X-Git-Url: http://git.megacz.com/?p=anneal.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fqfat%2Fgeom%2FPlane.java;h=966eebfaf72f717ea09a0e1d018c5168e57b00ab;hp=1789e55aee635d8773cdff9b74963f8cfce8a9d3;hb=HEAD;hpb=de2400d58116bd995e73baf7a429e22def1e4067

diff --git a/src/edu/berkeley/qfat/geom/Plane.java b/src/edu/berkeley/qfat/geom/Plane.java
index 1789e55..966eebf 100644
--- a/src/edu/berkeley/qfat/geom/Plane.java
+++ b/src/edu/berkeley/qfat/geom/Plane.java
@@ -1,27 +1,109 @@
 package edu.berkeley.qfat.geom;
 import javax.media.opengl.*;
 
-public class Plane {
+// FEATURE: represent a plane by the matrix that projects points onto that plane?
+public class Plane implements AffineConstraint {
 
-    // FIXME: could be given by
     // ax+by+cz=d
+    public final float a, b, c, d;
+    public final Point p;
 
-    public final Vec norm;
-    public final float dvalue;
+    public Vec norm() { return new Vec(a, b, c).norm(); }
 
     public Plane(Point p, Vec norm) {
-        this.norm = norm.norm();
-        this.dvalue = p.x*this.norm.x+p.y*this.norm.y+p.z*this.norm.z;
+        norm = norm.norm();
+        this.a = norm.x;
+        this.b = norm.y;
+        this.c = norm.z;
+        this.d = p.x*norm.x+p.y*norm.y+p.z*norm.z;
+        this.p = p;
+    }
+
+    public Plane(float a, float b, float c, float d) {
+        // FIXME, what if c==0?
+        this(a, b, c, d, new Point(0, 0, d/c));
+    }
+
+    /** provided at least one of a,b,c is nonzero, return the Plane representing ax+by+cz=d */
+    public Plane(float a, float b, float c, float d, Point p) {
+        this.a = a;
+        this.b = b;
+        this.c = c;
+        this.d = d;
+        this.p = p;
     }
 
     public Point intersect(Plane p1, Plane p2) {
+        Vec norm = norm();
         Plane p3 = this;
-        float z = p1.norm.dot(p2.norm.cross(p3.norm));
+        float z = p1.norm().dot(p2.norm().cross(p3.norm()));
         if (Math.abs(z) < 0.0001) return null;  // planes do not intersect at a point
-        Vec v1 = p2.norm.cross(p3.norm).times(-1 * p1.dvalue);
-        Vec v2 = p3.norm.cross(p1.norm).times(-1 * p2.dvalue);
-        Vec v3 = p1.norm.cross(p2.norm).times(-1 * p3.dvalue);
+        Vec v1 = p2.norm().cross(p3.norm()).times(-1 * p1.d);
+        Vec v2 = p3.norm().cross(p1.norm()).times(-1 * p2.d);
+        Vec v3 = p1.norm().cross(p2.norm()).times(-1 * p3.d);
         return Point.ZERO.plus(v1.plus(v2).plus(v3).times(1/z));
     }
 
+    public AffineConstraint intersect(AffineConstraint c, float epsilon) {
+        if (c instanceof Plane) {
+            Plane p = (Plane)c;
+
+            // same plane
+            if (Math.abs(p.a*this.d-this.a*p.d) <= epsilon &&
+                Math.abs(p.b*this.d-this.b*p.d) <= epsilon &&
+                Math.abs(p.c*this.d-this.c*p.d) <= epsilon &&
+                Math.abs(p.d*this.d-this.d*p.d) <= epsilon)
+                return this;
+
+            // parallel planes
+            if (Math.abs(p.norm().cross(norm()).mag()) <= epsilon)
+                return AffineConstraint.NONE;
+
+            Vec u = norm().cross(p.norm());
+            Point point = null;
+            if (Math.abs(u.z) >= Math.abs(u.y) && Math.abs(u.z) >= Math.abs(u.y)) {
+                point = new Point( (this.b*p.d - p.b*this.d)/(this.a*p.b - p.a*this.b),
+                                   (this.d*p.a - p.d*this.a)/(this.a*p.b - p.a*this.b),
+                                   0);
+            } else if (Math.abs(u.y) >= Math.abs(u.z) && Math.abs(u.y) >= Math.abs(u.x)) {
+                point = new Point( (this.c*p.d - p.c*this.d)/(this.a*p.c - p.a*this.c),
+                                   0,
+                                   (this.d*p.a - p.d*this.a)/(this.a*p.c - p.a*this.c));
+            } else {
+                point = new Point( 0,
+                                   (this.c*p.d - p.c*this.d)/(this.b*p.c - p.b*this.c),
+                                   (this.d*p.b - p.d*this.b)/(this.b*p.c - p.b*this.c));
+            }
+
+            return new Line(point, u);
+
+        } else if (c instanceof Line) {
+            Line l = (Line)c;
+            if (Math.abs(a + b*l.m + this.c*l.n)     <= epsilon &&
+                Math.abs(b * l.c   + this.c*l.d + d) <= epsilon)
+                return l;
+
+            // FIXME: parallel case
+
+            float x = (d - b*l.c - this.c*l.d) / (a + b*l.m + this.c*l.n);
+            float y = l.m*x+l.c;
+            float z = l.n*x+l.d;
+            return new Point(x,y,z);
+            //throw new RuntimeException("not yet implemented");
+
+        } else
+            return c.intersect(this, epsilon);
+    }
+
+    public AffineConstraint multiply(Matrix m) {
+        return new Plane( m.times(p), m.times(norm()).norm() );
+    }
+
+    public Point getProjection(Point p) {
+        Point ret = norm().times(p.minus(this.p).dot(norm())).times(-1).plus(p);
+        return ret;
+    }
+    public String toString() {
+        return "[plane "+a+"x+"+b+"y+"+c+"z="+d+"]";
+    }
 }