Implement RotateFree::transform()

libs/math/Ray.h

@@ -251,4 +251,30 @@ class Ray
 
 		return POINT; // I is in T
 	}
+
+	/**
+	 * Tries to find the intersection point of this Ray with the sphere given by its
+	 * origin and radius. The intersection will be written to the given Vector3.
+	 * Returns false if the Ray misses the sphere, in which case the intersection will
+	 * be returned as the Ray's nearest point to the sphere.
+	 * Taken from GtkRadiant's sphere_intersect_ray() function. 
+	 */
+	bool intersectSphere(const Vector3& sphereOrigin, double radius, Vector3& intersection) const
+	{
+		intersection = sphereOrigin - origin;
+
+		const double a = intersection.dot(direction);
+		const double d = radius * radius - (intersection.dot(intersection) - a * a);
+
+		if (d > 0)
+		{
+			intersection = origin + direction * (a - sqrt(d));
+			return true;
+		}
+		else
+		{
+			intersection = origin + direction*a;
+			return false;
+		}
+	}
 };

radiant/selection/manipulators/ManipulatorComponents.cpp

@@ -38,23 +38,48 @@ Vector3 ManipulatorComponentBase::getPlaneProjectedPoint(const Matrix4& pivot2wo
 	return device2pivot.transform(point).getProjected();
 }
 
+Vector3 ManipulatorComponentBase::getSphereIntersection(const Matrix4& pivot2world, const VolumeTest& view, const Vector2& devicePoint)
+{
+	// Construct a ray to intersect with a defined sphere
+
+	// The device coords x,y generated by the mouse click already defines a ray in 3D space,
+	// we just need to pick a z coordinate for start and end. For simplicity we use z=-1 and z=+1
+	// which resolves to the near and far plane in device space.
+	Vector4 deviceOrigin(devicePoint.x(), devicePoint.y(), -1, 1); // point on near plane
+	Vector4 deviceEnd(devicePoint.x(), devicePoint.y(), +1, 1); // point on far plane
+
+	// Run these points through the device2pivot matrix and construct the ray
+	Matrix4 device2pivot = constructDevice2Pivot(pivot2world, view);
+
+	Vector3 rayOrigin = device2pivot.transform(deviceOrigin).getProjected();
+	Vector3 rayDirection = (device2pivot.transform(deviceEnd).getProjected() - rayOrigin).getNormalised();
+
+	// Construct the ray and return the intersection or the Ray's nearest point to the sphere
+	Ray ray(rayOrigin, rayDirection);
+
+	Vector3 intersectionPoint;
+	ray.intersectSphere(Vector3(0, 0, 0), 64.0, intersectionPoint);
+
+	return intersectionPoint;
+}
+
 // ===============================================================================================
 
 void RotateFree::beginTransformation(const Matrix4& pivot2world, const VolumeTest& view, const Vector2& devicePoint)
 {
-    //point_on_sphere(_start, device2manip, x, y);
-    //_start.normalise();
+	_start = getSphereIntersection(pivot2world, view, devicePoint);
+    _start.normalise();
 }
 
 void RotateFree::transform(const Matrix4& pivot2world, const VolumeTest& view, const Vector2& devicePoint)
 {
- //   Vector3 current;
+	Vector3 current = getSphereIntersection(pivot2world, view, devicePoint);
+	current.normalise();
 
- //   point_on_sphere(current, device2manip, x, y);
- //   current.normalise();
+	// call the Rotatable with its transform method
+	Quaternion rotation = Quaternion::createForUnitVectors(_start, current);
 
-	//// call the Rotatable with its transform method
- //   _rotatable.rotate(Quaternion::createForUnitVectors(_start, current));
+	_rotatable.rotate(rotation);
 }
 
 // ===============================================================================================

radiant/selection/manipulators/ManipulatorComponents.h

@@ -30,6 +30,12 @@ class ManipulatorComponentBase :
 	 * located on the plane going through pivot space origin, orthogonal to the view direction
 	 */
 	Vector3 getPlaneProjectedPoint(const Matrix4& pivot2world, const VolumeTest& view, const Vector2& devicePoint);
+
+	/**
+	 * Returns the intersection point of the Ray defined by the given devicepoint with a sphere 
+	 * located at the pivot space origin. If the Ray misses the sphere, its nearest point will be returned.
+	 */
+	Vector3 getSphereIntersection(const Matrix4& pivot2world, const VolumeTest& view, const Vector2& devicePoint);
 };
 
 /* greebo: The following are specialised manipulatables that provide the methods as described in the ABC.
@@ -40,8 +46,9 @@ class ManipulatorComponentBase :
  */
 
 class RotateFree : 
-	public Manipulator::Component
+	public ManipulatorComponentBase
 {
+private:
 	Vector3 _start;
 	Rotatable& _rotatable;
 public: