kicad/pcbnew/router/direction.h

/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013  CERN
 * Author: Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
 * 
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.or/licenses/>.
 */

#ifndef __DIRECTION_H
#define __DIRECTION_H

#include <geometry/seg.h>
#include <geometry/shape_line_chain.h>

/**
 * Class DIRECTION_45.
 * Represents route directions & corner angles in a 45-degree metric.
 */

class DIRECTION_45
{
	
public:
	
	/**
	 * Enum Directions
	 * Represents available directions - there are 8 of them, as on a rectilinear map (north = up) +
	 * an extra undefined direction, reserved for traces that don't respect 45-degree routing regime.
	 */
	enum Directions {
		N = 0, 
		NE = 1, 
		E = 2, 
		SE = 3, 
		S = 4, 
		SW = 5, 
		W = 6, 
		NW = 7, 
		UNDEFINED = -1
	};

	/**
	 * Enum AngleType
	 * Represents kind of angle formed by vectors heading in two DIRECTION_45s. 
	 */
	enum AngleType {
		ANG_OBTUSE = 0x1,
		ANG_RIGHT = 0x2,
		ANG_ACUTE = 0x4,
		ANG_STRAIGHT = 0x8,
		ANG_HALF_FULL = 0x10,
		ANG_UNDEFINED = 0x20
	};

	DIRECTION_45(Directions aDir = UNDEFINED): m_dir(aDir) {};
	
	/**
	 * Constructor
	 * @param aVec vector, whose direction will be translated into a DIRECTION_45.
	 */
	DIRECTION_45(const VECTOR2I& aVec)
	{
		construct(aVec);
	}

	/**
	 * Constructor
	 * @param aSeg segment, whose direction will be translated into a DIRECTION_45.
	 */
	DIRECTION_45(const SEG& aSeg)
	{
		construct( aSeg.b - aSeg.a );
	}

	/**
	 * Function Format()
	 * Formats the direction in a human readable word.
	 * @return name of the direction
	 */
	const std::string Format() const
	{
		switch(m_dir)
		{
			case N : return "north";
			case NE : return "north-east";
			case E : return "east";
			case SE : return "south-east";
			case S : return "south";
			case SW : return "south-west";
			case W : return "west";
			case NW : return "north-west";
			case UNDEFINED : return "undefined";
			default: return "<Error>";
		}
	}
	
	/**
	 * Function Opposite()
	 * Returns a direction opposite (180 degree) to (this)
	 * @return opposite direction
	 */
	DIRECTION_45 Opposite() const
	{
		if(m_dir == UNDEFINED)
			return UNDEFINED;
		const Directions OppositeMap[] = { S, SW, W, NW, N, NE, E, SE }	;
		return OppositeMap[m_dir];
	}

	/**
	 * Function Angle()
	 * Returns the type of angle between directions (this) and aOther.
	 * @param aOther direction to compare angle with
	 */
	AngleType Angle(const DIRECTION_45& aOther) const
	{
		if(m_dir == UNDEFINED || aOther.m_dir == UNDEFINED)
			return ANG_UNDEFINED;

		int d = std::abs(m_dir - aOther.m_dir);

		if(d == 1 || d == 7)
			return ANG_OBTUSE;
		else if(d == 2 || d == 6)
			return ANG_RIGHT;
		else if(d == 3 || d == 5)
			return ANG_ACUTE;
		else if(d == 4)
			return ANG_HALF_FULL;
		else
			return ANG_STRAIGHT;
	}

	/**
	 * Function IsObtuse()
	 * @return true, when (this) forms an obtuse angle with aOther
	 */
	bool IsObtuse(const DIRECTION_45& aOther) const
	{
		return Angle(aOther) == ANG_OBTUSE;
	}

	/**
	 * Function IsDiagonal()
	 * Returns true if the direction is diagonal (e.g. North-West, South-East, etc)
	 * @return true, when diagonal.
	 */
	bool IsDiagonal() const
	{
		return (m_dir % 2) == 1;
	}
	
