// ------------------------------------------------------------------------------------------------
// Compute the normal of the last polygon in the given mesh
IfcVector3 TempMesh::ComputeLastPolygonNormal(bool normalize) const
{
size_t total = vertcnt.back(), vidx = verts.size() - total;
std::vector<IfcFloat> temp((total+2)*3);
for(size_t vofs = 0, cnt = 0; vofs < total; ++vofs) {
const IfcVector3& v = verts[vidx+vofs];
temp[cnt++] = v.x;
temp[cnt++] = v.y;
temp[cnt++] = v.z;
}
IfcVector3 nor;
NewellNormal<3,3,3>(nor,total,&temp[0],&temp[1],&temp[2]);
return normalize ? nor.Normalize() : nor;
}
// ------------------------------------------------------------------------------------------------
IfcVector3 TempMesh::ComputePolygonNormal(const IfcVector3* vtcs, size_t cnt, bool normalize)
{
std::vector<IfcFloat> temp((cnt+2)*3);
for( size_t vofs = 0, i = 0; vofs < cnt; ++vofs )
{
const IfcVector3& v = vtcs[vofs];
temp[i++] = v.x;
temp[i++] = v.y;
temp[i++] = v.z;
}
IfcVector3 nor;
NewellNormal<3, 3, 3>(nor, cnt, &temp[0], &temp[1], &temp[2]);
return normalize ? nor.Normalize() : nor;
}
// ------------------------------------------------------------------------------------------------
void ConvertDirection(IfcVector3& out, const IfcDirection& in)
{
out = IfcVector3();
for(size_t i = 0; i < in.DirectionRatios.size(); ++i) {
out[i] = in.DirectionRatios[i];
}
const IfcFloat len = out.Length();
if (len<1e-6) {
IFCImporter::LogWarn("direction vector magnitude too small, normalization would result in a division by zero");
return;
}
out /= len;
}
// ------------------------------------------------------------------------------------------------
IfcMatrix3 DerivePlaneCoordinateSpace(const TempMesh& curmesh, bool& ok, IfcVector3& norOut)
{
const std::vector<IfcVector3>& out = curmesh.verts;
IfcMatrix3 m;
ok = true;
// The input "mesh" must be a single polygon
const size_t s = out.size();
assert(curmesh.vertcnt.size() == 1 && curmesh.vertcnt.back() == s);
const IfcVector3 any_point = out[s-1];
IfcVector3 nor;
// The input polygon is arbitrarily shaped, therefore we might need some tries
// until we find a suitable normal. Note that Newell's algorithm would give
// a more robust result, but this variant also gives us a suitable first
// axis for the 2D coordinate space on the polygon plane, exploiting the
// fact that the input polygon is nearly always a quad.
bool done = false;
size_t i, j;
for (i = 0; !done && i < s-2; done || ++i) {
for (j = i+1; j < s-1; ++j) {
nor = -((out[i]-any_point)^(out[j]-any_point));
if(std::fabs(nor.Length()) > 1e-8f) {
done = true;
break;
}
}
}
if(!done) {
ok = false;
return m;
}
nor.Normalize();
norOut = nor;
IfcVector3 r = (out[i]-any_point);
r.Normalize();
//if(d) {
// *d = -any_point * nor;
//}
// Reconstruct orthonormal basis
// XXX use Gram Schmidt for increased robustness
IfcVector3 u = r ^ nor;
u.Normalize();
m.a1 = r.x;
m.a2 = r.y;
m.a3 = r.z;
m.b1 = u.x;
m.b2 = u.y;
m.b3 = u.z;
m.c1 = -nor.x;
m.c2 = -nor.y;
m.c3 = -nor.z;
return m;
}
// ------------------------------------------------------------------------------------------------
void ProcessSweptDiskSolid(const IfcSweptDiskSolid solid, TempMesh& result, ConversionData& conv)
{
const Curve* const curve = Curve::Convert(*solid.Directrix, conv);
if(!curve) {
IFCImporter::LogError("failed to convert Directrix curve (IfcSweptDiskSolid)");
