diff options
Diffstat (limited to 'src/math.c')
| -rw-r--r-- | src/math.c | 37 |
1 files changed, 29 insertions, 8 deletions
@@ -19,7 +19,8 @@ c3_group_rel_t *get_group_relative(char *id) { if(gr) return gr; } //if we got here, we need to make a new one. - assert(gr=malloc(sizeof(c3_group_rel_t)));//just exit on malloc error? sure... + gr=malloc(sizeof(c3_group_rel_t));//just exit on malloc error? sure... + assert(gr && "failed to malloc something I don't want to figure out how to work around if it doesn't malloc."); memset(gr,0,sizeof(c3_group_rel_t)); gr->s=(c3_t){1,1,1};//scale needs to be all 1s, since it is multiplied against the coordinates. gr->id=strdup(id);//don't forget to free this when it gets deleted. @@ -245,7 +246,7 @@ real distance3(c3_t p1,c3_t p2) { // <0 for P2 right of the line // See: Algorithm 1 "Area of Triangles and Polygons" inline int -isLeft( cs_t P0, cs_t P1, cs_t P2 ) +isLeft( c2_t P0, c2_t P1, c2_t P2 ) { return ( (P1.x - P0.x) * (P2.y - P0.y) - (P2.x - P0.x) * (P1.y - P0.y) ); @@ -256,20 +257,23 @@ isLeft( cs_t P0, cs_t P1, cs_t P2 ) // cn_PnPoly(): crossing number test for a point in a polygon // Input: P = a point, // V[] = vertex points of a polygon V[n+1] with V[n]=V[0] +// hacked on by epoch to make the previous statement automatic. i+1 changed to i+1%n // Return: 0 = outside, 1 = inside // This code is patterned after [Franklin, 2000] + +//pretending like this will work fine with a real instead of an int... probably fine. int -cn_PnPoly( cs_t P, cs_t *V, int n ) +cn_PnPoly( c2_t P, c2_t *V, int n ) { int cn = 0; // the crossing number counter // loop through all edges of the polygon for (int i=0; i<n; i++) { // edge from V[i] to V[i+1] - if (((V[i].y <= P.y) && (V[i+1].y > P.y)) // an upward crossing - || ((V[i].y > P.y) && (V[i+1].y <= P.y))) { // a downward crossing + if (((V[i].y <= P.y) && (V[i+1%n].y > P.y)) // an upward crossing + || ((V[i].y > P.y) && (V[i+1%n].y <= P.y))) { // a downward crossing // compute the actual edge-ray intersect x-coordinate - float vt = (float)(P.y - V[i].y) / (V[i+1].y - V[i].y); - if (P.x < V[i].x + vt * (V[i+1].x - V[i].x)) // P.x < intersect + float vt = (float)(P.y - V[i].y) / (V[i+1%n].y - V[i].y); + if (P.x < V[i].x + vt * (V[i+1%n].x - V[i].x)) // P.x < intersect ++cn; // a valid crossing of y=P.y right of P.x } } @@ -283,8 +287,9 @@ cn_PnPoly( cs_t P, cs_t *V, int n ) // Input: P = a point, // V[] = vertex points of a polygon V[n+1] with V[n]=V[0] // Return: wn = the winding number (=0 only when P is outside) + int -wn_PnPoly( cs_t P, cs_t *V, int n ) +wn_PnPoly( c2_t P, c2_t *V, int n ) { int wn = 0; // the winding number counter @@ -304,3 +309,19 @@ wn_PnPoly( cs_t P, cs_t *V, int n ) return wn; } //=================================================================== + +int epoch_PnPoly( c2_t P, c2_t *V, int n ) { + cs_t min,max; + int i; + min.x=V[0].x; + min.y=V[0].y; + max.x=V[0].x; + max.y=V[0].y; + for(i=0;i<n;i++) { + min.x=min(min.x,V[i].x); + max.x=max(max.x,V[i].x); + min.y=min(min.y,V[i].y); + max.y=max(max.y,V[i].y); + } + return (P.x <= max.x && P.x >= min.x && P.y >= min.y && P.y <= max.y); +} |