ShaheenGandhi.pde

   1 import toxi.geom.Vec3D;
   2 import toxi.geom.Matrix4x4;
   3
   4 class HelixPattern extends SCPattern {
   5
   6   // Stores a line in point + vector form
   7   private class Line {
   8     private final PVector origin;
   9     private final PVector vector;
  10
  11     Line(PVector pt, PVector v) {
  12       origin = pt;
  13       vector = v.get();
  14       vector.normalize();
  15     }
  16
  17     PVector getPoint() {
  18       return origin;
  19     }
  20
  21     PVector getVector() {
  22       return vector;
  23     }
  24
  25     PVector getPointAt(final float t) {
  26       return PVector.add(origin, PVector.mult(vector, t));
  27     }
  28
  29     boolean isColinear(final PVector pt) {
  30       PVector projected = projectPoint(pt);
  31       return projected.x==pt.x && projected.y==pt.y && projected.z==pt.z;
  32     }
  33
  34     float getTValue(final PVector pt) {
  35       PVector subtraction = PVector.sub(pt, origin);
  36       return subtraction.dot(vector);
  37     }
  38
  39     PVector projectPoint(final PVector pt) {
  40       return getPointAt(getTValue(pt));
  41     }
  42
  43     PVector rotatePoint(final PVector pt, final float rads) {
  44       Vec3D axisVec3D = new Vec3D(vector.x, vector.y, vector.z);
  45       Vec3D originVec3D = new Vec3D(origin.x, origin.y, origin.z);
  46       Matrix4x4 mat = new Matrix4x4().identity()
  47         .rotateAroundAxis(axisVec3D, rads);
  48       Vec3D ptVec3D = new Vec3D(pt.x, pt.y, pt.z).sub(originVec3D);
  49       Vec3D rotatedPt = mat.applyTo(ptVec3D).add(originVec3D);
  50       return new PVector(rotatedPt.x, rotatedPt.y, rotatedPt.z);
  51     }
  52   }
  53
  54   private class Helix {
  55     private final Line axis;
  56     private final float period; // period of coil
  57     private final float rotationPeriod; // animation period
  58     private final float radius; // radius of coil
  59     private final float girth; // girth of coil
  60     private final PVector referencePoint;
  61     private float phase;
  62     private PVector phaseNormal;
  63
  64     Helix(Line axis, float period, float radius, float girth, float phase, float rotationPeriod) {
  65       this.axis = axis;
  66       this.period = period;
  67       this.radius = radius;
  68       this.girth = girth;
  69       this.phase = phase;
  70       this.rotationPeriod = rotationPeriod;
  71
  72       // Generate a normal that will rotate to
  73       // produce the helical shape.
  74       PVector pt = new PVector(0, 1, 0);
  75       if (this.axis.isColinear(pt)) {
  76         pt = new PVector(0, 0, 1);
  77         if (this.axis.isColinear(pt)) {
  78           pt = new PVector(0, 1, 1);
  79         }
  80       }
  81
  82       this.referencePoint = pt;
  83
  84       // The normal is calculated by the cross product of the axis
  85       // and a random point that is not colinear with it.
  86       phaseNormal = axis.getVector().cross(referencePoint);
  87       phaseNormal.normalize();
  88       phaseNormal.mult(radius);
  89     }
  90
  91     Line getAxis() {
  92       return axis;
  93     }
  94
  95     void step(int deltaMs) {
  96       // Rotate
  97       if (rotationPeriod != 0) {
  98         this.phase = (phase + ((float)deltaMs / (float)rotationPeriod) * TWO_PI);
  99       }
 100     }
 101
 102     PVector pointOnToroidalAxis(float t) {
 103       PVector p = axis.getPointAt(t);
 104       PVector middle = PVector.add(p, phaseNormal);
 105       return axis.rotatePoint(middle, (t / period) * TWO_PI + phase);
 106     }
 107
 108     color colorOfPoint(final PVector p) {
 109       // Find the appropriate point for the current rotation
 110       // of the helix.
 111       float t = axis.getTValue(p);
 112       PVector toroidPoint = pointOnToroidalAxis(t);
 113
 114       // The rotated point represents the middle of the girth of
 115       // the helix.  Figure out if the current point is inside that
 116       // region.
 117       float d = PVector.dist(p, toroidPoint);
 118
 119       // Soften edges by fading brightness.
 120       float b = constrain(100*(1 - ((d-.5*girth)/(girth*.5))), 0, 100);
 121       return color((lx.getBaseHuef() + (360*(phase / TWO_PI)))%360, 80, b);
 122     }
 123   }
 124
 125   private final Helix h1;
 126   private final Helix h2;
 127
 128   private final BasicParameter helix1On = new BasicParameter("H1ON", 1);
 129   private final BasicParameter helix2On = new BasicParameter("H2ON", 1);
 130
 131   public HelixPattern(GLucose glucose) {
 132     super(glucose);
 133
 134     addParameter(helix1On);
 135     addParameter(helix2On);
 136
 137     h1 = new Helix(
 138       new Line(new PVector(100, 50, 45), new PVector(1,0,0)),
 139       100, // period
 140       40, // radius
 141       30, // girth
 142       0,  // phase
 143       10000); // rotation period (ms)
 144     h2 = new Helix(
 145       new Line(new PVector(100, 50, 70), new PVector(1,0,0)),
 146       100,
 147       40,
 148       30,
 149       PI,
 150       10000);
 151
 152     // TODO(shaheen) calculate line segments between
 153     // toroidal points selected by stepping the
 154     // parameterized t value.  select base pairs and
 155     // associated colors.  lerp between colors for each
 156     // base pair to produce a DNA effect.
 157
 158   }
 159
 160   void run(int deltaMs) {
 161     boolean h1on = helix1On.getValue() > 0.5;
 162     boolean h2on = helix2On.getValue() > 0.5;
 163
 164     h1.step(deltaMs);
 165     h2.step(deltaMs);
 166
 167     for (Point p : model.points) {
 168       color h1c = color(0,0,0);
 169       color h2c = color(0,0,0);
 170
 171       if (h1on) {
 172         h1c = h1.colorOfPoint(new PVector(p.x,p.y,p.z));
 173       }
 174
 175       if (h2on) {
 176         h2c = h2.colorOfPoint(new PVector(p.x,p.y,p.z));
 177       }
 178
 179       // The helices are positioned to not overlap.  If that changes,
 180       // a better blending formula is probably needed.
 181       colors[p.index] = blendColor(h1c, h2c, ADD);
 182     }
 183   }
 184 }
 185