mxGetM(prhs[1]);
pnt = mxGetData (prhs[0]);
tri = mxGetData (prhs[1]);
sa = mxCreateDoubleMatrix (ntri, 1, mxREAL);
sa_p = mxGetData (sa);
/* compute the solid angle for all triangles */
for (i=0; i<ntri; i++)
{
i1 = (int)(tri[i]) - 1;
i2 = (int)(tri[i+ntri]) - 1;
i3 = (int)(tri[i+ntri+ntri]) - 1;
p1[0] = pnt[i1]; p1[1] = pnt[i1+npnt]; p1[2] = pnt[i1+npnt+npnt];
p2[0] = pnt[i2]; p2[1] = pnt[i2+npnt]; p2[2] = pnt[i2+npnt+npnt];
p3[0] = pnt[i3]; p3[1] = pnt[i3+npnt]; p3[2] = pnt[i3+npnt+npnt];
*(sa_p+i) = solang(p1, p2, p3, &on_triangle);
if (on_triangle)
*(sa_p+i) = mxGetNaN();
}
/* assign the output parameter */
plhs[0] = sa;
}
else if (nrhs==3)
{
/* the input consists of three vertices */
if (mxGetM(prhs[0])!=1 || mxGetN(prhs[0])!=3)
mexErrMsgTxt ("Invalid dimension for input argument 1");
if (mxGetM(prhs[1])!=1 || mxGetN(prhs[1])!=3)
mexErrMsgTxt ("Invalid dimension for input argument 2");
if (mxGetM(prhs[2])!=1 || mxGetN(prhs[2])!=3)
mexErrMsgTxt ("Invalid dimension for input argument 3");
v1 = mxGetData (prhs[0]);
v2 = mxGetData (prhs[1]);
v3 = mxGetData (prhs[2]);
sa = mxCreateDoubleMatrix (1, 1, mxREAL);
sa_p = mxGetData (sa);
/* compute the solid angle for a single triangle */
*(sa_p) = solang(v1, v2, v3, &on_triangle);
if (on_triangle)
*(sa_p) = mxGetNaN();
/* assign the output parameter */
plhs[0] = sa;
}
else
mexErrMsgTxt ("Invalid number of input arguments");
return;
}

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