gfx/thebes/gfxQuaternion.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef GFX_QUATERNION_H
   7 #define GFX_QUATERNION_H
   8
   9 #include "mozilla/gfx/BasePoint4D.h"
  10 #include "mozilla/gfx/Matrix.h"
  11 #include "nsAlgorithm.h"
  12 #include <algorithm>
  13
  14 struct gfxQuaternion
  15     : public mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> {
  16   typedef mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> Super;
  17
  18   gfxQuaternion() : Super() {}
  19   gfxQuaternion(gfxFloat aX, gfxFloat aY, gfxFloat aZ, gfxFloat aW)
  20       : Super(aX, aY, aZ, aW) {}
  21
  22   explicit gfxQuaternion(const mozilla::gfx::Matrix4x4& aMatrix) {
  23     w = 0.5 *
  24         sqrt(std::max(1 + aMatrix[0][0] + aMatrix[1][1] + aMatrix[2][2], 0.0f));
  25     x = 0.5 *
  26         sqrt(std::max(1 + aMatrix[0][0] - aMatrix[1][1] - aMatrix[2][2], 0.0f));
  27     y = 0.5 *
  28         sqrt(std::max(1 - aMatrix[0][0] + aMatrix[1][1] - aMatrix[2][2], 0.0f));
  29     z = 0.5 *
  30         sqrt(std::max(1 - aMatrix[0][0] - aMatrix[1][1] + aMatrix[2][2], 0.0f));
  31
  32     if (aMatrix[2][1] > aMatrix[1][2]) x = -x;
  33     if (aMatrix[0][2] > aMatrix[2][0]) y = -y;
  34     if (aMatrix[1][0] > aMatrix[0][1]) z = -z;
  35   }
  36
  37   gfxQuaternion Slerp(const gfxQuaternion& aOther, gfxFloat aCoeff) const {
  38     gfxFloat dot = mozilla::clamped(DotProduct(aOther), -1.0, 1.0);
  39     if (dot == 1.0) {
  40       return *this;
  41     }
  42
  43     gfxFloat theta = acos(dot);
  44     gfxFloat rsintheta = 1 / sqrt(1 - dot * dot);
  45     gfxFloat rightWeight = sin(aCoeff * theta) * rsintheta;
  46
  47     gfxQuaternion left = *this;
  48     gfxQuaternion right = aOther;
  49
  50     left *= cos(aCoeff * theta) - dot * rightWeight;
  51     right *= rightWeight;
  52
  53     return left + right;
  54   }
  55
  56   using Super::operator*=;
  57
  58   // Quaternion multiplication
  59   // Reference:
  60   // https://en.wikipedia.org/wiki/Quaternion#Ordered_list_form
  61   //
  62   // (w1, x1, y1, z1)(w2, x2, y2, z2) = (w1w2 - x1x2 - y1y2 - z1z2,
  63   //                                     w1x2 + x1w2 + y1z2 - z1y2,
  64   //                                     w1y2 - x1z2 + y1w2 + z1x2,
  65   //                                     w1z2 + x1y2 - y1x2 + z1w2)
  66   gfxQuaternion operator*(const gfxQuaternion& aOther) const {
  67     return gfxQuaternion(
  68         w * aOther.x + x * aOther.w + y * aOther.z - z * aOther.y,
  69         w * aOther.y - x * aOther.z + y * aOther.w + z * aOther.x,
  70         w * aOther.z + x * aOther.y - y * aOther.x + z * aOther.w,
  71         w * aOther.w - x * aOther.x - y * aOther.y - z * aOther.z);
  72   }
  73   gfxQuaternion& operator*=(const gfxQuaternion& aOther) {
  74     *this = *this * aOther;
  75     return *this;
  76   }
  77
  78   mozilla::gfx::Matrix4x4 ToMatrix() const {
  79     mozilla::gfx::Matrix4x4 temp;
  80
  81     temp[0][0] = 1 - 2 * (y * y + z * z);
  82     temp[0][1] = 2 * (x * y + w * z);
  83     temp[0][2] = 2 * (x * z - w * y);
  84     temp[1][0] = 2 * (x * y - w * z);
  85     temp[1][1] = 1 - 2 * (x * x + z * z);
  86     temp[1][2] = 2 * (y * z + w * x);
  87     temp[2][0] = 2 * (x * z + w * y);
  88     temp[2][1] = 2 * (y * z - w * x);
  89     temp[2][2] = 1 - 2 * (x * x + y * y);
  90
  91     return temp;
  92   }
  93 };
  94
  95 #endif /* GFX_QUATERNION_H */