IK_QSegment.cpp

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Original Author: Laurence
 * Contributor(s): Brecht
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include "IK_QSegment.h"
#include <cmath>

// Utility functions

static MT_Matrix3x3 RotationMatrix(MT_Scalar sine, MT_Scalar cosine, int axis)
{
    if (axis == 0)
        return MT_Matrix3x3(1.0, 0.0, 0.0,
                            0.0, cosine, -sine,
                            0.0, sine, cosine);
    else if (axis == 1)
        return MT_Matrix3x3(cosine, 0.0, sine,
                            0.0, 1.0, 0.0,
                            -sine, 0.0, cosine);
    else
        return MT_Matrix3x3(cosine, -sine, 0.0,
                            sine, cosine, 0.0,
                            0.0, 0.0, 1.0);
}

static MT_Matrix3x3 RotationMatrix(MT_Scalar angle, int axis)
{
    return RotationMatrix(sin(angle), cos(angle), axis);
}


static MT_Scalar EulerAngleFromMatrix(const MT_Matrix3x3& R, int axis)
{
    MT_Scalar t = sqrt(R[0][0]*R[0][0] + R[0][1]*R[0][1]);

    if (t > 16.0*MT_EPSILON) {
        if (axis == 0) return -atan2(R[1][2], R[2][2]);
        else if(axis == 1) return atan2(-R[0][2], t);
        else return -atan2(R[0][1], R[0][0]);
    } else {
        if (axis == 0) return -atan2(-R[2][1], R[1][1]);
        else if(axis == 1) return atan2(-R[0][2], t);
        else return 0.0f;
    }
}

static MT_Scalar safe_acos(MT_Scalar f)
{
    if (f <= -1.0f)
        return MT_PI;
    else if (f >= 1.0f)
        return 0.0;
    else
        return acos(f);
}

static MT_Scalar ComputeTwist(const MT_Matrix3x3& R)
{
    // qy and qw are the y and w components of the quaternion from R
    MT_Scalar qy = R[0][2] - R[2][0];
    MT_Scalar qw = R[0][0] + R[1][1] + R[2][2] + 1;

    MT_Scalar tau = 2*atan2(qy, qw);

    return tau;
}

static MT_Matrix3x3 ComputeTwistMatrix(MT_Scalar tau)
{
    return RotationMatrix(tau, 1);
}

static void RemoveTwist(MT_Matrix3x3& R)
{
    // compute twist parameter
    MT_Scalar tau = ComputeTwist(R);

    // compute twist matrix
    MT_Matrix3x3 T = ComputeTwistMatrix(tau);

    // remove twist
    R = R*T.transposed();
}

static MT_Vector3 SphericalRangeParameters(const MT_Matrix3x3& R)
{
    // compute twist parameter
    MT_Scalar tau = ComputeTwist(R);

    // compute swing parameters
    MT_Scalar num = 2.0*(1.0 + R[1][1]);

    // singularity at pi
    if (MT_abs(num) < MT_EPSILON)
        // TODO: this does now rotation of size pi over z axis, but could
        // be any axis, how to deal with this i'm not sure, maybe don't
        // enforce limits at all then
        return MT_Vector3(0.0, tau, 1.0);

    num = 1.0/sqrt(num);
    MT_Scalar ax = -R[2][1]*num;
    MT_Scalar az = R[0][1]*num;

    return MT_Vector3(ax, tau, az);
}

static MT_Matrix3x3 ComputeSwingMatrix(MT_Scalar ax, MT_Scalar az)
{
    // length of (ax, 0, az) = sin(theta/2)
    MT_Scalar sine2 = ax*ax + az*az;
    MT_Scalar cosine2 = sqrt((sine2 >= 1.0)? 0.0: 1.0-sine2);

    // compute swing matrix
    MT_Matrix3x3 S(MT_Quaternion(ax, 0.0, az, -cosine2));

    return S;
}

static MT_Vector3 MatrixToAxisAngle(const MT_Matrix3x3& R)
{
    MT_Vector3 delta = MT_Vector3(R[2][1] - R[1][2],
                                  R[0][2] - R[2][0],
                                  R[1][0] - R[0][1]);

