Mesh closest point by Sophielelerre · Pull Request #420 · GSharker/G-Shark

Sophielelerre · 2023-07-20T13:40:11Z

What type of PR is this? (check all applicable)

Description

This PR adds a ClosestPoint() implementation for meshes. The method takes a mesh and a test point and returns the closest point to the test point on the mesh. The algorithm finds the closest point to all the faces, then the absolute closest. This point can be either on a mesh vertex, mesh edge, or inside a mesh face. The method can be used with triangle meshes, quad meshes, and Ngon meshes. Any Ngons faces are triangulated using vertices' centroid and consecutive vertices. Quads are treated as Ngons. I did not work on the tests yet, I'd like some feedback first.

Related Tickets & Documents

Please use this format link issue numbers: Fixes #416
#416 (comment)

Added tests?

👍 yes
🙅 no, because they aren't needed
🙋 no, because I need help

Added to documentation?

📓 docs
🙅 no documentation needed

2) Added a loop in the CloudClosestPoint instead of the IndexOf(Min()) method 3) Added an if statement to distiguish triangular faces and/or quad faces in the Mesh class

- from lists to arrays - code refinements - addition of polygon option (fan strategy)

Ngon doesn't get detected

…nds + a message

…3 class) - added Ngon implementation (stellate method) (Notice: the vertices of the Ngon are being converted to Point3. Can't index a IEnumerable instead of a list)

Added Docstrings for all methods. Quad analysed as Ngon. Cloud closest point now static method.

Co-authored-by: iltabe <64929000+iltabe@users.noreply.github.com>

d3ssy

Thank you for this contribution! Please check comments and update code accordingly. Mostly cosmetic and readibility comments.

Please also add the relevant unit tests in the appropriate test classes for the new methods. For closest point methods edge and point coincidence edge cases will be important to include.

There is also another PR open for PointInPolygon which may or may not be useful. #419

d3ssy · 2023-08-07T13:30:07Z

+        /// <param name="trianglePoints">Triangle vertices.</param>
+        /// <returns>Boolean result (In - True , Out - False).</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when trianglePoints is not 3 points.</exception>
+        private bool IsPointInTriangle(Point3 projection, Point3[] trianglePoints)


Could take in a Polygon and check it has three vertices instead of an array of Point3.

If you keep array as input, do you need to check the three points for collinearity?

Rename input args to point and triangle for clarity

What happens with coincident points with an edge? Are they in or out?

d3ssy · 2023-08-07T13:30:27Z

        }

+        /// <summary>
+        /// Checks if point is in or out a triangle.


inside or outside of a triangle

d3ssy · 2023-08-07T13:32:55Z

+        /// <param name="point">Test point.</param>
+        /// <returns>Closest point to the triangle.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when trianglePoints is not 3 points.</exception>
+        private Point3 ClosestPointToTriangle(Point3[] trianglePoints, Point3 point)


ClosestPoint is fine as method name on Mesh, trianglular polygon implied by input args

Same comments regarding Polygon input vs point array as above

Same comments regarding naming

d3ssy · 2023-08-07T13:34:01Z

+        }
+
+        /// <summary>
+        /// Finds the closest point to a mesh.


A bit more detail to differentiate the different ClosestPoint methods would be helpful in the summary docstring

d3ssy · 2023-08-07T13:35:21Z

+                        Point3 ClosestPointToNgon = ClosestPointToTriangle(trianglePoints, point);
+                        TrianglesCP.Add(ClosestPointToNgon);
+                    }
+                    Point3 ClosestPoint = Point3.CloudClosestPoint(TrianglesCP, point);


lowercase for vars

d3ssy · 2023-08-07T13:35:27Z

+                {
+                    // Ngon triangulation using the vertices' centroid and consecutive vertices to create the triangles 
+                    Point3 ngonCentre = Point3.AveragePoint(faceVertices);
+                    var TrianglesCP = new List<Point3>();


lowercase for vars

d3ssy · 2023-08-07T13:35:37Z

+            List<MeshVertex> meshVertices = Vertices;
+            // All faces check 
+            IEnumerable<MeshFace> allFaces = this.Faces;
+            var closerPointToFaceList = new List<Point3>();


closer or closest?

d3ssy · 2023-08-07T13:35:54Z

+                    for (int i = 0; i < faceVertices .Count; i++)
+                    {
+                        Point3[] trianglePoints = new Point3[] { ngonCentre, faceVertices[i], faceVertices[(i + 1)% faceVertices.Count] };
+                        Point3 ClosestPointToNgon = ClosestPointToTriangle(trianglePoints, point);


lowercase for vars

d3ssy · 2023-08-07T13:38:50Z

+        /// </summary>
+        /// <param name="points"></param>
+        /// <returns>The average point.</returns>
+        public static Point3 AveragePoint (IEnumerable<Point3> points)


Already implemented as Centroid() method in Point3

G-Shark/src/GShark/Geometry/Point3.cs

Line 520 in 76819e0

public static Point3 Centroid(IEnumerable<Point3> points)

d3ssy · 2023-08-07T13:43:13Z

+        }
+
+        /// <summary>
+        /// Finds closest point to a test point from a cloud of points.


This should be moved to Point3 class as Point3.ClosestPoint(Point3[] points, Point3 testPoint). I don't think the "cloud" terminology is useful here as we do not have a specialized PointCloud class.

Sophielelerre and others added 19 commits July 3, 2023 15:59

added test function MeshClosestPoint

1eb36ba

Added Mesh Closest Point Implementation in the Mesh class

94b7b1b

1) Moved the CloudClosestPoint method to the Point3 class

c1209af

2) Added a loop in the CloudClosestPoint instead of the IndexOf(Min()) method 3) Added an if statement to distiguish triangular faces and/or quad faces in the Mesh class

Implemented for Ngons (returns the closest vertex)

e23d9b9

- formatting changes

a509dd3

- from lists to arrays - code refinements - addition of polygon option (fan strategy)

Checking all faces fixes the bug regarding the point on the wrong face

7306376

else if correction

9f04c4b

Ngon doesn't get detected

Ngon detected in the RhinoCommand and then given as triangles and qua…

336eb2d

…nds + a message

deleted comment on Rhino

62dd7d6

added mid point function in point3 class

9c9cc20

- mid point function in mesh class (doesn't find it if I put in point…

1092fc2

…3 class) - added Ngon implementation (stellate method) (Notice: the vertices of the Ngon are being converted to Point3. Can't index a IEnumerable instead of a list)

version working with Ngons (stellate method)

23f92da

moved Average point method to the Point3 class

981ab30

% operator in the stellate method

769ce65

work in progress

29b2b2b

No more MeshVertex to Point3 conversion.

bf9fbfb

Added Docstrings for all methods. Quad analysed as Ngon. Cloud closest point now static method.

the same object within the cloud without copying it comment added

3b844dd

Minor formatting changes.

76a4cfd

Update src/GShark/Geometry/Mesh.cs

8717512

Co-authored-by: iltabe <64929000+iltabe@users.noreply.github.com>

d3ssy requested changes Aug 7, 2023

View reviewed changes

sonomirco added enhancement 📢 Issues describing an enhancement or pull requests adding an enhancement. minor Pull requests requiring a minor version update according to semantic versioning. labels Aug 13, 2023

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Mesh closest point - #420

Mesh closest point#420
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Sophielelerre commented Jul 20, 2023

What type of PR is this? (check all applicable)

Description

Related Tickets & Documents

Added tests?

Added to documentation?

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