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+/*************************************************************************
+ * *
+ * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith. *
+ * All rights reserved. Email: russ@q12.org Web: www.q12.org *
+ * *
+ * This library is free software; you can redistribute it and/or *
+ * modify it under the terms of EITHER: *
+ * (1) The GNU Lesser General Public License as published by the Free *
+ * Software Foundation; either version 2.1 of the License, or (at *
+ * your option) any later version. The text of the GNU Lesser *
+ * General Public License is included with this library in the *
+ * file LICENSE.TXT. *
+ * (2) The BSD-style license that is included with this library in *
+ * the file LICENSE-BSD.TXT. *
+ * *
+ * 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 files *
+ * LICENSE.TXT and LICENSE-BSD.TXT for more details. *
+ * *
+ *************************************************************************/
+
+
+#include <ode/odeconfig.h>
+#include "config.h"
+#include "transmission.h"
+#include "joint_internal.h"
+
+namespace {
+ static inline dReal clamp(dReal x, dReal minX, dReal maxX)
+ {
+ return x < minX ? minX : (x > maxX ? maxX : x);
+ }
+}
+
+/*
+ * Transmission joint
+ */
+
+dxJointTransmission::dxJointTransmission(dxWorld* w) :
+ dxJoint(w)
+{
+ int i;
+
+ flags |= dJOINT_TWOBODIES;
+ mode = dTransmissionParallelAxes;
+
+ cfm = world->global_cfm;
+ erp = world->global_erp;
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dSetZero( anchors[i], 4 );
+ dSetZero( axes[i], 4 );
+ axes[i][0] = 1;
+
+ radii[i] = 0;
+ }
+
+ backlash = 0;
+ ratio = 1;
+ update = 1;
+}
+
+void
+dxJointTransmission::getSureMaxInfo( SureMaxInfo* info )
+{
+ info->max_m = 1;
+}
+
+void
+dxJointTransmission::getInfo1( dxJoint::Info1* info )
+{
+ // If there's backlash in the gears then constraint must be
+ // unilateral, that is the driving gear can only push the driven
+ // gear in one direction. In order to push it in the other it
+ // first needs to traverse the backlash gap.
+
+ info->m = 1;
+ info->nub = backlash > 0 ? 0 : 1;
+}
+
+void
+dxJointTransmission::getInfo2( dReal worldFPS, dReal /*worldERP*/,
+ int rowskip, dReal *J1, dReal *J2,
+ int pairskip, dReal *pairRhsCfm, dReal *pairLoHi,
+ int *findex )
+ {
+ dVector3 a[2], n[2], l[2], r[2], c[2], s, t, O, d, z, u, v;
+ dReal theta, delta, nn, na_0, na_1, cosphi, sinphi, m;
+ const dReal *p[2], *omega[2];
+ int i;
+
+ // Transform all needed quantities to the global frame.
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dBodyGetRelPointPos(node[i].body,
+ anchors[i][0], anchors[i][1], anchors[i][2],
+ a[i]);
+
+ dBodyVectorToWorld(node[i].body, axes[i][0], axes[i][1], axes[i][2],
+ n[i]);
+
+ p[i] = dBodyGetPosition(node[i].body);
+ omega[i] = dBodyGetAngularVel(node[i].body);
+ }
+
+ if (update) {
+ // Make sure both gear reference frames end up with the same
+ // handedness.
+
+ if (dCalcVectorDot3(n[0], n[1]) < 0) {
+ dNegateVector3(axes[0]);
+ dNegateVector3(n[0]);
+ }
+ }
+
+ // Calculate the mesh geometry based on the current mode.
+
+ switch (mode) {
+ case dTransmissionParallelAxes:
+ // Simply calculate the contact point as the point on the
+ // baseline that will yield the correct ratio.
