com.bulletphysics.dynamics.constraintsolver.Generic6DofConstraint Maven / Gradle / Ivy
/*
* Java port of Bullet (c) 2008 Martin Dvorak
*
* Bullet Continuous Collision Detection and Physics Library
* Copyright (c) 2003-2008 Erwin Coumans http://www.bulletphysics.com/
*
* This software is provided 'as-is', without any express or implied warranty.
* In no event will the authors be held liable for any damages arising from
* the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
/*
2007-09-09
btGeneric6DofConstraint Refactored by Francisco Le�n
email: [email protected]
http://gimpact.sf.net
*/
package com.bulletphysics.dynamics.constraintsolver;
import com.bulletphysics.BulletGlobals;
import com.bulletphysics.dynamics.RigidBody;
import com.bulletphysics.linearmath.MatrixUtil;
import com.bulletphysics.linearmath.Transform;
///
import com.bulletphysics.linearmath.VectorUtil;
import cz.advel.stack.Stack;
import javax.vecmath.Matrix3f;
import javax.vecmath.Vector3f;
/*!
*/
/**
* Generic6DofConstraint between two rigidbodies each with a pivot point that descibes
* the axis location in local space.
*
* Generic6DofConstraint can leave any of the 6 degree of freedom "free" or "locked".
* Currently this limit supports rotational motors.
*
*
* - For linear limits, use {@link #setLinearUpperLimit}, {@link #setLinearLowerLimit}.
* You can set the parameters with the {@link TranslationalLimitMotor} structure accsesible
* through the {@link #getTranslationalLimitMotor} method.
* At this moment translational motors are not supported. May be in the future.
*
* - For angular limits, use the {@link RotationalLimitMotor} structure for configuring
* the limit. This is accessible through {@link #getRotationalLimitMotor} method,
* this brings support for limit parameters and motors.
*
* - Angulars limits have these possible ranges:
*
*
* AXIS
* MIN ANGLE
* MAX ANGLE
*
* X
* -PI
* PI
*
* Y
* -PI/2
* PI/2
*
* Z
* -PI/2
* PI/2
*
*
*
*
*
* @author jezek2
*/
public class Generic6DofConstraint extends TypedConstraint {
protected final Transform frameInA = new Transform(); //!< the constraint space w.r.t body A
protected final Transform frameInB = new Transform(); //!< the constraint space w.r.t body B
protected final JacobianEntry[] jacLinear/*[3]*/ = new JacobianEntry[] { new JacobianEntry(), new JacobianEntry(), new JacobianEntry() }; //!< 3 orthogonal linear constraints
protected final JacobianEntry[] jacAng/*[3]*/ = new JacobianEntry[] { new JacobianEntry(), new JacobianEntry(), new JacobianEntry() }; //!< 3 orthogonal angular constraints
protected final TranslationalLimitMotor linearLimits = new TranslationalLimitMotor();
protected final RotationalLimitMotor[] angularLimits/*[3]*/ = new RotationalLimitMotor[] { new RotationalLimitMotor(), new RotationalLimitMotor(), new RotationalLimitMotor() };
protected float timeStep;
protected final Transform calculatedTransformA = new Transform();
protected final Transform calculatedTransformB = new Transform();
protected final Vector3f calculatedAxisAngleDiff = new Vector3f();
protected final Vector3f[] calculatedAxis/*[3]*/ = new Vector3f[] { new Vector3f(), new Vector3f(), new Vector3f() };
protected final Vector3f anchorPos = new Vector3f(); // point betwen pivots of bodies A and B to solve linear axes
protected boolean useLinearReferenceFrameA;
