Revert "Take average of point-on-line projections instead of intersection of outer lines."

This reverts commit 58eaae887e04cc7f699efb0735b193d4b8f55b8b.

Author: rburema

src/utils/linearAlg2D.h

@@ -92,12 +92,6 @@ class LinearAlg2D
         return true;
     }
 
-    inline static Point projectPointOnLine(const Point& p, const Point& a, const Point& b)
-    {
-        const Point vec = b - a;
-        return a + ((dot(p - a, vec) * vec) / vSize2(vec));
-    }
-
     /*!
      * Find whether a point projected on a line segment would be projected to
      * - properly on the line : zero returned

src/utils/polygon.cpp

@@ -390,15 +390,14 @@ void PolygonRef::simplify(const coord_t smallest_line_segment_squared, const coo
             {
                 // Special case; The next line is long. If we were to remove this, it could happen that we get quite noticeable artifacts.
                 // We should instead move this point to a location where both edges are kept and then remove the previous point that we wanted to keep.
-                // By taking the average of the projections of the original points on the outer lines, we get a point that mostly preserves the direction (so it makes the corner a bit more pointy).
+                // By taking the intersection of these two lines, we get a point that preserves the direction (so it makes the corner a bit more pointy).
                 // We just need to be sure that the intersection point does not introduce an artifact itself.
-                const Point mid = (previous + current) / 2;
-                const Point a = LinearAlg2D::projectPointOnLine(mid, previous_previous, previous);
-                const Point b = LinearAlg2D::projectPointOnLine(mid, current, next);
-                const Point intersection_point = (a + b) / 2;
-                if (LinearAlg2D::getDist2FromLine(intersection_point, previous, current) > allowed_error_distance_squared
-                     || vSize2(intersection_point - previous) > smallest_line_segment_squared  // The intersection point is way too far from the 'previous'
-                     || vSize2(intersection_point - next) > smallest_line_segment_squared)     // and 'next' points, so it shouldn't replace 'current'
+                Point intersection_point;
+                bool has_intersection = LinearAlg2D::lineLineIntersection(previous_previous, previous, current, next, intersection_point);
+                if (!has_intersection
+                    || LinearAlg2D::getDist2FromLine(intersection_point, previous, current) > allowed_error_distance_squared
+                    || vSize2(intersection_point - previous) > smallest_line_segment_squared  // The intersection point is way too far from the 'previous'
+                    || vSize2(intersection_point - next) > smallest_line_segment_squared)     // and 'next' points, so it shouldn't replace 'current'
                 {
                     // We can't find a better spot for it, but the size of the line is more than 5 micron.
                     // So the only thing we can do here is leave it in...