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 * Copyright (c) 2013, Daniel Murphy
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package org.jbox2d.collision.shapes;

import org.jbox2d.collision.AABB;
import org.jbox2d.collision.RayCastInput;
import org.jbox2d.collision.RayCastOutput;
import org.jbox2d.common.Transform;
import org.jbox2d.common.Vec2;

/** A shape is used for collision detection. You can create a shape however you like. Shapes used for simulation in World are
 * created automatically when a Fixture is created. Shapes may encapsulate a one or more child shapes. */
public abstract class Shape {

	public final ShapeType m_type;
	public float m_radius;

	public Shape (ShapeType type) {
		this.m_type = type;
	}

	/** Get the type of this shape. You can use this to down cast to the concrete shape.
	 * 
	 * @return the shape type. */
	public ShapeType getType () {
		return m_type;
	}

	/** The radius of the underlying shape. This can refer to different things depending on the shape implementation
	 * 
	 * @return */
	public float getRadius () {
		return m_radius;
	}

	/** Sets the radius of the underlying shape. This can refer to different things depending on the implementation
	 * 
	 * @param radius */
	public void setRadius (float radius) {
		this.m_radius = radius;
	}

	/** Get the number of child primitives
	 * 
	 * @return */
	public abstract int getChildCount ();

	/** Test a point for containment in this shape. This only works for convex shapes.
	 * 
	 * @param xf the shape world transform.
	 * @param p a point in world coordinates. */
	public abstract boolean testPoint (final Transform xf, final Vec2 p);

	/** Cast a ray against a child shape.
	 * 
	 * @param argOutput the ray-cast results.
	 * @param argInput the ray-cast input parameters.
	 * @param argTransform the transform to be applied to the shape.
	 * @param argChildIndex the child shape index
	 * @return if hit */
	public abstract boolean raycast (RayCastOutput output, RayCastInput input, Transform transform, int childIndex);

	/** Given a transform, compute the associated axis aligned bounding box for a child shape.
	 * 
	 * @param argAabb returns the axis aligned box.
	 * @param argXf the world transform of the shape. */
	public abstract void computeAABB (final AABB aabb, final Transform xf, int childIndex);

	/** Compute the mass properties of this shape using its dimensions and density. The inertia tensor is computed about the local
	 * origin.
	 * 
	 * @param massData returns the mass data for this shape.
	 * @param density the density in kilograms per meter squared. */
	public abstract void computeMass (final MassData massData, final float density);

	/** Compute the distance from the current shape to the specified point. This only works for convex shapes.
	 * 
	 * @param xf the shape world transform.
	 * @param p a point in world coordinates.
	 * @param normalOut returns the direction in which the distance increases.
	 * @return distance returns the distance from the current shape. */
	public abstract float computeDistanceToOut (Transform xf, Vec2 p, int childIndex, Vec2 normalOut);

	public abstract Shape clone ();
}
