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use relative mass when enforcing ContactPoint

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This commit is contained in:
Andrew Meadows 2014-08-18 12:49:47 -07:00
parent 54851c5ced
commit fe5f9f8fe5
1 changed files with 27 additions and 4 deletions
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31
libraries/shared/src/ContactPoint.cpp
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@ -96,10 +96,10 @@ float ContactPoint::enforce() {
bool constraintViolation = (pDotN > CONTACT_PENETRATION_ALLOWANCE);
// the contact point will be the average of the two points on the shapes
_contactPoint = 0.5f * (pointA + pointB);
_contactPoint = _relativeMassA * pointA + _relativeMassB * pointB;
if (constraintViolation) {
for (int i = 0; i < _numPoints; ++i) {
for (int i = 0; i < _numPointsA; ++i) {
VerletPoint* point = _points[i];
glm::vec3 offset = _offsets[i];
@ -111,8 +111,31 @@ float ContactPoint::enforce() {
// use the relative sizes of the components to decide how much perpenducular delta to use
// perpendicular < parallel ==> static friction ==> perpFactor = 1.0
// perpendicular > parallel ==> dynamic friction ==> cap to length of paraDelta ==> perpFactor < 1.0
float paraLength = glm::length(paraDelta);
float perpLength = glm::length(perpDelta);
float paraLength = _relativeMassB * glm::length(paraDelta);
float perpLength = _relativeMassA * glm::length(perpDelta);
float perpFactor = (perpLength > paraLength && perpLength > EPSILON) ? (paraLength / perpLength) : 1.0f;
// recombine the two components to get the final delta
delta = paraDelta + perpFactor * perpDelta;
glm::vec3 targetPosition = point->_position + delta;
_distances[i] = glm::distance(_contactPoint, targetPosition);
point->_position += delta;
}
for (int i = _numPointsA; i < _numPoints; ++i) {
VerletPoint* point = _points[i];
glm::vec3 offset = _offsets[i];
// split delta into parallel and perpendicular components
glm::vec3 delta = _contactPoint + offset - point->_position;
glm::vec3 paraDelta = glm::dot(delta, _normal) * _normal;
glm::vec3 perpDelta = delta - paraDelta;
// use the relative sizes of the components to decide how much perpenducular delta to use
// perpendicular < parallel ==> static friction ==> perpFactor = 1.0
// perpendicular > parallel ==> dynamic friction ==> cap to length of paraDelta ==> perpFactor < 1.0
float paraLength = _relativeMassA * glm::length(paraDelta);
float perpLength = _relativeMassB * glm::length(perpDelta);
float perpFactor = (perpLength > paraLength && perpLength > EPSILON) ? (paraLength / perpLength) : 1.0f;
// recombine the two components to get the final delta