    MT_Scalar c = safe_acos((R[0][0] + R[1][1] + R[2][2] - 1)/2);
    MT_Scalar l = delta.length();
    
    if (!MT_fuzzyZero(l))
        delta *= c/l;
    
    return delta;
}

static bool EllipseClamp(MT_Scalar& ax, MT_Scalar& az, MT_Scalar *amin, MT_Scalar *amax)
{
    MT_Scalar xlim, zlim, x, z;

    if (ax < 0.0) {
        x = -ax;
        xlim = -amin[0];
    }
    else {
        x = ax;
        xlim = amax[0];
    }

    if (az < 0.0) {
        z = -az;
        zlim = -amin[1];
    }
    else {
        z = az;
        zlim = amax[1];
    }

    if (MT_fuzzyZero(xlim) || MT_fuzzyZero(zlim)) {
        if (x <= xlim && z <= zlim)
            return false;

        if (x > xlim)
            x = xlim;
        if (z > zlim)
            z = zlim;
    }
    else {
        MT_Scalar invx = 1.0/(xlim*xlim);
        MT_Scalar invz = 1.0/(zlim*zlim);

        if ((x*x*invx + z*z*invz) <= 1.0)
            return false;

        if (MT_fuzzyZero(x)) {
            x = 0.0;
            z = zlim;
        }
        else {
            MT_Scalar rico = z/x;
            MT_Scalar old_x = x;
            x = sqrt(1.0/(invx + invz*rico*rico));
            if (old_x < 0.0)
                x = -x;
            z = rico*x;
        }
    }

    ax = (ax < 0.0)? -x: x;
    az = (az < 0.0)? -z: z;

    return true;
}

// IK_QSegment

IK_QSegment::IK_QSegment(int num_DoF, bool translational)
: m_parent(NULL), m_child(NULL), m_sibling(NULL), m_composite(NULL),
  m_num_DoF(num_DoF), m_translational(translational)
{
    m_locked[0] = m_locked[1] = m_locked[2] = false;
    m_weight[0] = m_weight[1] = m_weight[2] = 1.0;

    m_max_extension = 0.0;

    m_start = MT_Vector3(0, 0, 0);
    m_rest_basis.setIdentity();
    m_basis.setIdentity();
    m_translation = MT_Vector3(0, 0, 0);

    m_orig_basis = m_basis;
    m_orig_translation = m_translation;
}

void IK_QSegment::Reset()
{
    m_locked[0] = m_locked[1] = m_locked[2] = false;

    m_basis = m_orig_basis;
    m_translation = m_orig_translation;
    SetBasis(m_basis);

    for (IK_QSegment *seg = m_child; seg; seg = seg->m_sibling)
        seg->Reset();
}

void IK_QSegment::SetTransform(
    const MT_Vector3& start,
    const MT_Matrix3x3& rest_basis,
    const MT_Matrix3x3& basis,
    const MT_Scalar length
)
{
    m_max_extension = start.length() + length;  

    m_start = start;
    m_rest_basis = rest_basis;

    m_orig_basis = basis;
    SetBasis(basis);

    m_translation = MT_Vector3(0, length, 0);
    m_orig_translation = m_translation;
}

MT_Matrix3x3 IK_QSegment::BasisChange() const
{
    return m_orig_basis.transposed()*m_basis;
}

MT_Vector3 IK_QSegment::TranslationChange() const
{
    return m_translation - m_orig_translation;
}

IK_QSegment::~IK_QSegment()
{
    if (m_parent)
        m_parent->RemoveChild(this);

    for (IK_QSegment *seg = m_child; seg; seg = seg->m_sibling)
        seg->m_parent = NULL;
}

void IK_QSegment::SetParent(IK_QSegment *parent)
{
    if (m_parent == parent)
        return;
    
    if (m_parent)
        m_parent->RemoveChild(this);
    
    if (parent) {
        m_sibling = parent->m_child;
        parent->m_child = this;
    }

    m_parent = parent;
}

void IK_QSegment::SetComposite(IK_QSegment *seg)
{
    m_composite = seg;
}

void IK_QSegment::RemoveChild(IK_QSegment *child)
{
    if (m_child == NULL)
        return;
    else if (m_child == child)
        m_child = m_child->m_sibling;
    else {
        IK_QSegment *seg = m_child;

        while (seg->m_sibling != child)
            seg = seg->m_sibling;

        if (child == seg->m_sibling)
            seg->m_sibling = child->m_sibling;
    }
}

void IK_QSegment::UpdateTransform(const MT_Transform& global)
{
    // compute the global transform at the end of the segment
    m_global_start = global.getOrigin() + global.getBasis()*m_start;

    m_global_transform.setOrigin(m_global_start);
    m_global_transform.setBasis(global.getBasis() * m_rest_basis * m_basis);
    m_global_transform.translate(m_translation);

