Plane::Plane( const cc::Vec3f& a, const cc::Vec3f& b, const cc::Vec3f& c ) {
const cc::Vec3f ab = b - a;
const cc::Vec3f ac = c - a;
const cc::Vec3f cross = ab.cross(ac);
_normal = cross.normalized();
_d = -_normal.dot(a);
}
static Plane constructFromPointNormal( const cc::Vec3f& point, const cc::Vec3f& normal ) {
Plane result;
const cc::Vec3f normalizedNormal = normal.normalized();
result.normal = normalizedNormal;
result.constant = -point.dot(normalizedNormal);
return result;
}
void OpenCloth::computeForces( float deltaTime ) {
for( int i = 0; i < _totalPoints; ++i ) {
_forces[i].x = _forces[i].y = _forces[i].z = 0.0f;
const cc::Vec3f velocity = getVerletVelocity(_positions[i], _lastPositions[i], deltaTime);
if( (i != 0) && (i != _divsX) ) {
_forces[i] += _gravity * _mass;
}
_forces[i] += _damping * velocity;
}
for( int i = 0; i < _springCount; ++i ) {
const cc::Vec3f& p1 = _positions[_springs[i].p1];
const cc::Vec3f& p1Last = _lastPositions[_springs[i].p1];
const cc::Vec3f& p2 = _positions[_springs[i].p2];
const cc::Vec3f& p2Last = _lastPositions[_springs[i].p2];
const cc::Vec3f v1 = getVerletVelocity(p1, p1Last, deltaTime);
const cc::Vec3f v2 = getVerletVelocity(p2, p2Last, deltaTime);
const cc::Vec3f deltaP = p1 - p2;
const cc::Vec3f deltaV = v1 - v2;
const float dist = deltaP.magnitude();
const float leftTerm = -_springs[i].ks * (dist - _springs[i].restLength);
const float rightTerm = _springs[i].kd * (deltaV.dot(deltaP) / dist);
const cc::Vec3f springForce = (leftTerm + rightTerm) * deltaP.normalized();
if( _springs[i].p1 != 0 && _springs[i].p1 != _divsX ) {
_forces[_springs[i].p1] += springForce;
}
if( _springs[i].p2 != 0 && _springs[i].p2 != _divsX ) {
_forces[_springs[i].p2] -= springForce;
}
}
}
cc::Vec3f GeometricPlane::getNormal() {
const cc::Vec3f p0 = (_xform.getWorld() * cc::Vec4f(_verts[0].position, 1.0f)).truncated();
const cc::Vec3f p1 = (_xform.getWorld() * cc::Vec4f(_verts[1].position, 1.0f)).truncated();
const cc::Vec3f p2 = (_xform.getWorld() * cc::Vec4f(_verts[2].position, 1.0f)).truncated();
const cc::Vec3f p3 = (_xform.getWorld() * cc::Vec4f(_verts[3].position, 1.0f)).truncated();
const cc::Vec3f a = p1 - p0;
const cc::Vec3f b = p3 - p0;
return a.cross(b).normalized();
}
void OpenCloth::addSpring( int* idx, int a, int b, float ks, float kd ) {
_springs[*idx].p1 = a;
_springs[*idx].p2 = b;
_springs[*idx].ks = ks;
_springs[*idx].kd = kd;
const cc::Vec3f deltaP = _positions[a] - _positions[b];
_springs[*idx].restLength = sqrtf(deltaP.dot(deltaP));
*idx += 1;
}
static void setVec3Length( cc::Vec3f& vec, float newLength ) {
const float length = vec.magnitude();
if( length != 0.0f ) {
const float factor = newLength / length;
vec.x *= factor;
vec.y *= factor;
vec.z *= factor;
}
}
bool ClipMesh::getTriangles( std::vector<int>& indices ) {
const size_t numFaces = _faces.size();
for( size_t currFace = 0; currFace < numFaces; ++currFace ) {
CFace& face = _faces[currFace];
if( !face.visible ) {
continue;
}
const size_t numEdges = face.edges.size();
//assert(numEdges >= 3); // unexpected condition
if( numEdges < 3 ) {
return false;
}
std::vector<int> vOrdered(numEdges+1);
if( !orderVertices(face, vOrdered) ) {
return false;
}
const int v0 = vOrdered[0];
const int v2 = vOrdered[numEdges - 1];
const int v1 = vOrdered[(numEdges - 1) >> 1];
const cc::Vec3f diff1 = _vertices[v1].point - _vertices[v0].point;
const cc::Vec3f diff2 = _vertices[v2].point - _vertices[v0].point;
const float sgnVolume = face.normal.dot(diff1.cross(diff2));
if( sgnVolume < 0.0f ) { // feel free to invert this test
// clockwise, need to swap
for( unsigned int i = 1; i + 1 < numEdges; ++i ) {
indices.push_back(v0);
indices.push_back(vOrdered[i + 1]);
indices.push_back(vOrdered[i]);
}
} else {
// counterclockwise
for( unsigned int i = 1; i + 1 < numEdges; ++i ) {
indices.push_back(v0);
indices.push_back(vOrdered[i]);
indices.push_back(vOrdered[i + 1]);
}
}
}
return true;
}