+
+ dIASSERT (ratio > 0);
+
+ dSubtractVectors3(d, a[1], a[0]);
+ dAddVectorScaledVector3(c[0], a[0], d, ratio / (1 + ratio));
+ dCopyVector3(c[1], c[0]);
+
+ dNormalize3(d);
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dCalcVectorCross3(l[i], d, n[i]);
+ }
+
+ break;
+ case dTransmissionIntersectingAxes:
+ // Calculate the line of intersection between the planes of the
+ // gears.
+
+ dCalcVectorCross3(l[0], n[0], n[1]);
+ dCopyVector3(l[1], l[0]);
+
+ nn = dCalcVectorDot3(n[0], n[1]);
+ dIASSERT(fabs(nn) != 1);
+
+ na_0 = dCalcVectorDot3(n[0], a[0]);
+ na_1 = dCalcVectorDot3(n[1], a[1]);
+
+ dAddScaledVectors3(O, n[0], n[1],
+ (na_0 - na_1 * nn) / (1 - nn * nn),
+ (na_1 - na_0 * nn) / (1 - nn * nn));
+
+ // Find the contact point as:
+ //
+ // c = ((r_a - O) . l) l + O
+ //
+ // where r_a the anchor point of either gear and l, O the tangent
+ // line direction and origin.
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dSubtractVectors3(d, a[i], O);
+ m = dCalcVectorDot3(d, l[i]);
+ dAddVectorScaledVector3(c[i], O, l[i], m);
+ }
+
+ break;
+ case dTransmissionChainDrive:
+ dSubtractVectors3(d, a[0], a[1]);
+ m = dCalcVectorLength3(d);
+
+ dIASSERT(m > 0);
+
+ // Caclulate the angle of the contact point relative to the
+ // baseline.
+
+ cosphi = clamp((radii[1] - radii[0]) / m, REAL(-1.0), REAL(1.0)); // Force into range to fix possible computation errors
+ sinphi = dSqrt (REAL(1.0) - cosphi * cosphi);
+
+ dNormalize3(d);
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ // Calculate the contact radius in the local reference
+ // frame of the chain. This has axis x pointing along the
+ // baseline, axis y pointing along the sprocket axis and
+ // the remaining axis normal to both.
+
+ u[0] = radii[i] * cosphi;
+ u[1] = 0;
+ u[2] = radii[i] * sinphi;
+
+ // Transform the contact radius into the global frame.
+
+ dCalcVectorCross3(z, d, n[i]);
+
+ v[0] = dCalcVectorDot3(d, u);
+ v[1] = dCalcVectorDot3(n[i], u);
+ v[2] = dCalcVectorDot3(z, u);
+
+ // Finally calculate contact points and l.
+
+ dAddVectors3(c[i], a[i], v);
+ dCalcVectorCross3(l[i], v, n[i]);
+ dNormalize3(l[i]);
+
+ // printf ("%d: %f, %f, %f\n",
+ // i, l[i][0], l[i][1], l[i][2]);
+ }
+
+ break;
+ }
+
+ if (update) {
+ // We need to calculate an initial reference frame for each
+ // wheel which we can measure the current phase against. This
+ // frame will have the initial contact radius as the x axis,
+ // the wheel axis as the z axis and their cross product as the
+ // y axis.
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dSubtractVectors3 (r[i], c[i], a[i]);
+ radii[i] = dCalcVectorLength3(r[i]);
+ dIASSERT(radii[i] > 0);
+
+ dBodyVectorFromWorld(node[i].body, r[i][0], r[i][1], r[i][2],
+ reference[i]);
+ dNormalize3(reference[i]);
+ dCopyVector3(reference[i] + 8, axes[i]);
+ dCalcVectorCross3(reference[i] + 4, reference[i] + 8, reference[i]);
+
+ // printf ("%f\n", dDOT(r[i], n[i]));
+ // printf ("(%f, %f, %f,\n %f, %f, %f,\n %f, %f, %f)\n",
+ // reference[i][0],reference[i][1],reference[i][2],
+ // reference[i][4],reference[i][5],reference[i][6],
+ // reference[i][8],reference[i][9],reference[i][10]);
+
+ phase[i] = 0;
+ }
+
+ ratio = radii[0] / radii[1];
+ update = 0;
+ }
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dReal phase_hat;
+
+ dSubtractVectors3 (r[i], c[i], a[i]);
+
+ // Transform the (global) contact radius into the gear's
+ // reference frame.