    // update child transforms
    for (IK_QSegment *seg = m_child; seg; seg = seg->m_sibling)
        seg->UpdateTransform(m_global_transform);
}

void IK_QSegment::PrependBasis(const MT_Matrix3x3& mat)
{
    m_basis = m_rest_basis.inverse() * mat * m_rest_basis * m_basis;
}

void IK_QSegment::Scale(float scale)
{
    m_start *= scale;
    m_translation *= scale;
    m_orig_translation *= scale;
    m_global_start *= scale;
    m_global_transform.getOrigin() *= scale;
    m_max_extension *= scale;
}

// IK_QSphericalSegment

IK_QSphericalSegment::IK_QSphericalSegment()
: IK_QSegment(3, false), m_limit_x(false), m_limit_y(false), m_limit_z(false)
{
}

MT_Vector3 IK_QSphericalSegment::Axis(int dof) const
{
    return m_global_transform.getBasis().getColumn(dof);
}

void IK_QSphericalSegment::SetLimit(int axis, MT_Scalar lmin, MT_Scalar lmax)
{
    if (lmin > lmax)
        return;
    
    if (axis == 1) {
        lmin = MT_clamp(lmin, -MT_PI, MT_PI);
        lmax = MT_clamp(lmax, -MT_PI, MT_PI);

        m_min_y = lmin;
        m_max_y = lmax;

        m_limit_y = true;
    }
    else {
        // clamp and convert to axis angle parameters
        lmin = MT_clamp(lmin, -MT_PI, MT_PI);
        lmax = MT_clamp(lmax, -MT_PI, MT_PI);

        lmin = sin(lmin*0.5);
        lmax = sin(lmax*0.5);

        if (axis == 0) {
            m_min[0] = -lmax;
            m_max[0] = -lmin;
            m_limit_x = true;
        }
        else if (axis == 2) {
            m_min[1] = -lmax;
            m_max[1] = -lmin;
            m_limit_z = true;
        }
    }
}

void IK_QSphericalSegment::SetWeight(int axis, MT_Scalar weight)
{
    m_weight[axis] = weight;
}

bool IK_QSphericalSegment::UpdateAngle(const IK_QJacobian &jacobian, MT_Vector3& delta, bool *clamp)
{
    if (m_locked[0] && m_locked[1] && m_locked[2])
        return false;

    MT_Vector3 dq;
    dq.x() = jacobian.AngleUpdate(m_DoF_id);
    dq.y() = jacobian.AngleUpdate(m_DoF_id+1);
    dq.z() = jacobian.AngleUpdate(m_DoF_id+2);

    // Directly update the rotation matrix, with Rodrigues' rotation formula,
    // to avoid singularities and allow smooth integration.

    MT_Scalar theta = dq.length();

    if (!MT_fuzzyZero(theta)) {
        MT_Vector3 w = dq*(1.0/theta);

        MT_Scalar sine = sin(theta);
        MT_Scalar cosine = cos(theta);
        MT_Scalar cosineInv = 1-cosine;

        MT_Scalar xsine = w.x()*sine;
        MT_Scalar ysine = w.y()*sine;
        MT_Scalar zsine = w.z()*sine;

        MT_Scalar xxcosine = w.x()*w.x()*cosineInv;
        MT_Scalar xycosine = w.x()*w.y()*cosineInv;
        MT_Scalar xzcosine = w.x()*w.z()*cosineInv;
        MT_Scalar yycosine = w.y()*w.y()*cosineInv;
        MT_Scalar yzcosine = w.y()*w.z()*cosineInv;
        MT_Scalar zzcosine = w.z()*w.z()*cosineInv;

        MT_Matrix3x3 M(
            cosine + xxcosine, -zsine + xycosine, ysine + xzcosine,
            zsine + xycosine, cosine + yycosine, -xsine + yzcosine,
            -ysine + xzcosine, xsine + yzcosine, cosine + zzcosine);

        m_new_basis = m_basis*M;
    }
    else
        m_new_basis = m_basis;

    
    if (m_limit_y == false && m_limit_x == false && m_limit_z == false)
        return false;

