94 lines
3.3 KiB
C++
94 lines
3.3 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef GFX_QUATERNION_H
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#define GFX_QUATERNION_H
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#include "mozilla/gfx/BasePoint4D.h"
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#include "mozilla/gfx/Matrix.h"
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#include "nsAlgorithm.h"
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#include <algorithm>
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struct gfxQuaternion : public mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> {
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typedef mozilla::gfx::BasePoint4D<gfxFloat, gfxQuaternion> Super;
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gfxQuaternion() : Super() {}
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gfxQuaternion(gfxFloat aX, gfxFloat aY, gfxFloat aZ, gfxFloat aW) : Super(aX, aY, aZ, aW) {}
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explicit gfxQuaternion(const mozilla::gfx::Matrix4x4& aMatrix) {
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w = 0.5 * sqrt(std::max(1 + aMatrix[0][0] + aMatrix[1][1] + aMatrix[2][2], 0.0f));
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x = 0.5 * sqrt(std::max(1 + aMatrix[0][0] - aMatrix[1][1] - aMatrix[2][2], 0.0f));
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y = 0.5 * sqrt(std::max(1 - aMatrix[0][0] + aMatrix[1][1] - aMatrix[2][2], 0.0f));
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z = 0.5 * sqrt(std::max(1 - aMatrix[0][0] - aMatrix[1][1] + aMatrix[2][2], 0.0f));
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if(aMatrix[2][1] > aMatrix[1][2])
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x = -x;
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if(aMatrix[0][2] > aMatrix[2][0])
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y = -y;
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if(aMatrix[1][0] > aMatrix[0][1])
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z = -z;
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}
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// Convert from |direction axis, angle| pair to gfxQuaternion.
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//
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// Reference:
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// https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation
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//
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// if the direction axis is (x, y, z) = xi + yj + zk,
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// and the angle is |theta|, this formula can be done using
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// an extension of Euler's formula:
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// q = cos(theta/2) + (xi + yj + zk)(sin(theta/2))
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// = cos(theta/2) +
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// x*sin(theta/2)i + y*sin(theta/2)j + z*sin(theta/2)k
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// Note: aDirection should be an unit vector and
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// the unit of aAngle should be Radian.
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gfxQuaternion(const mozilla::gfx::Point3D &aDirection, gfxFloat aAngle) {
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MOZ_ASSERT(mozilla::gfx::FuzzyEqual(aDirection.Length(), 1.0f),
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"aDirection should be an unit vector");
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x = aDirection.x * sin(aAngle/2.0);
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y = aDirection.y * sin(aAngle/2.0);
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z = aDirection.z * sin(aAngle/2.0);
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w = cos(aAngle/2.0);
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}
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gfxQuaternion Slerp(const gfxQuaternion &aOther, gfxFloat aCoeff) {
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gfxFloat dot = mozilla::clamped(DotProduct(aOther), -1.0, 1.0);
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if (dot == 1.0) {
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return *this;
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}
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gfxFloat theta = acos(dot);
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gfxFloat rsintheta = 1/sqrt(1 - dot*dot);
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gfxFloat rightWeight = sin(aCoeff*theta)*rsintheta;
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gfxQuaternion left = *this;
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gfxQuaternion right = aOther;
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left *= cos(aCoeff*theta) - dot*rightWeight;
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right *= rightWeight;
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return left + right;
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}
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mozilla::gfx::Matrix4x4 ToMatrix() {
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mozilla::gfx::Matrix4x4 temp;
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temp[0][0] = 1 - 2 * (y * y + z * z);
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temp[0][1] = 2 * (x * y + w * z);
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temp[0][2] = 2 * (x * z - w * y);
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temp[1][0] = 2 * (x * y - w * z);
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temp[1][1] = 1 - 2 * (x * x + z * z);
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temp[1][2] = 2 * (y * z + w * x);
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temp[2][0] = 2 * (x * z + w * y);
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temp[2][1] = 2 * (y * z - w * x);
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temp[2][2] = 1 - 2 * (x * x + y * y);
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return temp;
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}
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};
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#endif /* GFX_QUATERNION_H */
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