Rope: Add Pull functions

src/object/C4Rope.cpp

@@ -328,7 +328,7 @@ bool C4RopeElement::SetForceRedirectionByLookAround(const C4Rope* rope, int ox,
 C4Rope::C4Rope(C4PropList* Prototype, C4Object* first_obj, C4Object* second_obj, C4Real segment_length, C4DefGraphics* graphics):
 	C4PropListNumbered(Prototype), Width(5.0f), Graphics(graphics), SegmentCount(itofix(ObjectDistance(first_obj, second_obj))/segment_length),
 	l(segment_length), k(Fix1*3), mu(Fix1*3), eta(Fix1*3), NumIterations(10),
-	FrontAutoSegmentation(Fix0), BackAutoSegmentation(Fix0)
+	FrontAutoSegmentation(Fix0), BackAutoSegmentation(Fix0), FrontPull(Fix0), BackPull(Fix0)
 {
 	if(!PathFree(first_obj->GetX(), first_obj->GetY(), second_obj->GetX(), second_obj->GetY()))
 		throw C4RopeError("Path between objects is blocked");
@@ -577,10 +577,29 @@ void C4Rope::Execute()
 		DoAutoSegmentation(Front, Front->Next, FrontAutoSegmentation);
 		DoAutoSegmentation(Back, Back->Prev, BackAutoSegmentation);
 
-		// Compute forces
+		// Compute inter-rope forces
 		for(C4RopeElement* cur = Front; cur->Next != NULL; cur = cur->Next)
 			Solve(cur, cur->Next);
 
+		// Front/BackPull
+		if(FrontPull != Fix0)
+		{
+			const C4Real dx = Front->Next->GetX() - Front->GetX();
+			const C4Real dy = Front->Next->GetY() - Front->GetY();
+			const C4Real d = ftofix(sqrt(fixtof(dx*dx+dy*dy)));
+			if(d != Fix0)
+				Front->Next->AddForce(-dx/d * FrontPull, -dy/d * FrontPull);
+		}
+
+		if(BackPull != Fix0)
+		{
+			const C4Real dx = Back->Prev->GetX() - Back->GetX();
+			const C4Real dy = Back->Prev->GetY() - Back->GetY();
+			const C4Real d = ftofix(sqrt(fixtof(dx*dx+dy*dy)));
+			if(d != Fix0)
+				Back->Prev->AddForce(-dx/d * BackPull, -dy/d * BackPull);
+		}
+
 		// Apply forces
 		for(C4RopeElement* cur = Front; cur != NULL; cur = cur->Next)
 			cur->Execute(this, dt);

src/object/C4Rope.h

@@ -91,6 +91,9 @@ public:
 	bool GetBackFixed() const { return Back->Fixed; }
 	void SetFrontFixed(bool fixed) { Front->Fixed = fixed; }
 	void SetBackFixed(bool fixed) { Back->Fixed = fixed; }
+
+	void PullFront(C4Real f) { FrontPull = f; }
+	void PullBack(C4Real f) { BackPull = f; }
 private:
 	C4Real GetL(const C4RopeElement* prev, const C4RopeElement* next) const;
 
@@ -116,6 +119,9 @@ private:
 
 	C4Real FrontAutoSegmentation;
 	C4Real BackAutoSegmentation;
+
+	C4Real FrontPull;
+	C4Real BackPull;
 };
 
 class C4RopeAul: public C4AulScript

src/object/C4RopeScript.cpp

@@ -71,6 +71,18 @@ static C4Void FnSetBackFixed(C4AulContext* Context, bool fixed)
 	return C4Void();
 }
 
+static C4Void FnPullFront(C4AulContext* Context, int force)
+{
+	static_cast<C4Rope*>(Context->Def)->PullFront(itofix(force));
+	return C4Void();
+}
+
+static C4Void FnPullBack(C4AulContext* Context, int force)
+{
+	static_cast<C4Rope*>(Context->Def)->PullBack(itofix(force));
+	return C4Void();
+}
+
 C4RopeAul::C4RopeAul():
 	RopeDef(NULL)
 {
@@ -98,5 +110,7 @@ void C4RopeAul::InitFunctionMap(C4AulScriptEngine* pEngine)
 	::AddFunc(this, "SetBackAutoSegmentation", FnSetBackAutoSegmentation);
 	::AddFunc(this, "SetFrontFixed", FnSetFrontFixed);
 	::AddFunc(this, "SetBackFixed", FnSetBackFixed);
+	::AddFunc(this, "PullFront", FnPullFront);
+	::AddFunc(this, "PullBack", FnPullBack);
 	RopeDef->Freeze();
 }