	/**
	 * Function BuildInitialTrace()
	 *
	 * Builds a 2-segment line chain between points aP0 and aP1 and following 45-degree routing
	 * regime. If aStartDiagonal is true, the trace starts with a diagonal segment.
	 * @param aP0 starting point
	 * @param aP1 ending point
	 * @param aStartDiagonal whether the first segment has to be diagonal
	 * @return the trace
	 */
	const SHAPE_LINE_CHAIN BuildInitialTrace(const VECTOR2I& aP0, const VECTOR2I &aP1, bool aStartDiagonal = false) const
	{
		int w = abs(aP1.x - aP0.x);
		int h = abs(aP1.y - aP0.y);	
		int sw = sign(aP1.x - aP0.x);
		int sh = sign(aP1.y - aP0.y);		

		VECTOR2I mp0, mp1;
		
		// we are more horizontal than vertical?
		if(w > h)
		{
			mp0 = VECTOR2I((w - h) * sw, 0); // direction: E
			mp1 = VECTOR2I(h * sw, h * sh);	 // direction: NE
		} else {
			mp0 = VECTOR2I(0, sh * (h - w)); // direction: N
			mp1 = VECTOR2I(sw * w, sh * w);  // direction: NE
		}

		bool start_diagonal;

		if(m_dir == UNDEFINED)
			start_diagonal = aStartDiagonal;
		else
			start_diagonal = IsDiagonal();

		SHAPE_LINE_CHAIN pl;

		pl.Append(aP0);
		if (start_diagonal)
			pl.Append(aP0 + mp1);
		else
			pl.Append(aP0 + mp0);
		
		pl.Append(aP1);
		pl.Simplify();
		return pl;
	};

	bool operator==(const DIRECTION_45& aOther) const
	{
		return aOther.m_dir == m_dir;
	}

	bool operator!=(const DIRECTION_45& aOther) const
	{
		return aOther.m_dir != m_dir;
	}

	const DIRECTION_45 Right() const
	{
		DIRECTION_45 r;
		r.m_dir = (Directions) (m_dir + 1);
		if(r.m_dir == NW)
			r.m_dir = N;
		return r;
	}

private:

	template <typename T> int sign(T val) const {
    	return (T(0) < val) - (val < T(0));
	}

	/** 
	 * Function construct()
	 * Calculates the direction from a vector. If the vector's angle is not a multiple of 45
	 * degrees, the direction is rounded to the nearest octant.
	 * @param aVec our vector
	 */
	void construct(const VECTOR2I& aVec)
	{
		m_dir = UNDEFINED;
		if(aVec.x == 0 && aVec.y == 0)
			return;

		double mag = 360.0 - (180.0 / M_PI * atan2 ((double) aVec.y, (double) aVec.x )) + 90.0;
		if (mag >= 360.0)
			mag -= 360.0;
		if(mag < 0.0)
			mag += 360.0;
 
 		m_dir = (Directions) ((mag + 22.5) / 45.0);

 		if(m_dir >= 8)
 			m_dir = (Directions) (m_dir - 8);
 		if(m_dir < 0)
 			m_dir = (Directions) (m_dir + 8);

 		return ;
		if(aVec.y < 0)
		{
			if(aVec.x > 0)
				m_dir = NE;
			else if(aVec.x < 0)
				m_dir = NW;
			else
				m_dir = N;
		}
		else if(aVec.y == 0)
		{
			if(aVec.x > 0)
				m_dir = E;
			else
				m_dir = W;
		}
		else  // aVec.y>0
		{
			if(aVec.x > 0)
				m_dir = SE;
			else if(aVec.x < 0)
				m_dir = SW;
			else
				m_dir = S;
		}
	}

	Directions m_dir; ///> our actual direction
};		

#endif // __DIRECTION_H