/*
* gleem -- OpenGL Extremely Easy-To-Use Manipulators.
* Copyright (C) 1998-2003 Kenneth B. Russell (kbrussel@alum.mit.edu)
*
* Copying, distribution and use of this software in source and binary
* forms, with or without modification, is permitted provided that the
* following conditions are met:
*
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* this list of conditions and the following disclaimer in the source
* code header files; and Distributions of binary code must reproduce
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* other materials provided with the software distribution.
*
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* holder may not be used to endorse or promote products derived from
* this software without specific prior written permission.
*
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* KIND. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
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*/
package gleem.linalg;
/** This differs from the Plane class in that it maintains an origin
and orthonormal U, V axes in the plane so that it can project a 3D
point to a 2D one. U cross V = normal. U and V coordinates are
computed with respect to the origin. */
public class PlaneUV {
private Vec3f origin = new Vec3f();
/** Normalized */
private Vec3f normal = new Vec3f();
private Vec3f uAxis = new Vec3f();
private Vec3f vAxis = new Vec3f();
/** Default constructor initializes normal to (0, 1, 0), origin to
(0, 0, 0), U axis to (1, 0, 0) and V axis to (0, 0, -1). */
public PlaneUV() {
setEverything(new Vec3f(0, 1, 0),
new Vec3f(0, 0, 0),
new Vec3f(1, 0, 0),
new Vec3f(0, 0, -1));
}
/** Takes normal vector and a point which the plane goes through
(which becomes the plane's "origin"). Normal does NOT have to be
normalized, but may not be zero vector. U and V axes are
initialized to arbitrary values. */
public PlaneUV(Vec3f normal, Vec3f origin) {
setOrigin(origin);
setNormal(normal);
}
/** Takes normal vector, point which plane goes through, and the "u"
axis in the plane. Computes the "v" axis by taking the cross
product of the normal and the u axis. Axis must be perpendicular
to normal. Normal and uAxis do NOT have to be normalized, but
neither may be the zero vector. */
public PlaneUV(Vec3f normal,
Vec3f origin,
Vec3f uAxis) {
setOrigin(origin);
setNormalAndU(normal, uAxis);
}
/** Takes normal vector, point which plane goes through, and both
the u and v axes. u axis cross v axis = normal. Normal, uAxis, and
vAxis do NOT have to be normalized, but none may be the zero
vector. */
public PlaneUV(Vec3f normal,
Vec3f origin,
Vec3f uAxis,
Vec3f vAxis) {
setEverything(normal, origin, uAxis, vAxis);
}
/** Set the origin, through which this plane goes and with respect
to which U and V coordinates are computed */
public void setOrigin(Vec3f origin) {
this.origin.set(origin);
}
public Vec3f getOrigin() {
return new Vec3f(origin);
}
/** Normal, U and V axes must be orthogonal and satisfy U cross V =
normal, do not need to be unit length but must not be the zero
vector. */
public void setNormalAndUV(Vec3f normal,
Vec3f uAxis,
Vec3f vAxis) {
setEverything(normal, origin, uAxis, vAxis);
}
/** This version sets the normal vector and generates new U and V
axes. */
public void setNormal(Vec3f normal) {
Vec3f uAxis = new Vec3f();
MathUtil.makePerpendicular(normal, uAxis);
Vec3f vAxis = normal.cross(uAxis);
setEverything(normal, origin, uAxis, vAxis);
}
/** This version computes the V axis from (normal cross U). */
public void setNormalAndU(Vec3f normal,
Vec3f uAxis) {
Vec3f vAxis = normal.cross(uAxis);
setEverything(normal, origin, uAxis, vAxis);
}
/** Normal, U and V axes are normalized internally, so, for example,
<b>normal</b> is not necessarily equal to
<code>plane.setNormal(normal); plane.getNormal();</code> */
public Vec3f getNormal() {
return normal;
}
public Vec3f getUAxis() {
return uAxis;
}
public Vec3f getVAxis() {
return vAxis;
}
/** Project a point onto the plane */
public void projectPoint(Vec3f point,
Vec3f projPt,
Vec2f uvCoords) {
// Using projPt as a temporary
projPt.sub(point, origin);
float dotp = normal.dot(projPt);
// Component perpendicular to plane
Vec3f tmpDir = new Vec3f();
tmpDir.set(normal);
tmpDir.scale(dotp);
projPt.sub(projPt, tmpDir);
// Take dot products with basis vectors
uvCoords.set(projPt.dot(uAxis),
projPt.dot(vAxis));
// Add on center to intersection point
projPt.add(origin);
}
/** Intersect a ray with this plane, outputting not only the 3D
intersection point but also the U, V coordinates of the
intersection. Returns true if intersection occurred, false
otherwise. This is a two-sided ray cast. */
public boolean intersectRay(Vec3f rayStart,
Vec3f rayDirection,
IntersectionPoint intPt,
Vec2f uvCoords) {
float denom = rayDirection.dot(normal);
if (denom == 0.0f)
return false;
Vec3f tmpDir = new Vec3f();
tmpDir.sub(origin, rayStart);
float t = tmpDir.dot(normal) / denom;
// Find intersection point
Vec3f tmpPt = new Vec3f();
tmpPt.set(rayDirection);
tmpPt.scale(t);
tmpPt.add(rayStart);
intPt.setIntersectionPoint(tmpPt);
intPt.setT(t);
// Find UV coords
tmpDir.sub(intPt.getIntersectionPoint(), origin);
uvCoords.set(tmpDir.dot(uAxis), tmpDir.dot(vAxis));
return true;
}
private void setEverything(Vec3f normal,
Vec3f origin,
Vec3f uAxis,
Vec3f vAxis) {
this.normal.set(normal);
this.origin.set(origin);
this.uAxis.set(uAxis);
this.vAxis.set(vAxis);
this.normal.normalize();
this.uAxis.normalize();
this.vAxis.normalize();
}
}