flutter_flutter/sky/engine/platform/transforms/RotateTransformOperation.cpp

/*
 * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "flutter/sky/engine/platform/transforms/RotateTransformOperation.h"

#include <algorithm>
#include "flutter/sky/engine/platform/animation/AnimationUtilities.h"
#include "flutter/sky/engine/platform/geometry/FloatPoint3D.h"
#include "flutter/sky/engine/wtf/MathExtras.h"

namespace blink {

static const double angleEpsilon = 1e-4;

FloatPoint3D RotateTransformOperation::axis() const
{
    return FloatPoint3D(x(), y(), z());
}

bool RotateTransformOperation::shareSameAxis(const RotateTransformOperation* from, const RotateTransformOperation* to, FloatPoint3D* axis, double* fromAngle, double* toAngle)
{
    *axis = FloatPoint3D(0, 0, 1);
    *fromAngle = 0;
    *toAngle = 0;

    if (!from && !to)
        return true;

    bool fromZero = !from || from->axis().isZero();
    bool toZero = !to || to->axis().isZero();

    if (fromZero && toZero)
        return true;

    if (fromZero) {
        *axis = to->axis();
        *toAngle = to->angle();
        return true;
    }

    if (toZero) {
        *axis = from->axis();
        *fromAngle = from->angle();
        return true;
    }

    FloatPoint3D fromAxis = from->axis();
    FloatPoint3D toAxis = to->axis();

    double fromSquared = fromAxis.lengthSquared();
    double toSquared   = toAxis.lengthSquared();

    double dot = fromAxis.dot(toAxis);
    double error = std::abs(1 - (dot * dot) / (fromSquared * toSquared));

    if (error > angleEpsilon)
        return false;
    *axis = from->axis();
    *fromAngle = from->angle();
    *toAngle = to->angle();
    return true;
}

PassRefPtr<TransformOperation> RotateTransformOperation::blend(const TransformOperation* from, double progress, bool blendToIdentity)
{
    if (from && !from->isSameType(*this))
        return this;

    if (blendToIdentity)
        return RotateTransformOperation::create(m_x, m_y, m_z, m_angle - m_angle * progress, m_type);

    const RotateTransformOperation* fromOp = static_cast<const RotateTransformOperation*>(from);

    // Optimize for single axis rotation
    if (!fromOp || (fromOp->m_x == 0 && fromOp->m_y == 0 && fromOp->m_z == 1) ||
                   (fromOp->m_x == 0 && fromOp->m_y == 1 && fromOp->m_z == 0) ||
                   (fromOp->m_x == 1 && fromOp->m_y == 0 && fromOp->m_z == 0)) {
        double fromAngle = fromOp ? fromOp->m_angle : 0;
        return RotateTransformOperation::create(fromOp ? fromOp->m_x : m_x,
                                                fromOp ? fromOp->m_y : m_y,
                                                fromOp ? fromOp->m_z : m_z,
                                                blink::blend(fromAngle, m_angle, progress), m_type);
    }
    double fromAngle;
    double toAngle;
    FloatPoint3D axis;

    if (shareSameAxis(fromOp, this, &axis, &fromAngle, &toAngle))
        return RotateTransformOperation::create(axis.x(), axis.y(), axis.z(), blink::blend(fromAngle, toAngle, progress), m_type);

    const RotateTransformOperation* toOp = this;

    // Create the 2 rotation matrices
    TransformationMatrix fromT;
    TransformationMatrix toT;
    fromT.rotate3d((fromOp ? fromOp->m_x : 0),
        (fromOp ? fromOp->m_y : 0),
        (fromOp ? fromOp->m_z : 1),
        (fromOp ? fromOp->m_angle : 0));

    toT.rotate3d((toOp ? toOp->m_x : 0),
        (toOp ? toOp->m_y : 0),
        (toOp ? toOp->m_z : 1),
        (toOp ? toOp->m_angle : 0));

    // Blend them
    toT.blend(fromT, progress);

    // Extract the result as a quaternion
    TransformationMatrix::DecomposedType decomp;
    toT.decompose(decomp);

    // Convert that to Axis/Angle form
    double x = -decomp.quaternionX;
    double y = -decomp.quaternionY;
    double z = -decomp.quaternionZ;
    double length = std::sqrt(x * x + y * y + z * z);
    double angle = 0;

    if (length > 0.00001) {
        x /= length;
        y /= length;
        z /= length;
        angle = rad2deg(std::acos(decomp.quaternionW) * 2);
    } else {
        x = 0;
        y = 0;
        z = 1;
    }
    return RotateTransformOperation::create(x, y, z, angle, Rotate3D);
}

bool RotateTransformOperation::canBlendWith(const TransformOperation& other) const
{
    return other.isSameType(*this);
}

} // namespace blink