BansheeEngine/BansheeEditor/Include/BsHandleSliderLine.h

#pragma once

#include "BsEditorPrerequisites.h"
#include "BsHandleSlider.h"
#include "BsCapsule.h"
#include "BsSphere.h"

namespace BansheeEngine
{
	/**
	 * @brief	Handle slider that returns a delta value as you drag the pointer
	 *			along a line. For intersection purposes the line is internally 
	 *			by a capsule and a sphere at its cap (assuming this will be used 
	 *			for arrow-like handles).
	 */
	class BS_ED_EXPORT HandleSliderLine : public HandleSlider
	{
	public:
		/**
		 * @brief	Constructs a new line slider.
		 *
		 * @param	direction	Direction of the line.
		 * @param	length		Length of the slider (i.e. the line).
		 * @param	fixedScale	If true the handle slider will always try to maintain the same visible
		 *						area in the viewport regardless of distance from camera.
		 * @param	layer		Layer that allows filtering of which sliders are interacted with from a specific camera.
		 */
		HandleSliderLine(const Vector3& direction, float length, bool fixedScale, UINT64 layer);
		~HandleSliderLine();

		/**
		 * @copydoc	HandleSlider::intersects
		 */
		bool intersects(const Ray& ray, float& t) const override;

		/**
		 * @copydoc	HandleSlider::handleInput
		 */
		void handleInput(const CameraPtr& camera, const Vector2I& inputDelta) override;

		/**
		 * @brief	Returns a delta value that is the result of dragging/sliding the pointer 
		 *			along the line. This changes every frame and will be zero unless the slider is active.
		 */
		float getDelta() const { return mDelta; }

	protected:
		/**
		 * @copydoc	HandleSlider::activate
		 */
		void activate(const CameraPtr& camera, const Vector2I& pointerPos) override { mStartPosition = getPosition(); }

		/**
		 * @copydoc	HandleSlider::reset
		 */
		void reset() override { mDelta = 0.0f; }

		static const float CAPSULE_RADIUS;
		static const float SPHERE_RADIUS;

		Vector3 mDirection;
		float mLength;

		float mDelta;
		Vector3 mStartPosition;

		Capsule mCapsuleCollider;
		Sphere mSphereCollider;
	};
}