Ported point_along_segment(), Polyline::length(), Polyline::clip_end() to XS

xs/src/Line.cpp

@@ -42,6 +42,18 @@ Line::midpoint() const
     return new Point ((this->a.x + this->b.x) / 2.0, (this->a.y + this->b.y) / 2.0);
 }
 
+Point*
+Line::point_at(double distance) const
+{
+    double len = this->length();
+    Point* p = new Point(this->a);
+    if (this->a.x != this->b.x)
+        p->x = this->a.x + (this->b.x - this->a.x) * distance / len;
+    if (this->a.y != this->b.y)
+        p->y = this->a.y + (this->b.y - this->a.y) * distance / len;
+    return p;
+}
+
 #ifdef SLIC3RXS
 void
 Line::from_SV(SV* line_sv)

xs/src/Line.hpp

@@ -19,6 +19,7 @@ class Line
     void reverse();
     double length() const;
     Point* midpoint() const;
+    Point* point_at(double distance) const;
     
     #ifdef SLIC3RXS
     void from_SV(SV* line_sv);

xs/src/MultiPoint.cpp

@@ -38,6 +38,17 @@ MultiPoint::first_point() const
     return new Point(this->points.front());
 }
 
+double
+MultiPoint::length() const
+{
+    Lines lines = this->lines();
+    double len = 0;
+    for (Lines::iterator it = lines.begin(); it != lines.end(); ++it) {
+        len += it->length();
+    }
+    return len;
+}
+
 #ifdef SLIC3RXS
 void
 MultiPoint::from_SV(SV* poly_sv)

xs/src/MultiPoint.hpp

@@ -1,6 +1,7 @@
 #ifndef slic3r_MultiPoint_hpp_
 #define slic3r_MultiPoint_hpp_
 
+#include "Line.hpp"
 #include "Point.hpp"
 #include <algorithm>
 #include <vector>
@@ -17,6 +18,8 @@ class MultiPoint
     void reverse();
     Point* first_point() const;
     virtual Point* last_point() const = 0;
+    virtual Lines lines() const = 0;
+    double length() const;
     
     #ifdef SLIC3RXS
     void from_SV(SV* poly_sv);

xs/src/Polyline.cpp

@@ -19,6 +19,27 @@ Polyline::lines() const
     return lines;
 }
 
+// removes the given distance from the end of the polyline
+void
+Polyline::clip_end(double distance)
+{
+    while (distance > 0) {
+        Point last_point = *this->last_point();
+        this->points.pop_back();
+        if (this->points.empty()) break;
+        
+        double last_segment_length = last_point.distance_to(this->last_point());
+        if (last_segment_length <= distance) {
+            distance -= last_segment_length;
+            continue;
+        }
+        
+        Line segment(last_point, *this->last_point());
+        this->points.push_back(*segment.point_at(distance));
+        distance = 0;
+    }
+}
+
 #ifdef SLIC3RXS
 SV*
 Polyline::to_SV_ref()

xs/src/Polyline.hpp

@@ -10,6 +10,7 @@ class Polyline : public MultiPoint {
     public:
     Point* last_point() const;
     Lines lines() const;
+    void clip_end(double distance);
     
     #ifdef SLIC3RXS
     SV* to_SV_ref();