Class Camera3D_Orbit

utilities/olcUTIL_Hardware3D.h:1302–1387

	};

	class Camera3D_Orbit : public Camera3D
	{
	public:
		inline void Pan(const olc::vf3d& vScreenMoved)
		{
			vecTarget -= vScreenMoved * fCameraRadius;
			vecPosition -= vScreenMoved * fCameraRadius;
		}

		inline void Zoom(const float fZoomDelta)
		{
			fCameraRadius *= fZoomDelta;
		}


		inline void Spin(const olc::vf2d& vScreenMoved)
		{			
			vSpin = 2.0f * (vScreenMoved / vScreenSize) * fProjection_AspectRatio;
		}


		void Update() override
		{
			// Calculate where camera is given, target, position and up	as usual		
			vecViewForward = -(GetTarget() - GetPosition()).norm();
			vecViewUp = (vecAxisUp - (vecAxisUp.dot(vecViewForward) * vecViewForward)).norm();
			vecViewRight = vecViewUp.cross(vecViewForward);

			// Turn screen space gesture into projected 3D action...
			float fDirectionOfRotation = -std::atan2(vSpin.y, vSpin.x);
			float fMagnitudeOfRotation = vSpin.mag();
			// Create an axis of rotation through the camera, that corresponds to gesture
			// Consider this a plane through the camera where mouse movement defines orthogonality
			olc::vf3d vRotation = vecViewUp * std::sin(fDirectionOfRotation) - vecViewRight * std::cos(fDirectionOfRotation);
			// Which gives us a 3rd "new" axis to complete lhr
			olc::vf3d vNewAxis = vecViewForward.cross(vRotation);

			// See https://github.com/processing/p5.js/blob/v1.11.3/src/webgl/p5.Camera.js#L3854 for
			// inspiration, but modified here in OLC land. Here we generate the Up vector around the 
			// new axis to implement tilt, i.e. rotate the Up
			float s = std::sin(fMagnitudeOfRotation);
			float c = std::cos(fMagnitudeOfRotation);
			float dotFront = vecAxisUp.dot(vecViewForward);
			float dotSide = vecAxisUp.dot(vRotation);			
			float ux = dotFront * c + dotSide * s;
			float uy = -dotFront * s + dotSide * c;
			float uz = vecAxisUp.dot(vNewAxis);
						// Forward          + Side (Tilt Axis) + Tilted Up
			vecViewUp = ux * vecViewForward + uy * vRotation   + uz * vNewAxis;

			// Panning, Recall Forward is normed and 90 degrees to Rotation
			vRotation *= -s;
			vecViewForward *= c;
			vecViewForward += vRotation;

			// Offset back to user's expectation of distance away from target
			vecViewForward *= fCameraRadius;
			vecPosition = vecViewForward + vecTarget;