    MT_Vector3 a = SphericalRangeParameters(m_new_basis);

    if (m_locked[0])
        a.x() = m_locked_ax;
    if (m_locked[1])
        a.y() = m_locked_ay;
    if (m_locked[2])
        a.z() = m_locked_az;

    MT_Scalar ax = a.x(), ay = a.y(), az = a.z();

    clamp[0] = clamp[1] = clamp[2] =  false;
    
    if (m_limit_y) {
        if (a.y() > m_max_y) {
            ay = m_max_y;
            clamp[1] = true;
        }
        else if (a.y() < m_min_y) {
            ay = m_min_y;
            clamp[1] = true;
        }
    }

    if (m_limit_x && m_limit_z) {
        if (EllipseClamp(ax, az, m_min, m_max))
            clamp[0] = clamp[2] = true;
    }
    else if (m_limit_x) {
        if (ax < m_min[0]) {
            ax = m_min[0];
            clamp[0] = true;
        }
        else if (ax > m_max[0]) {
            ax = m_max[0];
            clamp[0] = true;
        }
    }
    else if (m_limit_z) {
        if (az < m_min[1]) {
            az = m_min[1];
            clamp[2] = true;
        }
        else if (az > m_max[1]) {
            az = m_max[1];
            clamp[2] = true;
        }
    }

    if (clamp[0] == false && clamp[1] == false && clamp[2] == false) {
        if (m_locked[0] || m_locked[1] || m_locked[2])
            m_new_basis = ComputeSwingMatrix(ax, az)*ComputeTwistMatrix(ay);
        return false;
    }
    
    m_new_basis = ComputeSwingMatrix(ax, az)*ComputeTwistMatrix(ay);

    delta = MatrixToAxisAngle(m_basis.transposed()*m_new_basis);

    if (!(m_locked[0] || m_locked[2]) && (clamp[0] || clamp[2])) {
        m_locked_ax = ax;
        m_locked_az = az;
    }

    if (!m_locked[1] && clamp[1])
        m_locked_ay = ay;
    
    return true;
}

void IK_QSphericalSegment::Lock(int dof, IK_QJacobian& jacobian, MT_Vector3& delta)
{
    if (dof == 1) {
        m_locked[1] = true;
        jacobian.Lock(m_DoF_id+1, delta[1]);
    }
    else {
        m_locked[0] = m_locked[2] = true;
        jacobian.Lock(m_DoF_id, delta[0]);
        jacobian.Lock(m_DoF_id+2, delta[2]);
    }
}

void IK_QSphericalSegment::UpdateAngleApply()
{
    m_basis = m_new_basis;
}

// IK_QNullSegment

IK_QNullSegment::IK_QNullSegment()
: IK_QSegment(0, false)
{
}

// IK_QRevoluteSegment

IK_QRevoluteSegment::IK_QRevoluteSegment(int axis)
: IK_QSegment(1, false), m_axis(axis), m_angle(0.0), m_limit(false)
{
}

void IK_QRevoluteSegment::SetBasis(const MT_Matrix3x3& basis)
{
    if (m_axis == 1) {
        m_angle = ComputeTwist(basis);
        m_basis = ComputeTwistMatrix(m_angle);
    }
    else {
        m_angle = EulerAngleFromMatrix(basis, m_axis);
        m_basis = RotationMatrix(m_angle, m_axis);
    }
}

MT_Vector3 IK_QRevoluteSegment::Axis(int) const
{
    return m_global_transform.getBasis().getColumn(m_axis);
}

bool IK_QRevoluteSegment::UpdateAngle(const IK_QJacobian &jacobian, MT_Vector3& delta, bool *clamp)
{
    if (m_locked[0])
        return false;

    m_new_angle = m_angle + jacobian.AngleUpdate(m_DoF_id);

    clamp[0] = false;

    if (m_limit == false)
        return false;

    if (m_new_angle > m_max)
        delta[0] = m_max - m_angle;
    else if (m_new_angle < m_min)
        delta[0] = m_min - m_angle;
    else
        return false;
    
    clamp[0] = true;
    m_new_angle = m_angle + delta[0];

    return true;
}

void IK_QRevoluteSegment::Lock(int, IK_QJacobian& jacobian, MT_Vector3& delta)
{
    m_locked[0] = true;
    jacobian.Lock(m_DoF_id, delta[0]);
}

void IK_QRevoluteSegment::UpdateAngleApply()
{
    m_angle = m_new_angle;
    m_basis = RotationMatrix(m_angle, m_axis);
}

void IK_QRevoluteSegment::SetLimit(int axis, MT_Scalar lmin, MT_Scalar lmax)
{
    if (lmin > lmax || m_axis != axis)
        return;
    
