Initial commit.

physics/translation.cpp

@@ -0,0 +1,87 @@
+// -*- C++ -*-
+
+#include "particle.h"
+#include "translation.h"
+#include "vector.h"
+
+using namespace mbostock;
+
+Translation::Translation(const Vector& x0, const Vector& x1,
+                         float speed, float start, float dampen)
+    : x0_(x0), x1_(x1), u_(start), s_(speed * ParticleSimulator::timeStep()),
+      kd_(1.f - dampen), v_((x1 - x0) * s_),
+      x_(x0 * (1.f - u_) + x1 * u_), origin_(x_),
+      mode_(REVERSE), reversed_(false) {
+}
+
+void Translation::reset() {
+  origin_ = x_ = x0_ * (1.f - u_) + x1_ * u_;
+  v_ = (x1_ - x0_) * s_;
+  reversed_ = false;
+}
+
+void Translation::step() {
+  if (!enabled()) {
+    return;
+  }
+  Vector x = origin_ + v_;
+  if (reversed_) {
+    if (v_.dot(x0_ - x) < 0.f) {
+      reversed_ = false;
+      v_ *= -1.f;
+    }
+  } else {
+    if (v_.dot(x1_ - x) < 0.f) {
+      switch (mode_) {
+        case REVERSE: {
+          reversed_ = true;
+          v_ *= -1.f;
+          break;
+        }
+        case RESET: {
+          x_ = x0_;
+          origin_ = x0_;
+          break;
+        }
+        case ONE_WAY: {
+          v_ = Vector::ZERO();
+          break;
+        }
+      }
+    }
+  }
+  x_ += v_;
+  dv_ = (x_ - origin_) * kd_;
+  origin_ += dv_;
+}
+
+void Translation::setMode(Mode m) {
+  mode_ = m;
+}
+
+const Vector& Translation::velocity() const {
+  return enabled() ? dv_ : Vector::ZERO();
+}
+
+Vector Translation::point(const Vector& x) const {
+  return x + origin_;
+}
+
+Vector Translation::pointInverse(const Vector& x) const {
+  return x - origin_;
+}
+
+TranslatingShape::TranslatingShape(const Shape& s, const Translation& t)
+    : shape_(s), translation_(t) {
+}
+
+bool TranslatingShape::intersects(const Sphere& s) const {
+  Sphere ts(translation_.pointInverse(s.x()), s.radius());
+  return shape_.intersects(ts);
+}
+
+Projection TranslatingShape::project(const Vector& x) const {
+  Projection p = shape_.project(translation_.pointInverse(x));
+  p.x = translation_.point(p.x);
+  return p;
+}