intersect/intersect.c at master · threadmaster/intersect · GitHub

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#include"headers.h"
#include"prototypes.h"

intmain(){

doublex1, y1, x2, y2, x3, y3, x4, y4;

doubledeltamatrix[4], matA[4], matB[4];
double*dmat, *amat, *bmat;
doubleua, ub;

dmat=&deltamatrix[0];
amat=&matA[0];
bmat=&matB[0];

x1=-6.0;
y1=-2.0;
x2=5.0;
y2=1.0;
x3=-5.0;
y3=-3.0;
x4=6.0;
y4=2.0;

deltamatrix[0] =x2-x1;
deltamatrix[1] =x3-x4;
deltamatrix[2] =y2-y1;
deltamatrix[3] =y3-y4;

matA[0] =x3-x1;
matA[1] =x3-x4;
matA[2] =y3-y1;
matA[3] =y3-y4;

matB[0] =x2-x1;
matB[1] =x3-x1;
matB[2] =y2-y1;
matB[3] =y3-y1;

ua=det2D(amat)/det2D(dmat);
ub=det2D(bmat)/det2D(dmat);

printf("Ua = %f\n", ua);
printf("Ub = %f\n", ub);

if ( ua >= 1.0&&ub >= 1.0 ) {
printf(" -- Lines intersect -- \n");
 }
else {
printf(" -- Lines do not intersect -- \n");
 }

}