    // clamp and convert to axis angle parameters
    lmin = MT_clamp(lmin, -MT_PI, MT_PI);
    lmax = MT_clamp(lmax, -MT_PI, MT_PI);

    m_min = lmin;
    m_max = lmax;

    m_limit = true;
}

void IK_QRevoluteSegment::SetWeight(int axis, MT_Scalar weight)
{
    if (axis == m_axis)
        m_weight[0] = weight;
}

// IK_QSwingSegment

IK_QSwingSegment::IK_QSwingSegment()
: IK_QSegment(2, false), m_limit_x(false), m_limit_z(false)
{
}

void IK_QSwingSegment::SetBasis(const MT_Matrix3x3& basis)
{
    m_basis = basis;
    RemoveTwist(m_basis);
}

MT_Vector3 IK_QSwingSegment::Axis(int dof) const
{
    return m_global_transform.getBasis().getColumn((dof==0)? 0: 2);
}

bool IK_QSwingSegment::UpdateAngle(const IK_QJacobian &jacobian, MT_Vector3& delta, bool *clamp)
{
    if (m_locked[0] && m_locked[1])
        return false;

    MT_Vector3 dq;
    dq.x() = jacobian.AngleUpdate(m_DoF_id);
    dq.y() = 0.0;
    dq.z() = jacobian.AngleUpdate(m_DoF_id+1);

    // Directly update the rotation matrix, with Rodrigues' rotation formula,
    // to avoid singularities and allow smooth integration.

    MT_Scalar theta = dq.length();

    if (!MT_fuzzyZero(theta)) {
        MT_Vector3 w = dq*(1.0/theta);

        MT_Scalar sine = sin(theta);
        MT_Scalar cosine = cos(theta);
        MT_Scalar cosineInv = 1-cosine;

        MT_Scalar xsine = w.x()*sine;
        MT_Scalar zsine = w.z()*sine;

        MT_Scalar xxcosine = w.x()*w.x()*cosineInv;
        MT_Scalar xzcosine = w.x()*w.z()*cosineInv;
        MT_Scalar zzcosine = w.z()*w.z()*cosineInv;

        MT_Matrix3x3 M(
            cosine + xxcosine, -zsine, xzcosine,
            zsine, cosine, -xsine,
            xzcosine, xsine, cosine + zzcosine);

        m_new_basis = m_basis*M;

        RemoveTwist(m_new_basis);
    }
    else
        m_new_basis = m_basis;

    if (m_limit_x == false && m_limit_z == false)
        return false;

    MT_Vector3 a = SphericalRangeParameters(m_new_basis);
    MT_Scalar ax = 0, az = 0;

    clamp[0] = clamp[1] = false;
    
    if (m_limit_x && m_limit_z) {
        ax = a.x();
        az = a.z();

        if (EllipseClamp(ax, az, m_min, m_max))
            clamp[0] = clamp[1] = true;
    }
    else if (m_limit_x) {
        if (ax < m_min[0]) {
            ax = m_min[0];
            clamp[0] = true;
        }
        else if (ax > m_max[0]) {
            ax = m_max[0];
            clamp[0] = true;
        }
    }
    else if (m_limit_z) {
        if (az < m_min[1]) {
            az = m_min[1];
            clamp[1] = true;
        }
        else if (az > m_max[1]) {
            az = m_max[1];
            clamp[1] = true;
        }
    }

    if (clamp[0] == false && clamp[1] == false)
        return false;

    m_new_basis = ComputeSwingMatrix(ax, az);

    delta = MatrixToAxisAngle(m_basis.transposed()*m_new_basis);
    delta[1] = delta[2]; delta[2] = 0.0;

    return true;
}

void IK_QSwingSegment::Lock(int, IK_QJacobian& jacobian, MT_Vector3& delta)
{
    m_locked[0] = m_locked[1] = true;
    jacobian.Lock(m_DoF_id, delta[0]);
    jacobian.Lock(m_DoF_id+1, delta[1]);
}

void IK_QSwingSegment::UpdateAngleApply()
{
    m_basis = m_new_basis;
}

void IK_QSwingSegment::SetLimit(int axis, MT_Scalar lmin, MT_Scalar lmax)
{
    if (lmin > lmax)
        return;
    
