1 files changed, 93 insertions, 0 deletions
diff --git a/gfx/thebes/gfxQuaternion.h b/gfx/thebes/gfxQuaternion.h
new file mode 100644
index 000000000..e25974974
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+++ b/gfx/thebes/gfxQuaternion.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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/. */
+
+#ifndef GFX_QUATERNION_H
+#define GFX_QUATERNION_H
+
+#include "mozilla/gfx/BasePoint4D.h"
+#include "mozilla/gfx/Matrix.h"
+#include "nsAlgorithm.h"
+#include <algorithm>
+
+struct gfxQuaternion : public mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> {
+    typedef mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> Super;
+
+    gfxQuaternion() : Super() {}
+    gfxQuaternion(gfxFloat aX, gfxFloat aY, gfxFloat aZ, gfxFloat aW) : Super(aX, aY, aZ, aW) {}
+
+    explicit gfxQuaternion(const mozilla::gfx::Matrix4x4& aMatrix) {
+        w = 0.5 * sqrt(std::max(1 + aMatrix[0][0] + aMatrix[1][1] + aMatrix[2][2], 0.0f));
+        x = 0.5 * sqrt(std::max(1 + aMatrix[0][0] - aMatrix[1][1] - aMatrix[2][2], 0.0f));
+        y = 0.5 * sqrt(std::max(1 - aMatrix[0][0] + aMatrix[1][1] - aMatrix[2][2], 0.0f));
+        z = 0.5 * sqrt(std::max(1 - aMatrix[0][0] - aMatrix[1][1] + aMatrix[2][2], 0.0f));
+
+        if(aMatrix[2][1] > aMatrix[1][2])
+            x = -x;
+        if(aMatrix[0][2] > aMatrix[2][0])
+            y = -y;
+        if(aMatrix[1][0] > aMatrix[0][1])
+            z = -z;
+    }
+
+    // Convert from |direction axis, angle| pair to gfxQuaternion.
+    //
+    // Reference:
+    // https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation
+    //
+    // if the direction axis is (x, y, z) = xi + yj + zk,
+    // and the angle is |theta|, this formula can be done using
+    // an extension of Euler's formula:
+    //   q = cos(theta/2) + (xi + yj + zk)(sin(theta/2))
+    //     = cos(theta/2) +
+    //       x*sin(theta/2)i + y*sin(theta/2)j + z*sin(theta/2)k
+    // Note: aDirection should be an unit vector and
+    //       the unit of aAngle should be Radian.
+    gfxQuaternion(const mozilla::gfx::Point3D &aDirection, gfxFloat aAngle) {
+        MOZ_ASSERT(mozilla::gfx::FuzzyEqual(aDirection.Length(), 1.0f),
+                   "aDirection should be an unit vector");
+        x = aDirection.x * sin(aAngle/2.0);
+        y = aDirection.y * sin(aAngle/2.0);
+        z = aDirection.z * sin(aAngle/2.0);
+        w = cos(aAngle/2.0);
+    }
+
+    gfxQuaternion Slerp(const gfxQuaternion &aOther, gfxFloat aCoeff) {
+        gfxFloat dot = mozilla::clamped(DotProduct(aOther), -1.0, 1.0);
+        if (dot == 1.0) {
+            return *this;
+        }
+
+        gfxFloat theta = acos(dot);
+        gfxFloat rsintheta = 1/sqrt(1 - dot*dot);
+        gfxFloat rightWeight = sin(aCoeff*theta)*rsintheta;
+
+        gfxQuaternion left = *this;
+        gfxQuaternion right = aOther;
+
+        left *= cos(aCoeff*theta) - dot*rightWeight;
+        right *= rightWeight;
+
+        return left + right;
+    }
+
+    mozilla::gfx::Matrix4x4 ToMatrix() {
+      mozilla::gfx::Matrix4x4 temp;
+
+        temp[0][0] = 1 - 2 * (y * y + z * z);
+        temp[0][1] = 2 * (x * y + w * z);
+        temp[0][2] = 2 * (x * z - w * y);
+        temp[1][0] = 2 * (x * y - w * z);
+        temp[1][1] = 1 - 2 * (x * x + z * z);
+        temp[1][2] = 2 * (y * z + w * x);
+        temp[2][0] = 2 * (x * z + w * y);
+        temp[2][1] = 2 * (y * z - w * x);
+        temp[2][2] = 1 - 2 * (x * x + y * y);
+
+        return temp;
+    }
+
+};
+
+#endif /* GFX_QUATERNION_H */