+
+ dBodyVectorFromWorld (node[i].body, r[i][0], r[i][1], r[i][2], s);
+ dMultiply0_331(t, reference[i], s);
+
+ // Now simply calculate its angle on the plane relative to the
+ // x-axis which is the initial contact radius. This will be
+ // an angle between -pi and pi that is coterminal with the
+ // actual phase of the wheel. To find the real phase we
+ // estimate it by adding omega * dt to the old phase and then
+ // find the closest angle to that, that is coterminal to
+ // theta.
+
+ theta = atan2(t[1], t[0]);
+ phase_hat = phase[i] + dCalcVectorDot3(omega[i], n[i]) / worldFPS;
+
+ if (phase_hat > M_PI_2) {
+ if (theta < 0) {
+ theta += (dReal)(2 * M_PI);
+ }
+
+ theta += (dReal)(floor(phase_hat / (2 * M_PI)) * (2 * M_PI));
+ } else if (phase_hat < -M_PI_2) {
+ if (theta > 0) {
+ theta -= (dReal)(2 * M_PI);
+ }
+
+ theta += (dReal)(ceil(phase_hat / (2 * M_PI)) * (2 * M_PI));
+ }
+
+ if (phase_hat - theta > M_PI) {
+ phase[i] = theta + (dReal)(2 * M_PI);
+ } else if (phase_hat - theta < -M_PI) {
+ phase[i] = theta - (dReal)(2 * M_PI);
+ } else {
+ phase[i] = theta;
+ }
+
+ dIASSERT(fabs(phase_hat - phase[i]) < M_PI);
+ }
+
+ // Calculate the phase error. Depending on the mode the condition
+ // is that the distances traveled by each contact point must be
+ // either equal (chain and sprockets) or opposite (gears).
+
+ if (mode == dTransmissionChainDrive) {
+ delta = (dCalcVectorLength3(r[0]) * phase[0] -
+ dCalcVectorLength3(r[1]) * phase[1]);
+ } else {
+ delta = (dCalcVectorLength3(r[0]) * phase[0] +
+ dCalcVectorLength3(r[1]) * phase[1]);
+ }
+
+ // When in chain mode a torque reversal, signified by the change
+ // in sign of the wheel phase difference, has the added effect of
+ // switching the active chain branch. We must therefore reflect
+ // the contact points and tangents across the baseline.
+
+ if (mode == dTransmissionChainDrive && delta < 0) {
+ dVector3 d;
+
+ dSubtractVectors3(d, a[0], a[1]);
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dVector3 nn;
+ dReal a;
+
+ dCalcVectorCross3(nn, n[i], d);
+ a = dCalcVectorDot3(nn, nn);
+ dIASSERT(a > 0);
+
+ dAddScaledVectors3(c[i], c[i], nn,
+ 1, -2 * dCalcVectorDot3(c[i], nn) / a);
+ dAddScaledVectors3(l[i], l[i], nn,
+ -1, 2 * dCalcVectorDot3(l[i], nn) / a);
+ }
+ }
+
+ // Do not add the constraint if there's backlash and we're in the
+ // backlash gap.
