Fix simplify to not introduce artifacts

When the intersection point (I) is generated, it may end up being far away from the previous (P)
and next (N) points, even though it satisfies the condition of having a small vertical distance
from the previous(P)-current(C) segment.

This commit fixes that by also checking whether the distance I-P and I-C are also smaller than
the smallest_line_segment provided by the user. If these distances are bigger than that, then the
intersection point (I) should not replace the current point (C) and C should remain inside the
path.

CURA-7709

Author: konskarm

src/utils/polygon.cpp

@@ -350,7 +350,6 @@ void PolygonRef::simplify(const coord_t smallest_line_segment_squared, const coo
         {
             next = path->at((point_idx + 1) % size());
         }
-
         const coord_t removed_area_next = current.X * next.Y - current.Y * next.X; // Twice the Shoelace formula for area of polygon per line segment.
         const coord_t negative_area_closing = next.X * previous.Y - next.Y * previous.X; // area between the origin and the short-cutting segment
         accumulated_area_removed += removed_area_next;
@@ -386,11 +385,14 @@ 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 intersection of these two lines, we get a point that perseves 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.
                 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)
+                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'
                 {
                     if(length2 < 25)
                     {
@@ -404,7 +406,6 @@ void PolygonRef::simplify(const coord_t smallest_line_segment_squared, const coo
                 {
                     // New point seems like a valid one.
                     current = intersection_point;
-                    
                     // If there was a previous point added, remove it.
                     if(new_path.size() > 0)
                     {
@@ -417,7 +418,6 @@ void PolygonRef::simplify(const coord_t smallest_line_segment_squared, const coo
                 continue; //Remove the vertex.
             }
         }
-
         //Don't remove the vertex.
         accumulated_area_removed = removed_area_next; // so that in the next iteration it's the area between the origin, [previous] and [current]
         previous_previous = previous;