public Generic6DofConstraint() {
super(TypedConstraintType.D6_CONSTRAINT_TYPE);
useLinearReferenceFrameA = true;
}
public Generic6DofConstraint(RigidBody rbA, RigidBody rbB, Transform frameInA, Transform frameInB, boolean useLinearReferenceFrameA) {
super(TypedConstraintType.D6_CONSTRAINT_TYPE, rbA, rbB);
this.frameInA.set(frameInA);
this.frameInB.set(frameInB);
this.useLinearReferenceFrameA = useLinearReferenceFrameA;
}
private static float getMatrixElem(Matrix3f mat, int index) {
int i = index % 3;
int j = index / 3;
return mat.getElement(i, j);
}
/**
* MatrixToEulerXYZ from http://www.geometrictools.com/LibFoundation/Mathematics/Wm4Matrix3.inl.html
*/
private static boolean matrixToEulerXYZ(Matrix3f mat, Vector3f xyz) {
// // rot = cy*cz -cy*sz sy
// // cz*sx*sy+cx*sz cx*cz-sx*sy*sz -cy*sx
// // -cx*cz*sy+sx*sz cz*sx+cx*sy*sz cx*cy
//
if (getMatrixElem(mat, 2) < 1.0f) {
if (getMatrixElem(mat, 2) > -1.0f) {
xyz.x = (float) Math.atan2(-getMatrixElem(mat, 5), getMatrixElem(mat, 8));
xyz.y = (float) Math.asin(getMatrixElem(mat, 2));
xyz.z = (float) Math.atan2(-getMatrixElem(mat, 1), getMatrixElem(mat, 0));
return true;
}
else {
// WARNING. Not unique. XA - ZA = -atan2(r10,r11)
xyz.x = -(float) Math.atan2(getMatrixElem(mat, 3), getMatrixElem(mat, 4));
xyz.y = -BulletGlobals.SIMD_HALF_PI;
xyz.z = 0.0f;
return false;
}
}
else {
// WARNING. Not unique. XAngle + ZAngle = atan2(r10,r11)
xyz.x = (float) Math.atan2(getMatrixElem(mat, 3), getMatrixElem(mat, 4));
xyz.y = BulletGlobals.SIMD_HALF_PI;
xyz.z = 0.0f;
}
return false;
}
/**
* Calcs the euler angles between the two bodies.
*/
protected void calculateAngleInfo() {
Matrix3f mat = Stack.alloc(Matrix3f.class);
Matrix3f relative_frame = Stack.alloc(Matrix3f.class);
mat.set(calculatedTransformA.basis);
MatrixUtil.invert(mat);
relative_frame.mul(mat, calculatedTransformB.basis);
matrixToEulerXYZ(relative_frame, calculatedAxisAngleDiff);
// in euler angle mode we do not actually constrain the angular velocity
// along the axes axis[0] and axis[2] (although we do use axis[1]) :
//
// to get constrain w2-w1 along ...not
// ------ --------------------- ------
// d(angle[0])/dt = 0 ax[1] x ax[2] ax[0]
// d(angle[1])/dt = 0 ax[1]
// d(angle[2])/dt = 0 ax[0] x ax[1] ax[2]
//
// constraining w2-w1 along an axis 'a' means that a'*(w2-w1)=0.
// to prove the result for angle[0], write the expression for angle[0] from
// GetInfo1 then take the derivative. to prove this for angle[2] it is
// easier to take the euler rate expression for d(angle[2])/dt with respect
// to the components of w and set that to 0.
Vector3f axis0 = Stack.alloc(Vector3f.class);
calculatedTransformB.basis.getColumn(0, axis0);
Vector3f axis2 = Stack.alloc(Vector3f.class);
calculatedTransformA.basis.getColumn(2, axis2);
calculatedAxis[1].cross(axis2, axis0);
calculatedAxis[0].cross(calculatedAxis[1], axis2);
calculatedAxis[2].cross(axis0, calculatedAxis[1]);
// if(m_debugDrawer)
// {
//
// char buff[300];
// sprintf(buff,"\n X: %.2f ; Y: %.2f ; Z: %.2f ",
// m_calculatedAxisAngleDiff[0],
// m_calculatedAxisAngleDiff[1],
// m_calculatedAxisAngleDiff[2]);
// m_debugDrawer->reportErrorWarning(buff);
// }
}
/**
* Calcs global transform of the offsets.
* Calcs the global transform for the joint offset for body A an B, and also calcs the agle differences between the bodies.
