1 files changed, 179 insertions, 0 deletions
diff --git a/gfx/2d/Matrix.cpp b/gfx/2d/Matrix.cpp
new file mode 100644
index 0000000000..cb8830c168
--- /dev/null
+++ b/gfx/2d/Matrix.cpp
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Matrix.h"
+#include "Quaternion.h"
+#include "Tools.h"
+#include <algorithm>
+#include <ostream>
+#include <math.h>
+#include <float.h>  // for FLT_EPSILON
+
+#include "mozilla/FloatingPoint.h"  // for UnspecifiedNaN
+
+namespace mozilla {
+namespace gfx {
+
+/* Force small values to zero.  We do this to avoid having sin(360deg)
+ * evaluate to a tiny but nonzero value.
+ */
+double FlushToZero(double aVal) {
+  // XXX Is double precision really necessary here
+  if (-FLT_EPSILON < aVal && aVal < FLT_EPSILON) {
+    return 0.0f;
+  } else {
+    return aVal;
+  }
+}
+
+/* Computes tan(aTheta).  For values of aTheta such that tan(aTheta) is
+ * undefined or very large, SafeTangent returns a manageably large value
+ * of the correct sign.
+ */
+double SafeTangent(double aTheta) {
+  // XXX Is double precision really necessary here
+  const double kEpsilon = 0.0001;
+
+  /* tan(theta) = sin(theta)/cos(theta); problems arise when
+   * cos(theta) is too close to zero.  Limit cos(theta) to the
+   * range [-1, -epsilon] U [epsilon, 1].
+   */
+
+  double sinTheta = sin(aTheta);
+  double cosTheta = cos(aTheta);
+
+  if (cosTheta >= 0 && cosTheta < kEpsilon) {
+    cosTheta = kEpsilon;
+  } else if (cosTheta < 0 && cosTheta >= -kEpsilon) {
+    cosTheta = -kEpsilon;
+  }
+  return FlushToZero(sinTheta / cosTheta);
+}
+
+template <>
+Matrix Matrix::Rotation(Float aAngle) {
+  Matrix newMatrix;
+
+  Float s = sinf(aAngle);
+  Float c = cosf(aAngle);
+
+  newMatrix._11 = c;
+  newMatrix._12 = s;
+  newMatrix._21 = -s;
+  newMatrix._22 = c;
+
+  return newMatrix;
+}
+
+template <>
+MatrixDouble MatrixDouble::Rotation(Double aAngle) {
+  MatrixDouble newMatrix;
+
+  Double s = sin(aAngle);
+  Double c = cos(aAngle);
+
+  newMatrix._11 = c;
+  newMatrix._12 = s;
+  newMatrix._21 = -s;
+  newMatrix._22 = c;
+
+  return newMatrix;
+}
+
+template <>
+Matrix4x4 MatrixDouble::operator*(const Matrix4x4& aMatrix) const {
+  Matrix4x4 resultMatrix;
+
+  resultMatrix._11 = this->_11 * aMatrix._11 + this->_12 * aMatrix._21;
+  resultMatrix._12 = this->_11 * aMatrix._12 + this->_12 * aMatrix._22;
+  resultMatrix._13 = this->_11 * aMatrix._13 + this->_12 * aMatrix._23;
+  resultMatrix._14 = this->_11 * aMatrix._14 + this->_12 * aMatrix._24;
+
+  resultMatrix._21 = this->_21 * aMatrix._11 + this->_22 * aMatrix._21;
+  resultMatrix._22 = this->_21 * aMatrix._12 + this->_22 * aMatrix._22;
+  resultMatrix._23 = this->_21 * aMatrix._13 + this->_22 * aMatrix._23;
+  resultMatrix._24 = this->_21 * aMatrix._14 + this->_22 * aMatrix._24;
+
+  resultMatrix._31 = aMatrix._31;
+  resultMatrix._32 = aMatrix._32;
+  resultMatrix._33 = aMatrix._33;
+  resultMatrix._34 = aMatrix._34;
+
+  resultMatrix._41 =
+      this->_31 * aMatrix._11 + this->_32 * aMatrix._21 + aMatrix._41;
+  resultMatrix._42 =
+      this->_31 * aMatrix._12 + this->_32 * aMatrix._22 + aMatrix._42;
+  resultMatrix._43 =
+      this->_31 * aMatrix._13 + this->_32 * aMatrix._23 + aMatrix._43;
+  resultMatrix._44 =
+      this->_31 * aMatrix._14 + this->_32 * aMatrix._24 + aMatrix._44;
+
+  return resultMatrix;
+}
+
+// Intersect the polygon given by aPoints with the half space induced by
+// aPlaneNormal and return the resulting polygon. The returned points are
+// stored in aDestBuffer, and its meaningful subspan is returned.
+template <typename F>
+Span<Point4DTyped<UnknownUnits, F>> IntersectPolygon(
+    Span<Point4DTyped<UnknownUnits, F>> aPoints,
+    const Point4DTyped<UnknownUnits, F>& aPlaneNormal,
+    Span<Point4DTyped<UnknownUnits, F>> aDestBuffer) {
+  if (aPoints.Length() < 1 || aDestBuffer.Length() < 1) {
+    return {};
+  }
+
+  size_t nextIndex = 0;  // aDestBuffer[nextIndex] is the next emitted point.
+
+  // Iterate over the polygon edges. In each iteration the current edge
+  // is the edge from *prevPoint to point. If the two end points lie on
+  // different sides of the plane, we have an intersection. Otherwise,
+  // the edge is either completely "inside" the half-space created by
+  // the clipping plane, and we add curPoint, or it is completely
+  // "outside", and we discard curPoint. This loop can create duplicated
+  // points in the polygon.
+  const auto* prevPoint = &aPoints[aPoints.Length() - 1];
+  F prevDot = aPlaneNormal.DotProduct(*prevPoint);
+  for (const auto& curPoint : aPoints) {
+    F curDot = aPlaneNormal.DotProduct(curPoint);
+
+    if ((curDot >= 0.0) != (prevDot >= 0.0)) {
+      // An intersection with the clipping plane has been detected.
+      // Interpolate to find the intersecting curPoint and emit it.
+      F t = -prevDot / (curDot - prevDot);
+      aDestBuffer[nextIndex++] = curPoint * t + *prevPoint * (1.0 - t);
+      if (nextIndex >= aDestBuffer.Length()) {
+        break;
+      }
+    }
+
+    if (curDot >= 0.0) {
+      // Emit any source points that are on the positive side of the
+      // clipping plane.
+      aDestBuffer[nextIndex++] = curPoint;
+      if (nextIndex >= aDestBuffer.Length()) {
+        break;
+      }
+    }
+
+    prevPoint = &curPoint;
+    prevDot = curDot;
+  }
+
+  return aDestBuffer.To(nextIndex);
+}
+
+template Span<Point4DTyped<UnknownUnits, Float>> IntersectPolygon(
+    Span<Point4DTyped<UnknownUnits, Float>> aPoints,
+    const Point4DTyped<UnknownUnits, Float>& aPlaneNormal,
+    Span<Point4DTyped<UnknownUnits, Float>> aDestBuffer);
+template Span<Point4DTyped<UnknownUnits, Double>> IntersectPolygon(
+    Span<Point4DTyped<UnknownUnits, Double>> aPoints,
+    const Point4DTyped<UnknownUnits, Double>& aPlaneNormal,
+    Span<Point4DTyped<UnknownUnits, Double>> aDestBuffer);
+
+}  // namespace gfx
+}  // namespace mozilla