Add steer parameter to CSceneNodeAnimatorFollowSpline which allows rotating node toward direction of movement.

Thanks @ Bate for the patch (patch #175 with minor changes).

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6234 dfc29bdd-3216-0410-991c-e03cc46cb475

changes.txt

@@ -1,5 +1,7 @@
 --------------------------
 Changes in 1.9 (not yet released)
+- Add steer parameter to CSceneNodeAnimatorFollowSpline which allows rotating node toward direction of movement. 
+  Thanks @ Bate for the patch (patch #175)
 - Add a workaround for XWarpPointer bug that causes mouse to jump when users have set a Coordinate Transformation Matrix for their mouse on X11.
   This was mentioned in bug #450 by vikaig.
   The fix needs compiling with _IRR_LINUX_X11_XINPUT2_ enabled (so far disabled by default)

include/ISceneManager.h

@@ -1261,7 +1261,7 @@ namespace scene
 		See IReferenceCounted::drop() for more information. */
 		virtual ISceneNodeAnimator* createFollowSplineAnimator(s32 startTime,
 			const core::array< core::vector3df >& points,
-			f32 speed = 1.0f, f32 tightness = 0.5f, bool loop=true, bool pingpong=false) = 0;
+			f32 speed = 1.0f, f32 tightness = 0.5f, bool loop=true, bool pingpong=false, bool steer=false) = 0;
 
 		//! Creates a simple ITriangleSelector, based on a mesh.
 		/** Triangle selectors

source/Irrlicht/CSceneManager.cpp

@@ -1872,10 +1872,10 @@ ISceneNodeAnimatorCollisionResponse* CSceneManager::createCollisionResponseAnima
 //! Creates a follow spline animator.
 ISceneNodeAnimator* CSceneManager::createFollowSplineAnimator(s32 startTime,
 	const core::array< core::vector3df >& points,
-	f32 speed, f32 tightness, bool loop, bool pingpong)
+	f32 speed, f32 tightness, bool loop, bool pingpong, bool steer)
 {
 	ISceneNodeAnimator* a = new CSceneNodeAnimatorFollowSpline(startTime, points,
-		speed, tightness, loop, pingpong);
+		speed, tightness, loop, pingpong, steer);
 	return a;
 }
 

source/Irrlicht/CSceneManager.h

@@ -341,7 +341,7 @@ namespace scene
 		//! Creates a follow spline animator.
 		virtual ISceneNodeAnimator* createFollowSplineAnimator(s32 startTime,
 			const core::array< core::vector3df >& points,
-			f32 speed, f32 tightness, bool loop, bool pingpong) _IRR_OVERRIDE_;
+			f32 speed, f32 tightness, bool loop, bool pingpong, bool steer) _IRR_OVERRIDE_;
 
 
 		//! Creates a simple ITriangleSelector, based on a mesh.

source/Irrlicht/CSceneNodeAnimatorFollowSpline.cpp

@@ -13,15 +13,17 @@ namespace scene
 //! constructor
 CSceneNodeAnimatorFollowSpline::CSceneNodeAnimatorFollowSpline(u32 time,
 	const core::array<core::vector3df>& points, f32 speed,
-	f32 tightness, bool loop, bool pingpong)
+	f32 tightness, bool loop, bool pingpong, bool steer)
 : ISceneNodeAnimatorFinishing(0), Points(points), Speed(speed), Tightness(tightness)
-, Loop(loop), PingPong(pingpong)
+, Loop(loop), PingPong(pingpong), Steer(steer)
 {
 	#ifdef _DEBUG
 	setDebugName("CSceneNodeAnimatorFollowSpline");
 	#endif
 
 	StartTime = time;
+	//if (points.size() != 0)
+	//	LastPos = points[0];
 }
 
 
@@ -86,7 +88,17 @@ void CSceneNodeAnimatorFollowSpline::animateNode(ISceneNode* node, u32 timeMs)
 	const core::vector3df t2 = ( p3 - p1 ) * Tightness;
 
 	// interpolated point
-	node->setPosition(p1 * h1 + p2 * h2 + t1 * h3 + t2 * h4);
+	const core::vector3df lastPos(node->getPosition());
+	const core::vector3df pos(p1 * h1 + p2 * h2 + t1 * h3 + t2 * h4);
+	node->setPosition(pos);
+
+	// steering (rotate in direction of movement)
+	if (Steer && !pos.equals(lastPos)) // equality check fixes glitches due to very high frame rates
+	{
+		const core::vector3df toTarget(pos - lastPos);
+		const core::vector3df requiredRotation = toTarget.getHorizontalAngle();
+		node->setRotation(requiredRotation);
+	}
 }
 
 
@@ -99,6 +111,7 @@ void CSceneNodeAnimatorFollowSpline::serializeAttributes(io::IAttributes* out, i
 	out->addFloat("Tightness", Tightness);
 	out->addBool("Loop", Loop);
 	out->addBool("PingPong", PingPong);
+	out->addBool("Steer", Steer);
 
 	u32 count = Points.size();
 
@@ -124,10 +137,11 @@ void CSceneNodeAnimatorFollowSpline::deserializeAttributes(io::IAttributes* in,
 {
 	ISceneNodeAnimatorFinishing::deserializeAttributes(in, options);
 
-	Speed = in->getAttributeAsFloat("Speed");
-	Tightness = in->getAttributeAsFloat("Tightness");
-	Loop = in->getAttributeAsBool("Loop");
-	PingPong = in->getAttributeAsBool("PingPong");
+	Speed = in->getAttributeAsFloat("Speed", Speed);
+	Tightness = in->getAttributeAsFloat("Tightness", Tightness);
+	Loop = in->getAttributeAsBool("Loop", Loop);
+	PingPong = in->getAttributeAsBool("PingPong", PingPong);
+	Steer = in->getAttributeAsBool("Steer", Steer);
 	Points.clear();
 
 	for(u32 i=1; true; ++i)

source/Irrlicht/CSceneNodeAnimatorFollowSpline.h

@@ -22,7 +22,7 @@ namespace scene
 		//! constructor
 		CSceneNodeAnimatorFollowSpline(u32 startTime,
 			const core::array< core::vector3df >& points,
-			f32 speed = 1.0f, f32 tightness = 0.5f, bool loop=true, bool pingpong=false);
+			f32 speed = 1.0f, f32 tightness = 0.5f, bool loop=true, bool pingpong=false, bool steer=false);
 
 		//! animates a scene node
 		virtual void animateNode(ISceneNode* node, u32 timeMs) _IRR_OVERRIDE_;
@@ -52,6 +52,7 @@ namespace scene
 		f32 Tightness;
 		bool Loop;
 		bool PingPong;
+		bool Steer;	// rotate depending on current movement
 	};