BGE physics: When colliding, report first contact point to Python

This patch adds two parameters to the functions in the
collisionCallbacks list. The callback function should thus be like
this:

```
def on_colliding(other, point, normal):
    print("Colliding with %s at %s with normal %s" % (other, point, normal))

game_ob.collisionCallbacks.append(on_colliding)
```

The `point` parameter will contain the collision point in world
coordinates on the current object, and the `normal` contains the
surface normal at the collision point.

The callback functions are checked for the number of arguments
`co_argcount`. The new `point` and `normal` arguments are only passed
when `co_argcount > 1` or when `co_argcount` cannot be determined.

Reviewers: brita_, campbellbarton

Subscribers: sergey, sybren, agoose77

Projects: #game_physics

Differential Revision: https://developer.blender.org/D926

1 files changed, 23 insertions, 1 deletions

diff --git a/source/gameengine/Ketsji/KX_TouchEventManager.h b/source/gameengine/Ketsji/KX_TouchEventManager.h
index bd4903c1545..d9c6fdad307 100644
--- a/source/gameengine/Ketsji/KX_TouchEventManager.h
+++ b/source/gameengine/Ketsji/KX_TouchEventManager.h
@@ -45,7 +45,29 @@ class PHY_IPhysicsEnvironment;
 
 class KX_TouchEventManager : public SCA_EventManager
 {
-	typedef std::pair<PHY_IPhysicsController*, PHY_IPhysicsController*> NewCollision;
+	/**
+	 * Contains two colliding objects and the first contact point.
+	 */
+	class NewCollision {
+	public:
+		PHY_IPhysicsController *first;
+		PHY_IPhysicsController *second;
+		PHY_CollData *colldata;
+
+		/**
+	     * Creates a copy of the given PHY_CollData; freeing that copy should be done by the owner of
+	     * the NewCollision object.
+	     *
+	     * This allows us to efficiently store NewCollision objects in a std::set without creating more
+	     * copies of colldata, as the NewCollision copy constructor reuses the pointer and doesn't clone
+	     * it again. */
+		NewCollision(PHY_IPhysicsController *first,
+		             PHY_IPhysicsController *second,
+		             const PHY_CollData *colldata);
+		NewCollision(const NewCollision &to_copy);
+		bool operator<(const NewCollision &other) const;
+	};
+
 	PHY_IPhysicsEnvironment*	m_physEnv;
 	
 	std::set<NewCollision> m_newCollisions;