+/*
+Copyright (C) 2003, 2010 - Wolfire Games
+Copyright (C) 2010-2016 - Lugaru contributors (see AUTHORS file)
+
+This file is part of Lugaru.
+
+Lugaru is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+Lugaru is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Lugaru. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "Math/XYZ.hpp"
+
+bool PointInTriangle(XYZ *p, XYZ normal, XYZ *p1, XYZ *p2, XYZ *p3)
+{
+ static float u0, u1, u2;
+ static float v0, v1, v2;
+ static float a, b;
+ static float max;
+ static int i, j;
+ static bool bInter = 0;
+ static float pointv[3];
+ static float p1v[3];
+ static float p2v[3];
+ static float p3v[3];
+ static float normalv[3];
+
+ bInter = 0;
+
+ pointv[0] = p->x;
+ pointv[1] = p->y;
+ pointv[2] = p->z;
+
+
+ p1v[0] = p1->x;
+ p1v[1] = p1->y;
+ p1v[2] = p1->z;
+
+ p2v[0] = p2->x;
+ p2v[1] = p2->y;
+ p2v[2] = p2->z;
+
+ p3v[0] = p3->x;
+ p3v[1] = p3->y;
+ p3v[2] = p3->z;
+
+ normalv[0] = normal.x;
+ normalv[1] = normal.y;
+ normalv[2] = normal.z;
+
+#define ABS(X) (((X)<0.f)?-(X):(X) )
+#define MAX(A, B) (((A)<(B))?(B):(A))
+ max = MAX(MAX(ABS(normalv[0]), ABS(normalv[1])), ABS(normalv[2]));
+#undef MAX
+ if (max == ABS(normalv[0])) {
+ i = 1; // y, z
+ j = 2;
+ }
+ if (max == ABS(normalv[1])) {
+ i = 0; // x, z
+ j = 2;
+ }
+ if (max == ABS(normalv[2])) {
+ i = 0; // x, y
+ j = 1;
+ }
+#undef ABS
+
+ u0 = pointv[i] - p1v[i];
+ v0 = pointv[j] - p1v[j];
+ u1 = p2v[i] - p1v[i];
+ v1 = p2v[j] - p1v[j];
+ u2 = p3v[i] - p1v[i];
+ v2 = p3v[j] - p1v[j];
+
+ if (u1 > -1.0e-05f && u1 < 1.0e-05f) { // == 0.0f)
+ b = u0 / u2;
+ if (0.0f <= b && b <= 1.0f) {
+ a = (v0 - b * v2) / v1;
+ if ((a >= 0.0f) && (( a + b ) <= 1.0f))
+ bInter = 1;
+ }
+ } else {
+ b = (v0 * u1 - u0 * v1) / (v2 * u1 - u2 * v1);
+ if (0.0f <= b && b <= 1.0f) {
+ a = (u0 - b * u2) / u1;
+ if ((a >= 0.0f) && (( a + b ) <= 1.0f ))
+ bInter = 1;
+ }
+ }
+
+ return bInter;
+}
+
+bool LineFacet(XYZ p1, XYZ p2, XYZ pa, XYZ pb, XYZ pc, XYZ *p)
+{
+ static float d;
+ static float denom, mu;
+ static XYZ n;
+
+ //Calculate the parameters for the plane
+ n.x = (pb.y - pa.y) * (pc.z - pa.z) - (pb.z - pa.z) * (pc.y - pa.y);
+ n.y = (pb.z - pa.z) * (pc.x - pa.x) - (pb.x - pa.x) * (pc.z - pa.z);
+ n.z = (pb.x - pa.x) * (pc.y - pa.y) - (pb.y - pa.y) * (pc.x - pa.x);
+ Normalise(&n);
+ d = - n.x * pa.x - n.y * pa.y - n.z * pa.z;
+
+ //Calculate the position on the line that intersects the plane
+ denom = n.x * (p2.x - p1.x) + n.y * (p2.y - p1.y) + n.z * (p2.z - p1.z);
+ if (fabs(denom) < 0.0000001) // Line and plane don't intersect
+ return 0;
+ mu = - (d + n.x * p1.x + n.y * p1.y + n.z * p1.z) / denom;
+ p->x = p1.x + mu * (p2.x - p1.x);
+ p->y = p1.y + mu * (p2.y - p1.y);
+ p->z = p1.z + mu * (p2.z - p1.z);
+ if (mu < 0 || mu > 1) // Intersection not along line segment
+ return 0;
+
+ if (!PointInTriangle( p, n, &pa, &pb, &pc)) {
+ return 0;
+ }
+
+ return 1;
+}
+
+float LineFacetd(XYZ p1, XYZ p2, XYZ pa, XYZ pb, XYZ pc, XYZ *p)
+{
+ static float d;
+ static float denom, mu;
+ static XYZ n;
+
+ //Calculate the parameters for the plane
+ n.x = (pb.y - pa.y) * (pc.z - pa.z) - (pb.z - pa.z) * (pc.y - pa.y);
+ n.y = (pb.z - pa.z) * (pc.x - pa.x) - (pb.x - pa.x) * (pc.z - pa.z);
