From 9284cd8bb4fe83fad551a6b51fc1f8c9c95b6591 Mon Sep 17 00:00:00 2001
From: Francois Fleuret <francois.fleuret@idiap.ch>
Date: Tue, 8 Jan 2019 18:13:30 +0100
Subject: [PATCH] Added gravity.

---
 main.cc     | 1 +
 universe.cc | 8 ++++++++
 universe.h  | 1 +
 3 files changed, 10 insertions(+)

diff --git a/main.cc b/main.cc
index 974cbea..6f423a9 100644
--- a/main.cc
+++ b/main.cc
@@ -281,6 +281,7 @@ int main(int argc, char **argv) {
         for(int k = 0; k < nb_it; k++) {
           manipulator.update(dt, &universe);
           task->update(dt, &universe, &manipulator);
+          universe.apply_gravity(dt, 0.0, 2.0);
           changed |= universe.update(dt);
         }
 
diff --git a/universe.cc b/universe.cc
index 4a2e4f9..8dec7f5 100644
--- a/universe.cc
+++ b/universe.cc
@@ -163,6 +163,14 @@ void Universe::draw(Canvas *canvas) {
   }
 }
 
+void Universe::apply_gravity(scalar_t dt, scalar_t fx, scalar_t fy) {
+  for(int n = 0; n < _nb_polygons; n++)
+    if(_polygons[n])
+      _polygons[n]->apply_force(dt,
+                                _polygons[n]->_center_x, _polygons[n]->_center_y,
+                                fx, fy);
+}
+
 void Universe::apply_collision_forces(scalar_t dt) {
   const int nb_axis = 2;
   int nb_collision[_nb_polygons * _nb_polygons];
diff --git a/universe.h b/universe.h
index a48a3ba..520a123 100644
--- a/universe.h
+++ b/universe.h
@@ -39,6 +39,7 @@ public:
   // Compute collisions between projections of the polygons on a few
   // axis to speed up the computation
   void compute_pseudo_collisions(int nb_axis, int *nb_colliding_axis);
+  void apply_gravity(scalar_t dt, scalar_t fx, scalar_t fy);
   void apply_collision_forces(scalar_t dt);
   bool update(scalar_t dt);
 
-- 
2.39.5