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/****************************************************************************
**
** Copyright (C) 2008-2012 NVIDIA Corporation.
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt 3D Studio.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#pragma once
#ifndef QT3DS_RENDER_ROTATION_HELPER_H
#define QT3DS_RENDER_ROTATION_HELPER_H
#include "Qt3DSRender.h"
#include "Qt3DSRenderNode.h"
#include "EASTL/utility.h"
namespace qt3ds {
namespace render {
/**
* Unfortunately we still use an XYZ-Euler rotation system. This means that identical
*rotations
* can be represented in various ways. We need to ensure that the value that we write in the
* inspector palette are reasonable, however, and to do this we need a least-distance function
* from two different xyz tuples.
*/
struct SRotationHelper
{
// Attempt to go for negative values intead of large positive ones
// Goal is to keep the fabs of the angle low.
static QT3DSF32 ToMinimalAngle(QT3DSF32 value)
{
QT3DSF32 epsilon = (QT3DSF32)M_PI + .001f;
while (fabs(value) > epsilon) {
QT3DSF32 tpi = (QT3DSF32)(2.0f * M_PI);
if (value > 0.0f)
value -= tpi;
else
value += tpi;
}
return value;
}
/**
* Convert an angle to a canonical form. Return this canonical form.
*
* The canonical form is defined as:
* 1. XYZ all positive.
* 2. XYZ all less than 360.
*
* To do this we rely on two identities, the first is that given an angle, adding
* (or subtracting) pi from all three components does not change the angle.
*
* The second is the obvious one that adding or subtracting 2*pi from any single
* component does not change the angle.
*
* Note that this function works in radian space.
*/
static QT3DSVec3 ToCanonicalFormStaticAxis(const QT3DSVec3 &inSrcAngle, QT3DSU32 inRotOrder)
{
// step 1 - reduce all components to less than 2*pi but greater than 0
QT3DSVec3 retval(inSrcAngle);
retval.x = ToMinimalAngle(retval.x);
retval.y = ToMinimalAngle(retval.y);
retval.z = ToMinimalAngle(retval.z);
// step 2 - if any two components are equal to or greater than pi
// then subtract pi from all three, then run two pi reduce again.
QT3DSU32 greaterThanPiSum = 0;
QT3DSF32 pi = (QT3DSF32)M_PI;
for (QT3DSU32 idx = 0; idx < 3; ++idx)
if (fabs(retval[idx]) >= pi)
greaterThanPiSum++;
if (greaterThanPiSum > 1) {
// For this identity to work, the middle axis angle needs to be subtracted from
// 180 instead of added to 180 because the previous axis *reversed* it.
QT3DSU32 theMiddleAxis = 0;
switch (inRotOrder) {
case EulOrdXYZs:
theMiddleAxis = 1;
break;
case EulOrdXZYs:
theMiddleAxis = 2;
break;
case EulOrdYXZs:
theMiddleAxis = 0;
break;
case EulOrdYZXs:
theMiddleAxis = 2;
break;
case EulOrdZYXs:
theMiddleAxis = 1;
break;
case EulOrdZXYs:
theMiddleAxis = 0;
break;
case EulOrdXYZr:
theMiddleAxis = 1;
break;
case EulOrdXZYr:
theMiddleAxis = 2;
break;
case EulOrdYXZr:
theMiddleAxis = 0;
break;
case EulOrdYZXr:
theMiddleAxis = 2;
break;
case EulOrdZYXr:
theMiddleAxis = 1;
break;
case EulOrdZXYr:
theMiddleAxis = 0;
break;
default:
QT3DS_ASSERT(false);
return inSrcAngle;
}
for (QT3DSU32 idx = 0; idx < 3; ++idx) {
if (idx == theMiddleAxis)
retval[idx] = pi - retval[idx];
else
retval[idx] = retval[idx] > 0.0f ? retval[idx] - pi : retval[idx] + pi;
}
}
return retval;
}
static QT3DSVec3 ToMinimalAngleDiff(const QT3DSVec3 inDiff)
{
return QT3DSVec3(ToMinimalAngle(inDiff.x), ToMinimalAngle(inDiff.y),
ToMinimalAngle(inDiff.z));
}
/**
* Given an old angle and a new angle, return an angle has the same rotational value
* as the new angle *but* is as close to the old angle as possible.
* Works in radian space. This function doesn't currently work for euler angles or
* with Euler angles with repeating axis.
*/
static QT3DSVec3 ToNearestAngle(const QT3DSVec3 &inOldAngle, const QT3DSVec3 &inNewAngle,
QT3DSU32 inRotOrder)
{
switch (inRotOrder) {
case EulOrdXYZs:
case EulOrdXZYs:
case EulOrdYXZs:
case EulOrdYZXs:
case EulOrdZYXs:
case EulOrdZXYs:
case EulOrdXYZr:
case EulOrdXZYr:
case EulOrdYXZr:
case EulOrdYZXr:
case EulOrdZYXr:
case EulOrdZXYr: {
QT3DSVec3 oldA = ToCanonicalFormStaticAxis(inOldAngle, inRotOrder);
QT3DSVec3 newA = ToCanonicalFormStaticAxis(inNewAngle, inRotOrder);
QT3DSVec3 diff = newA - oldA;
return inOldAngle + ToMinimalAngleDiff(diff);
} break;
default:
return inNewAngle;
}
}
};
}
}
#endif
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