rect.h

// Copyright (C) 2019 - DevSH Graphics Programming Sp. z O.O.
// This file is part of the "Nabla Engine" and was originally part of the "Irrlicht Engine"
// For conditions of distribution and use, see copyright notice in nabla.h
// See the original file in irrlicht source for authors

#ifndef __NBL_RECT_H_INCLUDED__
#define __NBL_RECT_H_INCLUDED__

#include "nbl/macros.h"
#include "nbl/core/decl/Types.h"
#include "dimension2d.h"
#include "position2d.h"

namespace nbl
{
namespace core
{

	//! Rectangle template.
	/** Mostly used by 2D GUI elements and for 2D drawing methods.
	It has 2 positions instead of position and dimension and a fast
	method for collision detection with other rectangles and points.

	Coordinates are (0,0) for top-left corner, and increasing to the right
	and to the bottom.
	*/
	template <class T>
	class rect// : public AllocationOverrideDefault
	{
	public:

		//! Default constructor creating empty rectangle at (0,0)
		rect() : UpperLeftCorner(0,0), LowerRightCorner(0,0) {}

		//! Constructor with two corners
		rect(T x, T y, T x2, T y2)
			: UpperLeftCorner(x,y), LowerRightCorner(x2,y2) {}

		//! Constructor with two corners
		rect(const position2d<T>& upperLeft, const position2d<T>& lowerRight)
			: UpperLeftCorner(upperLeft), LowerRightCorner(lowerRight) {}

		//! Constructor with upper left corner and dimension
		template <class U>
		rect(const position2d<T>& pos, const dimension2d<U>& size)
			: UpperLeftCorner(pos), LowerRightCorner(pos.X + size.Width, pos.Y + size.Height) {}

		//! move right by given numbers
		rect<T> operator+(const position2d<T>& pos) const
		{
			rect<T> ret(*this);
			return ret+=pos;
		}

		//! move right by given numbers
		rect<T>& operator+=(const position2d<T>& pos)
		{
			UpperLeftCorner += pos;
			LowerRightCorner += pos;
			return *this;
		}

		//! move left by given numbers
		rect<T> operator-(const position2d<T>& pos) const
		{
			rect<T> ret(*this);
			return ret-=pos;
		}

		//! move left by given numbers
		rect<T>& operator-=(const position2d<T>& pos)
		{
			UpperLeftCorner -= pos;
			LowerRightCorner -= pos;
			return *this;
		}

		//! equality operator
		bool operator==(const rect<T>& other) const
		{
			return (UpperLeftCorner == other.UpperLeftCorner &&
				LowerRightCorner == other.LowerRightCorner);
		}

		//! inequality operator
		bool operator!=(const rect<T>& other) const
		{
			return (UpperLeftCorner != other.UpperLeftCorner ||
				LowerRightCorner != other.LowerRightCorner);
		}

		//! compares size of rectangles
		bool operator<(const rect<T>& other) const
		{
			return getArea() < other.getArea();
		}

		//! Returns size of rectangle
		T getArea() const
		{
			return getWidth() * getHeight();
		}

		//! Returns if a 2d point is within this rectangle.
		/** \param pos Position to test if it lies within this rectangle.
		\return True if the position is within the rectangle, false if not. */
		bool isPointInside(const position2d<T>& pos) const
		{
			return (UpperLeftCorner.X <= pos.X &&
				UpperLeftCorner.Y <= pos.Y &&
				LowerRightCorner.X >= pos.X &&
				LowerRightCorner.Y >= pos.Y);
		}

		//! Check if the rectangle collides with another rectangle.
		/** \param other Rectangle to test collision with
		\return True if the rectangles collide. */
		bool isRectCollided(const rect<T>& other) const
		{
			return (LowerRightCorner.Y > other.UpperLeftCorner.Y &&
				UpperLeftCorner.Y < other.LowerRightCorner.Y &&
				LowerRightCorner.X > other.UpperLeftCorner.X &&
				UpperLeftCorner.X < other.LowerRightCorner.X);
		}

		//! Clips this rectangle with another one.
		/** \param other Rectangle to clip with */
		void clipAgainst(const rect<T>& other)
		{
			if (other.LowerRightCorner.X < LowerRightCorner.X)
				LowerRightCorner.X = other.LowerRightCorner.X;
			if (other.LowerRightCorner.Y < LowerRightCorner.Y)
				LowerRightCorner.Y = other.LowerRightCorner.Y;

			if (other.UpperLeftCorner.X > UpperLeftCorner.X)
				UpperLeftCorner.X = other.UpperLeftCorner.X;
			if (other.UpperLeftCorner.Y > UpperLeftCorner.Y)
				UpperLeftCorner.Y = other.UpperLeftCorner.Y;