+
+ if (backlash == 0 || fabs(delta) > backlash) {
+ // The constraint is satisfied if the absolute velocity of the
+ // contact point projected onto the tangent of the wheels is equal
+ // for both gears. This velocity can be calculated as:
+ //
+ // u = v + omega x r_c
+ //
+ // The constraint therefore becomes:
+ // (v_1 + omega_1 x r_c1) . l = (v_2 + omega_2 x r_c2) . l <=>
+ // (v_1 . l + (r_c1 x l) . omega_1 = v_2 . l + (r_c2 x l) . omega_2
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ dSubtractVectors3 (r[i], c[i], p[i]);
+ }
+
+ dCopyVector3(J1 + GI2__JL_MIN, l[0]);
+ dCalcVectorCross3(J1 + GI2__JA_MIN, r[0], l[0]);
+
+ dCopyNegatedVector3(J2 + GI2__JL_MIN, l[1]);
+ dCalcVectorCross3(J2 + GI2__JA_MIN, l[1], r[1]);
+
+ if (delta > 0) {
+ if (backlash > 0) {
+ pairLoHi[GI2_LO] = -dInfinity;
+ pairLoHi[GI2_HI] = 0;
+ }
+
+ pairRhsCfm[GI2_RHS] = -worldFPS * erp * (delta - backlash);
+ } else {
+ if (backlash > 0) {
+ pairLoHi[GI2_LO] = 0;
+ pairLoHi[GI2_HI] = dInfinity;
+ }
+
+ pairRhsCfm[GI2_RHS] = -worldFPS * erp * (delta + backlash);
+ }
+ }
+
+ pairRhsCfm[GI2_CFM] = cfm;
+
+ // printf ("%f, %f, %f, %f, %f\n", delta, phase[0], phase[1], -phase[1] / phase[0], ratio);
+
+ // Cache the contact point (in world coordinates) to avoid
+ // recalculation if requested by the user.
+
+ dCopyVector3(contacts[0], c[0]);
+ dCopyVector3(contacts[1], c[1]);
+}
+
+void dJointSetTransmissionAxis( dJointID j, dReal x, dReal y, dReal z )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ int i;
+
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT(joint->mode == dTransmissionParallelAxes ||
+ joint->mode == dTransmissionChainDrive ,
+ "axes must be set individualy in current mode" );
+
+ for (i = 0 ; i < 2 ; i += 1) {
+ if (joint->node[i].body) {
+ dBodyVectorFromWorld(joint->node[i].body, x, y, z, joint->axes[i]);
+ dNormalize3(joint->axes[i]);
+ }
+ }
+
+ joint->update = 1;
+}
+
+void dJointSetTransmissionAxis1( dJointID j, dReal x, dReal y, dReal z )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT(joint->mode == dTransmissionIntersectingAxes,
+ "can't set individual axes in current mode" );
+
+ if (joint->node[0].body) {
+ dBodyVectorFromWorld(joint->node[0].body, x, y, z, joint->axes[0]);
+ dNormalize3(joint->axes[0]);
+ }
+
+ joint->update = 1;
+}
+
+void dJointSetTransmissionAxis2( dJointID j, dReal x, dReal y, dReal z )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT(joint->mode == dTransmissionIntersectingAxes,
+ "can't set individual axes in current mode" );
+
+ if (joint->node[1].body) {
+ dBodyVectorFromWorld(joint->node[1].body, x, y, z, joint->axes[1]);
+ dNormalize3(joint->axes[1]);
+ }
+
+ joint->update = 1;
+}
+
+void dJointSetTransmissionAnchor1( dJointID j, dReal x, dReal y, dReal z )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ if (joint->node[0].body) {
+ dBodyGetPosRelPoint(joint->node[0].body, x, y, z, joint->anchors[0]);
+ }
+
+ joint->update = 1;
+}
+
+void dJointSetTransmissionAnchor2( dJointID j, dReal x, dReal y, dReal z )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ if (joint->node[1].body) {
+ dBodyGetPosRelPoint(joint->node[1].body, x, y, z, joint->anchors[1]);
+ }
+
+ joint->update = 1;
+}
+
+void dJointGetTransmissionContactPoint1( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ dCopyVector3(result, joint->contacts[0]);
+}
+
+void dJointGetTransmissionContactPoint2( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ dCopyVector3(result, joint->contacts[1]);
+}
+
+void dJointGetTransmissionAxis( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+ dUASSERT(joint->mode == dTransmissionParallelAxes,
+ "axes must be queried individualy in current mode" );
+
+ if (joint->node[0].body) {
+ dBodyVectorToWorld(joint->node[0].body,
+ joint->axes[0][0],
+ joint->axes[0][1],
