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(float t) {
  26       PVector pt = PVector.mult(vector, t);
  27       pt.add(origin);
  28       return pt;
  29     }
  30
  31     boolean isColinear(PVector pt) {
  32       PVector projected = projected(pt);
  33       return projected.x==pt.x && projected.y==pt.y && projected.z==pt.z;
  34     }
  35
  36     float getTValue(PVector pt) {
  37       PVector subtraction = PVector.sub(pt, origin);
  38       return subtraction.dot(vector);
  39     }
  40
  41     PVector projected(PVector pt) {
  42       return getPointAt(getTValue(pt));
  43     }
  44
  45     PVector rotatePoint(PVector pt, float rads) {
  46       Vec3D axisVec3D = new Vec3D(vector.x, vector.y, vector.z);
  47       Matrix4x4 mat = new Matrix4x4();
  48       mat.rotateAroundAxis(axisVec3D, rads);
  49       Vec3D ptVec3D = new Vec3D(pt.x, pt.y, pt.z);
  50       Vec3D rotatedPt = mat.applyTo(ptVec3D);
  51       return new PVector(rotatedPt.x, rotatedPt.y, rotatedPt.z);
  52     }
  53   }
  54
  55   private class Helix {
  56     private final Line axis;
  57     private final float period;
  58     private final float rotationPeriod;
  59     private final float radius;
  60     private final float girth;
  61     private final PVector referencePoint;
  62     private float phase;
  63     private PVector phaseNormal;
  64
  65     Helix(Line axis, float period, float radius, float girth, float phase, float rotationPeriod) {
  66       this.axis = axis;
  67       this.period = period;
  68       this.radius = radius;
  69       this.girth = girth;
  70       this.phase = phase;
  71       this.rotationPeriod = rotationPeriod;
  72
  73       // Generate a normal that will rotate to
  74       // produce the helical shape.
  75       PVector pt = new PVector(0, 1, 0);
  76       if (this.axis.isColinear(pt)) {
  77         pt = new PVector(0, 0, 1);
  78         if (this.axis.isColinear(pt)) {
  79           pt = new PVector(0, 1, 1);
  80         }
  81       }
  82
  83       this.referencePoint = pt;
  84       this.phase = phase;
  85
  86       setPhaseNormalFromPhase();
  87     }
  88
  89     private void setPhaseNormalFromPhase() {
  90       phaseNormal = axis.getVector().cross(axis.rotatePoint(referencePoint, phase));
  91       phaseNormal.normalize();
  92       phaseNormal.mult(radius);
  93     }
  94
  95     private void setPhase(float phase) {
  96       this.phase = phase;
  97       setPhaseNormalFromPhase();
  98     }
  99
 100     void step(int deltaMs) {
 101       setPhase(phase + (deltaMs / rotationPeriod) * TWO_PI);
 102     }
 103
 104     PVector pointOnToroidalAxis(float t) {
 105       PVector p = axis.getPointAt(t);
 106       PVector middle = PVector.add(p, phaseNormal);
 107       return axis.rotatePoint(middle, (t / period) * TWO_PI);
 108     }
 109
 110     color colorOfPoint(PVector p) {
 111       // Calculate the projection of this point to the axis.
 112       PVector projectedPoint = axis.projected(p);
 113
 114       // Find the appropriate point for the current rotation
 115       // of the helix.
 116       float t = axis.getTValue(projectedPoint);
 117       PVector toroidPoint = pointOnToroidalAxis(t);
 118
 119       // The rotated point represents the middle of the girth of
 120       // the helix.  Figure out if the current point is inside that
 121       // region.
 122       float d = PVector.dist(p, toroidPoint);
 123       boolean inToroid = d < girth;
 124
 125       // Soften edges by fading brightness
 126       float b = constrain(100*(1 - ((d-.5*girth)/(girth*.5))), 0, 100);
 127       return color((lx.getBaseHuef() + (360*(phase / TWO_PI)))%360, (inToroid ? 80 : 0), b);
 128     }
 129   }
 130
 131   private final Helix h1;
 132   private final Helix h2;
 133
 134   private final BasicParameter helix1On = new BasicParameter("H1ON", 1);
 135   private final BasicParameter helix2On = new BasicParameter("H2ON", 1);
 136
 137   public HelixPattern(GLucose glucose) {
 138     super(glucose);
 139
 140     addParameter(helix1On);
 141     addParameter(helix2On);
 142
 143     h1 = new Helix(
 144       new Line(new PVector(100, 50, 70), new PVector(1,0,0)),
 145       700, // period
 146       50, // radius
 147       30, // girth
 148       0,  // phase
 149       10000); // rotation period (ms)
 150     h2 = new Helix(
 151       new Line(new PVector(100, 50, 70), new PVector(1,0,0)),
 152       700,
 153       50,
 154       30,
 155       PI,
 156       10000);
 157
 158     // TODO(shaheen) calculate line segments between
 159     // toroidal points selected by stepping the
 160     // parameterized t value.  select base pairs and
 161     // associated colors.  lerp between colors for each
 162     // base pair to produce a DNA effect.
 163
 164   }
 165
 166   void run(int deltaMs) {
 167     boolean h1on = helix1On.getValue() > 0.5;
 168     boolean h2on = helix2On.getValue() > 0.5;
 169
 170     h1.step(deltaMs);
 171     h2.step(deltaMs);
 172
 173     for (Point p : model.points) {
 174       color h1c = color(0,0,0);
 175       color h2c = color(0,0,0);
 176
 177       if (h1on) {
 178         h1c = h1.colorOfPoint(new PVector(p.x,p.y,p.z));
 179       }
 180
 181       if (h2on) {
 182         h2c = h2.colorOfPoint(new PVector(p.x,p.y,p.z));
 183       }
 184
 185       // The helices are positioned to not overlap.  If that changes,
 186       // a better blending formula is probably needed.
 187       colors[p.index] = blendColor(h1c, h2c, ADD);
 188     }
 189   }
 190 }
 191