// tjh2dVector.java

/** A simple class that manages a 2D location/vector in space given floats x and y. */
public class tjh2dVector extends Object
{
	//--------------------------------------------------------------------------------
	// data
	//--------------------------------------------------------------------------------

	/** the coordinates of the location/vector */
	public float x,y;

	//--------------------------------------------------------------------------------
	// methods
	//--------------------------------------------------------------------------------

	/** default constructor */
	public tjh2dVector()
	{
	}

	/** initializing constructor */
	public tjh2dVector(float a,float b)
	{
		x=a;
		y=b;
	}

	/** returns the dot product of the two vectors */
	public static float DotProduct(tjh2dVector a,tjh2dVector b)
	{
		return a.x*b.x+a.y*b.y;
	}

	/** rotates this point by deg degrees around the point c */
	public void RotateAround(tjh2dVector c,float deg)
	{
		// find sine and cosine of the angle
		float radians = deg*3.1415926535F/180.0F;
		float sine = (float)Math.sin(radians);
		float cosine = (float)Math.cos(radians);
		
		// rotate around the point
		tjh2dVector new_pos = new tjh2dVector(x-c.x,y-c.y);
		float temp = cosine*new_pos.x - sine*new_pos.y;
		new_pos.y = sine*new_pos.x + cosine*new_pos.y;
		new_pos.x = temp;
		x = c.x + new_pos.x;
		y = c.y + new_pos.y;
	}

	/** replaces this vector with its left-hand perpendicular */
	public tjh2dVector Perp()
	{
		tjh2dVector v = new tjh2dVector();
		v.x=-y;
		v.y=x;
		return v;
	}

	/** changes the length of the vector to one */
	public tjh2dVector Normalize()
	{
		float l = Length();
		tjh2dVector v = new tjh2dVector();
		v.x=x/l;
		v.y=y/l;
		return v;
	}

	/** returns the length of the vector */
	public float Length()
	{
		return (float)Math.sqrt(x*x+y*y);
	}

	/** return the unit vector with the correct angle anti-clockwise from the +ve x-axis */
	public static tjh2dVector Cartesian(float degrees)
	{
		tjh2dVector v = new tjh2dVector();
		v.x=(float)Math.cos(degrees*3.1415926535F/180.0F);
		v.y=(float)Math.sin(degrees*3.1415926535F/180.0F);
		return v;
	}

	/** returns the angle of the vector anticlockwise from the +ve x-axis */
	public float Angle()
	{
		return (float)Math.atan2(x,y);
	}

	/** adds the two vectors together, returns the result */
	public static tjh2dVector sum(tjh2dVector a,tjh2dVector b)
	{
		tjh2dVector v = new tjh2dVector();
		v.x=a.x+b.x;
		v.y=a.y+b.y;
		return v;
	}

	/** subtracts b from a, returns the result */
	public static tjh2dVector minus(tjh2dVector a,tjh2dVector b)
	{
		tjh2dVector v = new tjh2dVector();
		v.x=a.x-b.x;
		v.y=a.y-b.y;
		return v;
	}

	/** multiplies the vector a by the scalar f, returns the result */
	public static tjh2dVector mult(tjh2dVector a,float f)
	{
		tjh2dVector v = new tjh2dVector();
		v.x=a.x*f;
		v.y=a.y*f;
		return v;
	}
}