+ n.z = (pb.x - pa.x) * (pc.y - pa.y) - (pb.y - pa.y) * (pc.x - pa.x);
+ Normalise(&n);
+ d = - n.x * pa.x - n.y * pa.y - n.z * pa.z;
+
+ //Calculate the position on the line that intersects the plane
+ denom = n.x * (p2.x - p1.x) + n.y * (p2.y - p1.y) + n.z * (p2.z - p1.z);
+ if (fabs(denom) < 0.0000001) // Line and plane don't intersect
+ return 0;
+ mu = - (d + n.x * p1.x + n.y * p1.y + n.z * p1.z) / denom;
+ p->x = p1.x + mu * (p2.x - p1.x);
+ p->y = p1.y + mu * (p2.y - p1.y);
+ p->z = p1.z + mu * (p2.z - p1.z);
+ if (mu < 0 || mu > 1) // Intersection not along line segment
+ return 0;
+
+ if (!PointInTriangle( p, n, &pa, &pb, &pc)) {
+ return 0;
+ }
+
+ return 1;
+}
+
+float LineFacetd(XYZ p1, XYZ p2, XYZ pa, XYZ pb, XYZ pc, XYZ n, XYZ *p)
+{
+ static float d;
+ static float denom, mu;
+
+ //Calculate the parameters for the plane
+ d = - n.x * pa.x - n.y * pa.y - n.z * pa.z;
+
+ //Calculate the position on the line that intersects the plane
+ denom = n.x * (p2.x - p1.x) + n.y * (p2.y - p1.y) + n.z * (p2.z - p1.z);
+ if (fabs(denom) < 0.0000001) // Line and plane don't intersect
+ return 0;
+ mu = - (d + n.x * p1.x + n.y * p1.y + n.z * p1.z) / denom;
+ p->x = p1.x + mu * (p2.x - p1.x);
+ p->y = p1.y + mu * (p2.y - p1.y);
+ p->z = p1.z + mu * (p2.z - p1.z);
+ if (mu < 0 || mu > 1) // Intersection not along line segment
+ return 0;
+
+ if (!PointInTriangle( p, n, &pa, &pb, &pc)) {
+ return 0;
+ }
+ return 1;
+}
+
+float LineFacetd(XYZ *p1, XYZ *p2, XYZ *pa, XYZ *pb, XYZ *pc, XYZ *p)
+{
+ static float d;
+ static float denom, mu;
+ static XYZ n;
+
+ //Calculate the parameters for the plane
+ n.x = (pb->y - pa->y) * (pc->z - pa->z) - (pb->z - pa->z) * (pc->y - pa->y);
+ n.y = (pb->z - pa->z) * (pc->x - pa->x) - (pb->x - pa->x) * (pc->z - pa->z);
+ n.z = (pb->x - pa->x) * (pc->y - pa->y) - (pb->y - pa->y) * (pc->x - pa->x);
+ Normalise(&n);
+ d = - n.x * pa->x - n.y * pa->y - n.z * pa->z;
+
+
+ //Calculate the position on the line that intersects the plane
+ denom = n.x * (p2->x - p1->x) + n.y * (p2->y - p1->y) + n.z * (p2->z - p1->z);
+ if (fabs(denom) < 0.0000001) // Line and plane don't intersect
+ return 0;
+ mu = - (d + n.x * p1->x + n.y * p1->y + n.z * p1->z) / denom;
+ p->x = p1->x + mu * (p2->x - p1->x);
+ p->y = p1->y + mu * (p2->y - p1->y);
+ p->z = p1->z + mu * (p2->z - p1->z);
+ if (mu < 0 || mu > 1) // Intersection not along line segment
+ return 0;
+
+ if (!PointInTriangle( p, n, pa, pb, pc)) {
+ return 0;
+ }
+ return 1;
+}
+
+float LineFacetd(XYZ *p1, XYZ *p2, XYZ *pa, XYZ *pb, XYZ *pc, XYZ *n, XYZ *p)
+{
+ static float d;
+ static float denom, mu;
+
+ //Calculate the parameters for the plane
+ d = - n->x * pa->x - n->y * pa->y - n->z * pa->z;
+
+ //Calculate the position on the line that intersects the plane
+ denom = n->x * (p2->x - p1->x) + n->y * (p2->y - p1->y) + n->z * (p2->z - p1->z);
+ if (fabs(denom) < 0.0000001) // Line and plane don't intersect
+ return 0;
+ mu = - (d + n->x * p1->x + n->y * p1->y + n->z * p1->z) / denom;
+ p->x = p1->x + mu * (p2->x - p1->x);
+ p->y = p1->y + mu * (p2->y - p1->y);
+ p->z = p1->z + mu * (p2->z - p1->z);
+ if (mu < 0 || mu > 1) // Intersection not along line segment
+ return 0;
+
+ if (!PointInTriangle( p, *n, pa, pb, pc)) {
+ return 0;
+ }
+ return 1;
+}
+
+