GODOT IS OPEN SOURCE

1 files changed, 168 insertions, 0 deletions

diff --git a/core/math/triangulate.cpp b/core/math/triangulate.cpp
new file mode 100644
index 0000000000..4a870def4b
--- /dev/null
+++ b/core/math/triangulate.cpp
@@ -0,0 +1,168 @@
+/*************************************************************************/
+/*  triangulate.cpp                                                      */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                    http://www.godotengine.org                         */
+/*************************************************************************/
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                 */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+#include "triangulate.h"
+
+float Triangulate::get_area(const Vector<Vector2> &contour)
+{
+
+  int n = contour.size();
+  const Vector2 *c=&contour[0];
+
+  float A=0.0f;
+
+  for(int p=n-1,q=0; q<n; p=q++)
+  {
+    A+= c[p].cross(c[q]);
+  }
+  return A*0.5f;
+}
+
+   /*
+     is_inside_triangle decides if a point P is Inside of the triangle
+     defined by A, B, C.
+   */
+
+bool Triangulate::is_inside_triangle(float Ax, float Ay,
+		      float Bx, float By,
+		      float Cx, float Cy,
+		      float Px, float Py)
+
+{
+  float ax, ay, bx, by, cx, cy, apx, apy, bpx, bpy, cpx, cpy;
+  float cCROSSap, bCROSScp, aCROSSbp;
+
+  ax = Cx - Bx;  ay = Cy - By;
+  bx = Ax - Cx;  by = Ay - Cy;
+  cx = Bx - Ax;  cy = By - Ay;
+  apx= Px - Ax;  apy= Py - Ay;
+  bpx= Px - Bx;  bpy= Py - By;
+  cpx= Px - Cx;  cpy= Py - Cy;
+
+  aCROSSbp = ax*bpy - ay*bpx;
+  cCROSSap = cx*apy - cy*apx;
+  bCROSScp = bx*cpy - by*cpx;
+
+  return ((aCROSSbp >= 0.0f) && (bCROSScp >= 0.0f) && (cCROSSap >= 0.0f));
+};
+
+bool Triangulate::snip(const Vector<Vector2> &p_contour,int u,int v,int w,int n,int *V)
+{
+  int p;
+  float Ax, Ay, Bx, By, Cx, Cy, Px, Py;
+  const Vector2 *contour=&p_contour[0];
+
+  Ax = contour[V[u]].x;
+  Ay = contour[V[u]].y;
+
+  Bx = contour[V[v]].x;
+  By = contour[V[v]].y;
+
+  Cx = contour[V[w]].x;
+  Cy = contour[V[w]].y;
+
+  if ( CMP_EPSILON > (((Bx-Ax)*(Cy-Ay)) - ((By-Ay)*(Cx-Ax))) ) return false;
+
+  for (p=0;p<n;p++)
+  {
+    if( (p == u) || (p == v) || (p == w) ) continue;
+    Px = contour[V[p]].x;
+    Py = contour[V[p]].y;
+    if (is_inside_triangle(Ax,Ay,Bx,By,Cx,Cy,Px,Py)) return false;
+  }
+
+  return true;
+}
+
+bool Triangulate::triangulate(const Vector<Vector2> &contour,Vector<int> &result)
+{
+  /* allocate and initialize list of Vertices in polygon */
+
+  int n = contour.size();
+  if ( n < 3 ) return false;
+
+
+
+  int *V = (int*)alloca(sizeof(int)*n);
+
+  /* we want a counter-clockwise polygon in V */
+
+  if ( 0.0f < get_area(contour) )
+    for (int v=0; v<n; v++) V[v] = v;
+  else
+    for(int v=0; v<n; v++) V[v] = (n-1)-v;
+
+  int nv = n;
+
+  /*  remove nv-2 Vertices, creating 1 triangle every time */
+  int count = 2*nv;   /* error detection */
+
+  for(int m=0, v=nv-1; nv>2; )
+  {
+    /* if we loop, it is probably a non-simple polygon */
+    if (0 >= (count--))
+    {
+      //** Triangulate: ERROR - probable bad polygon!
+      return false;
+    }
+
+    /* three consecutive vertices in current polygon, <u,v,w> */
+    int u = v  ; if (nv <= u) u = 0;     /* previous */
+    v = u+1; if (nv <= v) v = 0;     /* new v    */
+    int w = v+1; if (nv <= w) w = 0;     /* next     */
+
+    if ( snip(contour,u,v,w,nv,V) )
+    {
+      int a,b,c,s,t;
+
+      /* true names of the vertices */
+      a = V[u]; b = V[v]; c = V[w];
+
+      /* output Triangle */
+      /*
+      result.push_back( contour[a] );
+      result.push_back( contour[b] );
+      result.push_back( contour[c] );
+*/
+
+      result.push_back( a );
+      result.push_back( b );
+      result.push_back( c );
+
+      m++;
+
+      /* remove v from remaining polygon */
+      for(s=v,t=v+1;t<nv;s++,t++) V[s] = V[t]; nv--;
+
+      /* resest error detection counter */
+      count = 2*nv;
+    }
+  }
+
+  return true;
+}