return;
}
const unsigned int cnt_segments = 16;
const IfcFloat deltaAngle = AI_MATH_TWO_PI/cnt_segments;
const size_t samples = curve->EstimateSampleCount(solid.StartParam,solid.EndParam);
result.verts.reserve(cnt_segments * samples * 4);
result.vertcnt.reserve((cnt_segments - 1) * samples);
std::vector<IfcVector3> points;
points.reserve(cnt_segments * samples);
TempMesh temp;
curve->SampleDiscrete(temp,solid.StartParam,solid.EndParam);
const std::vector<IfcVector3>& curve_points = temp.verts;
if(curve_points.empty()) {
IFCImporter::LogWarn("curve evaluation yielded no points (IfcSweptDiskSolid)");
return;
}
IfcVector3 current = curve_points[0];
IfcVector3 previous = current;
IfcVector3 next;
IfcVector3 startvec;
startvec.x = 1.0f;
startvec.y = 1.0f;
startvec.z = 1.0f;
unsigned int last_dir = 0;
// generate circles at the sweep positions
for(size_t i = 0; i < samples; ++i) {
if(i != samples - 1) {
next = curve_points[i + 1];
}
// get a direction vector reflecting the approximate curvature (i.e. tangent)
IfcVector3 d = (current-previous) + (next-previous);
d.Normalize();
// figure out an arbitrary point q so that (p-q) * d = 0,
// try to maximize ||(p-q)|| * ||(p_last-q_last)||
IfcVector3 q;
bool take_any = false;
for (unsigned int i = 0; i < 2; ++i, take_any = true) {
if ((last_dir == 0 || take_any) && std::abs(d.x) > 1e-6) {
q.y = startvec.y;
q.z = startvec.z;
q.x = -(d.y * q.y + d.z * q.z) / d.x;
last_dir = 0;
break;
}
else if ((last_dir == 1 || take_any) && std::abs(d.y) > 1e-6) {
q.x = startvec.x;
q.z = startvec.z;
q.y = -(d.x * q.x + d.z * q.z) / d.y;
last_dir = 1;
break;
}
else if ((last_dir == 2 && std::abs(d.z) > 1e-6) || take_any) {
q.y = startvec.y;
q.x = startvec.x;
q.z = -(d.y * q.y + d.x * q.x) / d.z;
last_dir = 2;
break;
}
}
q *= solid.Radius / q.Length();
startvec = q;
// generate a rotation matrix to rotate q around d
IfcMatrix4 rot;
IfcMatrix4::Rotation(deltaAngle,d,rot);
for (unsigned int seg = 0; seg < cnt_segments; ++seg, q *= rot ) {
points.push_back(q + current);
}
previous = current;
current = next;
}
// make quads
for(size_t i = 0; i < samples - 1; ++i) {
const aiVector3D& this_start = points[ i * cnt_segments ];
// locate corresponding point on next sample ring
unsigned int best_pair_offset = 0;
float best_distance_squared = 1e10f;
for (unsigned int seg = 0; seg < cnt_segments; ++seg) {
const aiVector3D& p = points[ (i+1) * cnt_segments + seg];
const float l = (p-this_start).SquareLength();
if(l < best_distance_squared) {
best_pair_offset = seg;
best_distance_squared = l;
}
}
for (unsigned int seg = 0; seg < cnt_segments; ++seg) {
result.verts.push_back(points[ i * cnt_segments + (seg % cnt_segments)]);
result.verts.push_back(points[ i * cnt_segments + (seg + 1) % cnt_segments]);
result.verts.push_back(points[ (i+1) * cnt_segments + ((seg + 1 + best_pair_offset) % cnt_segments)]);
result.verts.push_back(points[ (i+1) * cnt_segments + ((seg + best_pair_offset) % cnt_segments)]);
IfcVector3& v1 = *(result.verts.end()-1);
IfcVector3& v2 = *(result.verts.end()-2);
IfcVector3& v3 = *(result.verts.end()-3);
IfcVector3& v4 = *(result.verts.end()-4);
if (((v4-v3) ^ (v4-v1)) * (v4 - curve_points[i]) < 0.0f) {
std::swap(v4, v1);
std::swap(v3, v2);
}
result.vertcnt.push_back(4);
}
}
IFCImporter::LogDebug("generate mesh procedurally by sweeping a disk along a curve (IfcSweptDiskSolid)");
}