    // clamp and convert to axis angle parameters
    lmin = MT_clamp(lmin, -MT_PI, MT_PI);
    lmax = MT_clamp(lmax, -MT_PI, MT_PI);

    lmin = sin(lmin*0.5);
    lmax = sin(lmax*0.5);

    // put center of ellispe in the middle between min and max
    MT_Scalar offset = 0.5*(lmin + lmax);
    //lmax = lmax - offset;

    if (axis == 0) {
        m_min[0] = -lmax;
        m_max[0] = -lmin;

        m_limit_x = true;
        m_offset_x = offset;
        m_max_x = lmax;
    }
    else if (axis == 2) {
        m_min[1] = -lmax;
        m_max[1] = -lmin;

        m_limit_z = true;
        m_offset_z = offset;
        m_max_z = lmax;
    }
}

void IK_QSwingSegment::SetWeight(int axis, MT_Scalar weight)
{
    if (axis == 0)
        m_weight[0] = weight;
    else if (axis == 2)
        m_weight[1] = weight;
}

// IK_QElbowSegment

IK_QElbowSegment::IK_QElbowSegment(int axis)
: IK_QSegment(2, false), m_axis(axis), m_twist(0.0), m_angle(0.0),
  m_cos_twist(1.0), m_sin_twist(0.0), m_limit(false), m_limit_twist(false)
{
}

void IK_QElbowSegment::SetBasis(const MT_Matrix3x3& basis)
{
    m_basis = basis;

    m_twist = ComputeTwist(m_basis);
    RemoveTwist(m_basis);
    m_angle = EulerAngleFromMatrix(basis, m_axis);

    m_basis = RotationMatrix(m_angle, m_axis)*ComputeTwistMatrix(m_twist);
}

MT_Vector3 IK_QElbowSegment::Axis(int dof) const
{
    if (dof == 0) {
        MT_Vector3 v;
        if (m_axis == 0)
            v = MT_Vector3(m_cos_twist, 0, m_sin_twist);
        else
            v = MT_Vector3(-m_sin_twist, 0, m_cos_twist);

        return m_global_transform.getBasis() * v;
    }
    else
        return m_global_transform.getBasis().getColumn(1);
}

bool IK_QElbowSegment::UpdateAngle(const IK_QJacobian &jacobian, MT_Vector3& delta, bool *clamp)
{
    if (m_locked[0] && m_locked[1])
        return false;

    clamp[0] = clamp[1] = false;

    if (!m_locked[0]) {
        m_new_angle = m_angle + jacobian.AngleUpdate(m_DoF_id);

        if (m_limit) {
            if (m_new_angle > m_max) {
                delta[0] = m_max - m_angle;
                m_new_angle = m_max;
                clamp[0] = true;
            }
            else if (m_new_angle < m_min) {
                delta[0] = m_min - m_angle;
                m_new_angle = m_min;
                clamp[0] = true;
            }
        }
    }

    if (!m_locked[1]) {
        m_new_twist = m_twist + jacobian.AngleUpdate(m_DoF_id+1);

        if (m_limit_twist) {
            if (m_new_twist > m_max_twist) {
                delta[1] = m_max_twist - m_twist;
                m_new_twist = m_max_twist;
                clamp[1] = true;
            }
            else if (m_new_twist < m_min_twist) {
                delta[1] = m_min_twist - m_twist;
                m_new_twist = m_min_twist;
                clamp[1] = true;
            }
        }
    }

    return (clamp[0] || clamp[1]);
}

void IK_QElbowSegment::Lock(int dof, IK_QJacobian& jacobian, MT_Vector3& delta)
{
    if (dof == 0) {
        m_locked[0] = true;
        jacobian.Lock(m_DoF_id, delta[0]);
    }
    else {
        m_locked[1] = true;
        jacobian.Lock(m_DoF_id+1, delta[1]);
    }
}

void IK_QElbowSegment::UpdateAngleApply()
{
    m_angle = m_new_angle;
    m_twist = m_new_twist;

    m_sin_twist = sin(m_twist);
    m_cos_twist = cos(m_twist);

    MT_Matrix3x3 A = RotationMatrix(m_angle, m_axis);
    MT_Matrix3x3 T = RotationMatrix(m_sin_twist, m_cos_twist, 1);

    m_basis = A*T;
}

void IK_QElbowSegment::SetLimit(int axis, MT_Scalar lmin, MT_Scalar lmax)
{
    if (lmin > lmax)
        return;

