edu.mines.jtk.sgl.MouseOnPlane Maven / Gradle / Ivy
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Copyright 2004, Colorado School of Mines and others.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
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package edu.mines.jtk.sgl;
import java.awt.event.MouseEvent;
/**
* A mouse constrained by a plane. Constrained points (in local coordinates)
* lie on a constraint plane that contains a specified origin point and is
* parallel to a specified plane.
*
* Given a mouse event with pixel (x,y) coordinates, a mouse-on-plane computes
* a constrained point. When the mouse pixel coordinates equal those used to
* construct the mouse-on-plane, the constrained point equals the specified
* origin point.
* @author Dave Hale, Colorado School of Mines
* @version 2005.07.05
*/
public class MouseOnPlane extends MouseConstrained {
/**
* Constructs a mouse constrained by a plane. The constraint plane contains
* the specified origin point and is parallel to the specified plane. The
* origin point is typically near, but not necessarily on, the specified
* plane.
* @param event the initial mouse event.
* @param origin the origin point, in local coordinates.
* @param plane the plane, in local coordinates.
* @param localToPixel the transform from local to pixel coordinates.
*/
public MouseOnPlane(
MouseEvent event, Point3 origin, Plane plane, Matrix44 localToPixel)
{
super(localToPixel);
//_origin = new Point3(origin);
_normal = plane.getNormal();
_plane = new Plane(plane);
_delta = origin.minus(getPointOnPlane(event));
}
/**
* Gets the constrained point in local coordinates for the specified event.
* The constrained point lies in the constraint plane that contains the
* origin point.
* @param event the mouse event.
* @return the constrained point, in local coordinates.
*/
public Point3 getPoint(MouseEvent event) {
return getPointOnPlane(event).plusEquals(_delta);
}
///////////////////////////////////////////////////////////////////////////
// private
//private Point3 _origin; // the specified point in the constraint plane
private Vector3 _normal; // unit-vector normal to plane
private Plane _plane; // the specified plane
private Vector3 _delta; // specified origin minus initial intersection point
/**
* Gets point on plane corresponding to the specified mouse event.
* The point is the intersection of the mouse segment with the plane.
*
* Here, the plane is that specified when this mouse-on-plane was
* constructed. That specified plane is parallel to the constraint
* plane that contains the origin.
*/
private Point3 getPointOnPlane(MouseEvent event) {
// Ray from near point A through far point B of mouse segment.
Segment segment = getMouseSegment(event);
Point3 a = segment.getA();
Point3 b = segment.getB();
Vector3 d = b.minus(a);
// Point where the mouse segment intersects the specified plane.
double den = d.dot(_normal);
// TODO: handle case where denominator is tiny (ray parallel to plane)?
double num = -_plane.distanceTo(a);
double t = num/den;
Point3 point;
if (t<=0.0) {
point = a;
} else if (t>=1.0) {
point = b;
} else {
point = a.plus(d.times(t));
}
return point;
}
}