+ joint->axes[0][2],
+ result);
+ }
+}
+
+void dJointGetTransmissionAxis1( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ if (joint->node[0].body) {
+ dBodyVectorToWorld(joint->node[0].body,
+ joint->axes[0][0],
+ joint->axes[0][1],
+ joint->axes[0][2],
+ result);
+ }
+}
+
+void dJointGetTransmissionAxis2( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ if (joint->node[1].body) {
+ dBodyVectorToWorld(joint->node[1].body,
+ joint->axes[1][0],
+ joint->axes[1][1],
+ joint->axes[1][2],
+ result);
+ }
+}
+
+void dJointGetTransmissionAnchor1( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ if (joint->node[0].body) {
+ dBodyGetRelPointPos(joint->node[0].body,
+ joint->anchors[0][0],
+ joint->anchors[0][1],
+ joint->anchors[0][2],
+ result);
+ }
+}
+
+void dJointGetTransmissionAnchor2( dJointID j, dVector3 result )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( result, "bad result argument" );
+
+ if (joint->node[1].body) {
+ dBodyGetRelPointPos(joint->node[1].body,
+ joint->anchors[1][0],
+ joint->anchors[1][1],
+ joint->anchors[1][2],
+ result);
+ }
+}
+
+void dJointSetTransmissionParam( dJointID j, int parameter, dReal value )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ switch ( parameter ) {
+ case dParamCFM:
+ joint->cfm = value;
+ break;
+ case dParamERP:
+ joint->erp = value;
+ break;
+ }
+}
+
+
+dReal dJointGetTransmissionParam( dJointID j, int parameter )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ switch ( parameter ) {
+ case dParamCFM:
+ return joint->cfm;
+ case dParamERP:
+ return joint->erp;
+ default:
+ return 0;
+ }
+}
+
+void dJointSetTransmissionMode( dJointID j, int mode )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( mode == dTransmissionParallelAxes ||
+ mode == dTransmissionIntersectingAxes ||
+ mode == dTransmissionChainDrive, "invalid joint mode" );
+
+ joint->mode = mode;
+}
+
+
+int dJointGetTransmissionMode( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->mode;
+}
+
+void dJointSetTransmissionRatio( dJointID j, dReal ratio )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( joint->mode == dTransmissionParallelAxes,
+ "can't set ratio explicitly in current mode" );
+ dUASSERT( ratio > 0, "ratio must be positive" );
+
+ joint->ratio = ratio;
+}
+
+
+dReal dJointGetTransmissionRatio( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->ratio;
+}
+
+dReal dJointGetTransmissionAngle1( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->phase[0];
+}
+
+dReal dJointGetTransmissionAngle2( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->phase[1];
+}
+
+dReal dJointGetTransmissionRadius1( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->radii[0];
+}
+
+dReal dJointGetTransmissionRadius2( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->radii[1];
+}
+
+void dJointSetTransmissionRadius1( dJointID j, dReal radius )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( joint->mode == dTransmissionChainDrive,
+ "can't set wheel radius explicitly in current mode" );
+
+ joint->radii[0] = radius;
+}
+
+void dJointSetTransmissionRadius2( dJointID j, dReal radius )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+ dUASSERT( joint->mode == dTransmissionChainDrive,
+ "can't set wheel radius explicitly in current mode" );
+
+ joint->radii[1] = radius;
+}
+
+dReal dJointGetTransmissionBacklash( dJointID j )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ return joint->backlash;
+}
+
+void dJointSetTransmissionBacklash( dJointID j, dReal backlash )
+{
+ dxJointTransmission* joint = static_cast<dxJointTransmission*>(j);
+ dUASSERT( joint, "bad joint argument" );
+
+ joint->backlash = backlash;
+}
+
+dJointType
+dxJointTransmission::type() const
+{
+ return dJointTypeTransmission;
+}
+
+sizeint
+dxJointTransmission::size() const
+{
+ return sizeof( *this );
+}