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Fixes curve segment placement issues
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@RickBrice
RickBrice committed Apr 10, 2024
1 parent a34da81 commit 4807e5b
Showing 1 changed file with 36 additions and 37 deletions.
73 changes: 36 additions & 37 deletions src/ifcgeom/mapping/IfcCurveSegment.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ class segment_geometry_adjuster {
// To determine the geometry adjustments the curve segment needs to be evaluated
// without adjustments. This function toggles the application of geometry adjustments
void enable_adjustments(bool adjustments) { adjustments_ = adjustments; }
bool enable_adjustments() const { return adjustments_; }

// This object doesn't have access to the eval_ property of the curve_segment_evaluator.
// The end point of the segment being adjusted, without adjustments, is computed externally
Expand Down Expand Up @@ -765,7 +766,7 @@ class curve_segment_evaluator {

void operator()(const IfcSchema::IfcCircle* c)
{
if (segment_type_ == ST_HORIZONTAL) {
if (segment_type_ == ST_HORIZONTAL || segment_type_ == ST_VERTICAL) {
auto R = c->Radius() * length_unit_;
auto position = c->Position()->as<IfcSchema::IfcAxis2Placement2D>();
auto location = position->Location()->as<IfcSchema::IfcCartesianPoint>();
Expand All @@ -787,8 +788,12 @@ class curve_segment_evaluator {
pcDy = dr[1];
}

// angle from X = 0 to the parent curve X-axis
auto pc_axis_angle = atan2(pcDy, pcDx);
// sweep angle from the parent curve X-axis to the first point on the trimmed curve
auto sweep_start_angle = start_ / R;
// angle from X = 0 to the first point on the trimmed curve
auto start_angle = atan2(pcDy, pcDx);
auto start_angle = pc_axis_angle + sweep_start_angle;

// first point on the trimmed curve
auto pcStartX = pcCenterX + R * cos(start_angle);
Expand All @@ -799,11 +804,30 @@ class curve_segment_evaluator {
geometry_adjuster_ = std::make_shared<GEOMETRY_ADJUSTER>(mapping_, inst_, next_inst_);

projected_length_ = length_;
eval_ = [R, pcCenterX, pcCenterY, pcStartX, pcStartY, start_angle, sign_l, geometry_adjuster = geometry_adjuster_](double u)
eval_ = [R, pcCenterX, pcCenterY, pcStartX, pcStartY, pc_axis_angle, start_angle, sign_l, segment_type=segment_type_, geometry_adjuster = geometry_adjuster_](double u)
{
// If segment_type == ST_VERTICAL and adjustments are enabled the input u is measured along the horizontal.
// u needs to be the arc length along the circle. If adjustments are disabled u is one of the end points so its arc length
if (segment_type == ST_VERTICAL && geometry_adjuster->enable_adjustments()) {
// x and y are distance from center of circle as if circle was centered at (0,0)
auto x = pcStartX + u - pcCenterX;
auto y = -sign_l*sqrt(R * R - x * x);
// move x and y so they are relative to the center of the circle
x += pcCenterX;
y += pcCenterY;
// compute the distance between the start point and (x,y)
auto c = sqrt(pow(x - pcStartX,2.0) + pow(y - pcStartY,2.0));
// compute the subtended angle
// c = 2R*sin(delta/2)
auto delta = 2 * asin(c / (2 * R));
// compute the arc length (this will always be a positive value)
u = R * fabs(delta);
}

// u is measured along the circle
// angle from the parent curve X-axis to the current point
auto angle = start_angle + sign_l * u / R;
// angle from the X=0 axis to the current point
auto delta = sign_l * u / R;
auto angle = start_angle + delta;

// point on the parent curve
auto pcX = R * cos(angle) + pcCenterX;
Expand All @@ -819,9 +843,12 @@ class curve_segment_evaluator {
auto csX = pcX * cos(rotate) - pcY * sin(rotate);
auto csY = pcX * sin(rotate) + pcY * cos(rotate);

// slope of the parent curve
auto dx = -sin(angle + rotate);
auto dy = cos(angle + rotate);
// direction of vector tangent to the curve segment
// at this point the curve has been rotated so the start is
// tangent to [1,0] so dx, dy in that coordinate system
// is dependent only on delta
auto dx = cos(delta);
auto dy = sin(delta);

// transform the point into the curve segment coordinate system
Eigen::Matrix4d m = Eigen::Matrix4d::Identity();
Expand All @@ -831,35 +858,7 @@ class curve_segment_evaluator {
return geometry_adjuster->transform_and_adjust(u, m);
};
}
else if (segment_type_ == ST_VERTICAL) {
auto R = c->Radius() * length_unit_;
auto start_angle = start_/R;
auto end_angle = start_angle + length_ / R;
auto u_end = R * (cos(end_angle)-cos(start_angle));
auto sign_l = sign(length_);

const auto& p = taxonomy::cast<taxonomy::matrix4>(mapping_->map(inst_->Placement()))->ccomponents();
auto ys = p.col(3)(1) * length_unit_;

projected_length_ = u_end;

eval_ = [ys,R,u_end,start_angle,end_angle,sign_l](double u) -> Eigen::Matrix4d {
// u is measured along the x-axis, not along the circle
auto theta = start_angle + u * (end_angle - start_angle) / u_end;
//auto y = ys + R * (sin(theta) - sin(start_angle));
auto y = ys - sign_l*(sqrt(R * R - pow(R * cos(start_angle) + u, 2)) - sqrt(R * R - pow(R * cos(start_angle), 2)));

auto dx = -sin(theta);
auto dy = cos(theta);

Eigen::Matrix4d m = Eigen::Matrix4d::Identity();
m.col(0) = Eigen::Vector4d(dx, dy, 0, 0);
m.col(1) = Eigen::Vector4d(-dy, dx, 0, 0);
m.col(2) = Eigen::Vector4d(0, 0, 1, 0);
m.col(3) = Eigen::Vector4d(0.0/*u*/, y, 0.0, 1.0);
return m;
};
} else if (segment_type_ == ST_CANT) {
else if (segment_type_ == ST_CANT) {
Logger::Warning(std::runtime_error("Use of IfcCircle for cant is not supported"));
eval_ = [](double /*u*/) -> Eigen::Matrix4d { return Eigen::Matrix4d::Identity(); };
} else {
Expand Down

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