*
* See also: Generic6DofConstraint.getCalculatedTransformA, Generic6DofConstraint.getCalculatedTransformB, Generic6DofConstraint.calculateAngleInfo
*/
public void calculateTransforms() {
rbA.getCenterOfMassTransform(calculatedTransformA);
calculatedTransformA.mul(frameInA);
rbB.getCenterOfMassTransform(calculatedTransformB);
calculatedTransformB.mul(frameInB);
calculateAngleInfo();
}
protected void buildLinearJacobian(/*JacobianEntry jacLinear*/int jacLinear_index, Vector3f normalWorld, Vector3f pivotAInW, Vector3f pivotBInW) {
Matrix3f mat1 = rbA.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat1.transpose();
Matrix3f mat2 = rbB.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat2.transpose();
Vector3f tmpVec = Stack.alloc(Vector3f.class);
Vector3f tmp1 = Stack.alloc(Vector3f.class);
tmp1.sub(pivotAInW, rbA.getCenterOfMassPosition(tmpVec));
Vector3f tmp2 = Stack.alloc(Vector3f.class);
tmp2.sub(pivotBInW, rbB.getCenterOfMassPosition(tmpVec));
jacLinear[jacLinear_index].init(
mat1,
mat2,
tmp1,
tmp2,
normalWorld,
rbA.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)),
rbA.getInvMass(),
rbB.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)),
rbB.getInvMass());
}
protected void buildAngularJacobian(/*JacobianEntry jacAngular*/int jacAngular_index, Vector3f jointAxisW) {
Matrix3f mat1 = rbA.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat1.transpose();
Matrix3f mat2 = rbB.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat2.transpose();
jacAng[jacAngular_index].init(jointAxisW,
mat1,
mat2,
rbA.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)),
rbB.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)));
}
/**
* Test angular limit.
* Calculates angular correction and returns true if limit needs to be corrected.
* Generic6DofConstraint.buildJacobian must be called previously.
*/
public boolean testAngularLimitMotor(int axis_index) {
float angle = VectorUtil.getCoord(calculatedAxisAngleDiff, axis_index);
// test limits
angularLimits[axis_index].testLimitValue(angle);
return angularLimits[axis_index].needApplyTorques();
}
@Override
public void buildJacobian() {
// Clear accumulated impulses for the next simulation step
linearLimits.accumulatedImpulse.set(0f, 0f, 0f);
for (int i=0; i<3; i++) {
angularLimits[i].accumulatedImpulse = 0f;
}
// calculates transform
calculateTransforms();
Vector3f tmpVec = Stack.alloc(Vector3f.class);
// const btVector3& pivotAInW = m_calculatedTransformA.getOrigin();
// const btVector3& pivotBInW = m_calculatedTransformB.getOrigin();
calcAnchorPos();
Vector3f pivotAInW = Stack.alloc(anchorPos);
Vector3f pivotBInW = Stack.alloc(anchorPos);
// not used here
// btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition();
// btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition();
Vector3f normalWorld = Stack.alloc(Vector3f.class);
// linear part
for (int i=0; i<3; i++) {
if (linearLimits.isLimited(i)) {
if (useLinearReferenceFrameA) {
calculatedTransformA.basis.getColumn(i, normalWorld);
}
else {
calculatedTransformB.basis.getColumn(i, normalWorld);
}
buildLinearJacobian(
/*jacLinear[i]*/i, normalWorld,
pivotAInW, pivotBInW);
}
}
// angular part
for (int i=0; i<3; i++) {
// calculates error angle
if (testAngularLimitMotor(i)) {
this.getAxis(i, normalWorld);
// Create angular atom
buildAngularJacobian(/*jacAng[i]*/i, normalWorld);
}
}
}
@Override
public void solveConstraint(float timeStep) {
this.timeStep = timeStep;
//calculateTransforms();
int i;
// linear
Vector3f pointInA = Stack.alloc(calculatedTransformA.origin);
Vector3f pointInB = Stack.alloc(calculatedTransformB.origin);
float jacDiagABInv;
Vector3f linear_axis = Stack.alloc(Vector3f.class);
for (i = 0; i < 3; i++) {
if (linearLimits.isLimited(i)) {
jacDiagABInv = 1f / jacLinear[i].getDiagonal();
if (useLinearReferenceFrameA) {
calculatedTransformA.basis.getColumn(i, linear_axis);
}
else {
calculatedTransformB.basis.getColumn(i, linear_axis);
}
linearLimits.solveLinearAxis(
this.timeStep,
jacDiagABInv,
rbA, pointInA,
rbB, pointInB,
i, linear_axis, anchorPos);
}
}
// angular
Vector3f angular_axis = Stack.alloc(Vector3f.class);
float angularJacDiagABInv;
for (i = 0; i < 3; i++) {
if (angularLimits[i].needApplyTorques()) {
// get axis
getAxis(i, angular_axis);
angularJacDiagABInv = 1f / jacAng[i].getDiagonal();
angularLimits[i].solveAngularLimits(this.timeStep, angular_axis, angularJacDiagABInv, rbA, rbB);
}
}
}
public void updateRHS(float timeStep) {
}
/**
* Get the rotation axis in global coordinates.
