Update.

[flatland.git] / polygon.cc

diff --git a/polygon.cc b/polygon.cc
index 69b125e..bfa95f8 100644 (file)
--- a/polygon.cc
+++ b/polygon.cc
@@ -356,7 +356,9 @@ void Polygon::apply_force(scalar_t dt, scalar_t x, scalar_t y, scalar_t fx, scal
   _dtheta -= prod_vect(x - _center_x, y - _center_y, fx, fy) / (_mass * _moment_of_inertia) * dt;
 }
 
-void Polygon::apply_border_forces(scalar_t dt, scalar_t xmax, scalar_t ymax) {
+void Polygon::apply_border_forces(scalar_t dt,
+                                  scalar_t xmin, scalar_t ymin,
+                                  scalar_t xmax, scalar_t ymax) {
   for(int v = 0; v < _nb_vertices; v++) {
     int vp = (v+1)%_nb_vertices;
     for(int d = 0; d < _nb_dots[v]; d++) {
@@ -364,9 +366,9 @@ void Polygon::apply_border_forces(scalar_t dt, scalar_t xmax, scalar_t ymax) {
       scalar_t x = _x[v] * (1 - s) + _x[vp] * s;
       scalar_t y = _y[v] * (1 - s) + _y[vp] * s;
       scalar_t vx = 0, vy = 0;
-      if(x < 0) vx = x;
+      if(x < xmin) vx = xmin - x;
       else if(x > xmax) vx = x - xmax;
-      if(y < 0) vy = y;
+      if(y < ymin) vy = ymin - y;
       else if(y > ymax) vy = y - ymax;
       apply_force(dt, x, y, - dl * vx * repulsion_constant, - dl * vy * repulsion_constant);
     }
@@ -390,9 +392,10 @@ void Polygon::apply_collision_forces(scalar_t dt, int n_polygon, Polygon *p) {
       distance[d] = FLT_MAX;
     }
 
-    // First, we tag the dots located inside the polygon p
+    // First, we tag the dots located inside the polygon p by looping
+    // through the _nb_vertices - 2 triangles from the decomposition
 
-    for(int t = 0; t < p->_nb_vertices-2; t++) {
+    for(int t = 0; t < p->_nb_vertices - 2; t++) {
       scalar_t min = 0, max = 1;
       scalar_t xa = p->_x[p->_triangles[t].a], ya = p->_y[p->_triangles[t].a];
       scalar_t xb = p->_x[p->_triangles[t].b], yb = p->_y[p->_triangles[t].b];
@@ -514,6 +517,14 @@ void Polygon::apply_collision_forces(scalar_t dt, int n_polygon, Polygon *p) {
 
 }
 
+bool Polygon::collide_with_borders(scalar_t xmin, scalar_t ymin,
+                                   scalar_t xmax, scalar_t ymax) {
+  for(int n = 0; n < _nb_vertices; n++) {
+    if(_x[n] <= xmin || _x[n] >= xmax || _y[n] <= ymin || _y[n] >= ymax) return true;
+  }
+  return false;
+}
+
 bool Polygon::collide(Polygon *p) {
   for(int n = 0; n < _nb_vertices; n++) {
     int np = (n+1)%_nb_vertices;