    // clamp and convert to axis angle parameters
    lmin = MT_clamp(lmin, -MT_PI, MT_PI);
    lmax = MT_clamp(lmax, -MT_PI, MT_PI);

    if (axis == 1) {
        m_min_twist = lmin;
        m_max_twist = lmax;
        m_limit_twist = true;
    }
    else if (axis == m_axis) {
        m_min = lmin;
        m_max = lmax;
        m_limit = true;
    }
}

void IK_QElbowSegment::SetWeight(int axis, MT_Scalar weight)
{
    if (axis == m_axis)
        m_weight[0] = weight;
    else if (axis == 1)
        m_weight[1] = weight;
}

// IK_QTranslateSegment

IK_QTranslateSegment::IK_QTranslateSegment(int axis1)
: IK_QSegment(1, true)
{
    m_axis_enabled[0] = m_axis_enabled[1] = m_axis_enabled[2] = false;
    m_axis_enabled[axis1] = true;

    m_axis[0] = axis1;

    m_limit[0] = m_limit[1] = m_limit[2] = false;
}

IK_QTranslateSegment::IK_QTranslateSegment(int axis1, int axis2)
: IK_QSegment(2, true)
{
    m_axis_enabled[0] = m_axis_enabled[1] = m_axis_enabled[2] = false;
    m_axis_enabled[axis1] = true;
    m_axis_enabled[axis2] = true;

    m_axis[0] = axis1;
    m_axis[1] = axis2;

    m_limit[0] = m_limit[1] = m_limit[2] = false;
}

IK_QTranslateSegment::IK_QTranslateSegment()
: IK_QSegment(3, true)
{
    m_axis_enabled[0] = m_axis_enabled[1] = m_axis_enabled[2] = true;

    m_axis[0] = 0;
    m_axis[1] = 1;
    m_axis[2] = 2;

    m_limit[0] = m_limit[1] = m_limit[2] = false;
}

MT_Vector3 IK_QTranslateSegment::Axis(int dof) const
{
    return m_global_transform.getBasis().getColumn(m_axis[dof]);
}

bool IK_QTranslateSegment::UpdateAngle(const IK_QJacobian &jacobian, MT_Vector3& delta, bool *clamp)
{
    int dof_id = m_DoF_id, dof = 0, i, clamped = false;

    MT_Vector3 dx(0.0, 0.0, 0.0);

    for (i = 0; i < 3; i++) {
        if (!m_axis_enabled[i]) {
            m_new_translation[i] = m_translation[i];
            continue;
        }

        clamp[dof] = false;

        if (!m_locked[dof]) {
            m_new_translation[i] = m_translation[i] + jacobian.AngleUpdate(dof_id);

            if (m_limit[i]) {
                if (m_new_translation[i] > m_max[i]) {
                    delta[dof] = m_max[i] - m_translation[i];
                    m_new_translation[i] = m_max[i];
                    clamped = clamp[dof] = true;
                }
                else if (m_new_translation[i] < m_min[i]) {
                    delta[dof] = m_min[i] - m_translation[i];
                    m_new_translation[i] = m_min[i];
                    clamped = clamp[dof] = true;
                }
            }
        }

        dof_id++;
        dof++;
    }

    return clamped;
}

void IK_QTranslateSegment::UpdateAngleApply()
{
    m_translation = m_new_translation;
}

void IK_QTranslateSegment::Lock(int dof, IK_QJacobian& jacobian, MT_Vector3& delta)
{
    m_locked[dof] = true;
    jacobian.Lock(m_DoF_id+dof, delta[dof]);
}

void IK_QTranslateSegment::SetWeight(int axis, MT_Scalar weight)
{
    int i;

    for (i = 0; i < m_num_DoF; i++)
        if (m_axis[i] == axis)
            m_weight[i] = weight;
}

void IK_QTranslateSegment::SetLimit(int axis, MT_Scalar lmin, MT_Scalar lmax)
{
    if (lmax < lmin)
        return;

    m_min[axis]= lmin;
    m_max[axis]= lmax;
    m_limit[axis]= true;
}

void IK_QTranslateSegment::Scale(float scale)
{
    int i;

    IK_QSegment::Scale(scale);

    for (i = 0; i < 3; i++) {
        m_min[0] *= scale;
        m_max[1] *= scale;
    }

    m_new_translation *= scale;
}