* Generic6DofConstraint.buildJacobian must be called previously.
*/
public Vector3f getAxis(int axis_index, Vector3f out) {
out.set(calculatedAxis[axis_index]);
return out;
}
/**
* Get the relative Euler angle.
* Generic6DofConstraint.buildJacobian must be called previously.
*/
public float getAngle(int axis_index) {
return VectorUtil.getCoord(calculatedAxisAngleDiff, axis_index);
}
/**
* Gets the global transform of the offset for body A.
* See also: Generic6DofConstraint.getFrameOffsetA, Generic6DofConstraint.getFrameOffsetB, Generic6DofConstraint.calculateAngleInfo.
*/
public Transform getCalculatedTransformA(Transform out) {
out.set(calculatedTransformA);
return out;
}
/**
* Gets the global transform of the offset for body B.
* See also: Generic6DofConstraint.getFrameOffsetA, Generic6DofConstraint.getFrameOffsetB, Generic6DofConstraint.calculateAngleInfo.
*/
public Transform getCalculatedTransformB(Transform out) {
out.set(calculatedTransformB);
return out;
}
public Transform getFrameOffsetA(Transform out) {
out.set(frameInA);
return out;
}
public Transform getFrameOffsetB(Transform out) {
out.set(frameInB);
return out;
}
public void setLinearLowerLimit(Vector3f linearLower) {
linearLimits.lowerLimit.set(linearLower);
}
public void setLinearUpperLimit(Vector3f linearUpper) {
linearLimits.upperLimit.set(linearUpper);
}
public void setAngularLowerLimit(Vector3f angularLower) {
angularLimits[0].loLimit = angularLower.x;
angularLimits[1].loLimit = angularLower.y;
angularLimits[2].loLimit = angularLower.z;
}
public void setAngularUpperLimit(Vector3f angularUpper) {
angularLimits[0].hiLimit = angularUpper.x;
angularLimits[1].hiLimit = angularUpper.y;
angularLimits[2].hiLimit = angularUpper.z;
}
/**
* Retrieves the angular limit informacion.
*/
public RotationalLimitMotor getRotationalLimitMotor(int index) {
return angularLimits[index];
}
/**
* Retrieves the limit informacion.
*/
public TranslationalLimitMotor getTranslationalLimitMotor() {
return linearLimits;
}
/**
* first 3 are linear, next 3 are angular
*/
public void setLimit(int axis, float lo, float hi) {
if (axis < 3) {
VectorUtil.setCoord(linearLimits.lowerLimit, axis, lo);
VectorUtil.setCoord(linearLimits.upperLimit, axis, hi);
}
else {
angularLimits[axis - 3].loLimit = lo;
angularLimits[axis - 3].hiLimit = hi;
}
}
/**
* Test limit.
* - free means upper < lower,
* - locked means upper == lower
* - limited means upper > lower
* - limitIndex: first 3 are linear, next 3 are angular
*/
public boolean isLimited(int limitIndex) {
if (limitIndex < 3) {
return linearLimits.isLimited(limitIndex);
}
return angularLimits[limitIndex - 3].isLimited();
}
// overridable
public void calcAnchorPos() {
float imA = rbA.getInvMass();
float imB = rbB.getInvMass();
float weight;
if (imB == 0f) {
weight = 1f;
}
else {
weight = imA / (imA + imB);
}
Vector3f pA = calculatedTransformA.origin;
Vector3f pB = calculatedTransformB.origin;
Vector3f tmp1 = Stack.alloc(Vector3f.class);
Vector3f tmp2 = Stack.alloc(Vector3f.class);
tmp1.scale(weight, pA);
tmp2.scale(1f - weight, pB);
anchorPos.add(tmp1, tmp2);
}
}