			// correct possible invalid rect resulting from clipping
			if (UpperLeftCorner.Y > LowerRightCorner.Y)
				UpperLeftCorner.Y = LowerRightCorner.Y;
			if (UpperLeftCorner.X > LowerRightCorner.X)
				UpperLeftCorner.X = LowerRightCorner.X;
		}

		//! Moves this rectangle to fit inside another one.
		/** \return True on success, false if not possible */
		bool constrainTo(const rect<T>& other)
		{
			if (other.getWidth() < getWidth() || other.getHeight() < getHeight())
				return false;

			T diff = other.LowerRightCorner.X - LowerRightCorner.X;
			if (diff < 0)
			{
				LowerRightCorner.X += diff;
				UpperLeftCorner.X  += diff;
			}

			diff = other.LowerRightCorner.Y - LowerRightCorner.Y;
			if (diff < 0)
			{
				LowerRightCorner.Y += diff;
				UpperLeftCorner.Y  += diff;
			}

			diff = UpperLeftCorner.X - other.UpperLeftCorner.X;
			if (diff < 0)
			{
				UpperLeftCorner.X  -= diff;
				LowerRightCorner.X -= diff;
			}

			diff = UpperLeftCorner.Y - other.UpperLeftCorner.Y;
			if (diff < 0)
			{
				UpperLeftCorner.Y  -= diff;
				LowerRightCorner.Y -= diff;
			}

			return true;
		}

		//! Get width of rectangle.
		T getWidth() const
		{
			return LowerRightCorner.X - UpperLeftCorner.X;
		}

		//! Get height of rectangle.
		T getHeight() const
		{
			return LowerRightCorner.Y - UpperLeftCorner.Y;
		}

		//! If the lower right corner of the rect is smaller then the upper left, the points are swapped.
		void repair()
		{
			if (LowerRightCorner.X < UpperLeftCorner.X)
			{
				T t = LowerRightCorner.X;
				LowerRightCorner.X = UpperLeftCorner.X;
				UpperLeftCorner.X = t;
			}

			if (LowerRightCorner.Y < UpperLeftCorner.Y)
			{
				T t = LowerRightCorner.Y;
				LowerRightCorner.Y = UpperLeftCorner.Y;
				UpperLeftCorner.Y = t;
			}
		}

		//! Returns if the rect is valid to draw.
		/** It would be invalid if the UpperLeftCorner is lower or more
		right than the LowerRightCorner. */
		bool isValid() const
		{
			return ((LowerRightCorner.X >= UpperLeftCorner.X) &&
				(LowerRightCorner.Y >= UpperLeftCorner.Y));
		}

		//! Get the center of the rectangle
		position2d<T> getCenter() const
		{
			return position2d<T>(
					(UpperLeftCorner.X + LowerRightCorner.X) / 2,
					(UpperLeftCorner.Y + LowerRightCorner.Y) / 2);
		}

		//! Get the dimensions of the rectangle
		dimension2d<T> getSize() const
		{
			return dimension2d<T>(getWidth(), getHeight());
		}


		//! Adds a point to the rectangle
		/** Causes the rectangle to grow bigger if point is outside of
		the box
		\param p Point to add to the box. */
		void addInternalPoint(const position2d<T>& p)
		{
			addInternalPoint(p.X, p.Y);
		}

		//! Adds a point to the bounding rectangle
		/** Causes the rectangle to grow bigger if point is outside of
		the box
		\param x X-Coordinate of the point to add to this box.
		\param y Y-Coordinate of the point to add to this box. */
		void addInternalPoint(T x, T y)
		{
			if (x>LowerRightCorner.X)
				LowerRightCorner.X = x;
			if (y>LowerRightCorner.Y)
				LowerRightCorner.Y = y;

			if (x<UpperLeftCorner.X)
				UpperLeftCorner.X = x;
			if (y<UpperLeftCorner.Y)
				UpperLeftCorner.Y = y;
		}

		//! Upper left corner
		position2d<T> UpperLeftCorner;
		//! Lower right corner
		position2d<T> LowerRightCorner;
	};

	//! Rectangle with float values
	typedef rect<float> rectf;
	//! Rectangle with int values
	typedef rect<int32_t> recti;

} // end namespace core
} // end namespace nbl

#endif