From 88c73ca3289410f4de29b3585166c2bacb6c2891 Mon Sep 17 00:00:00 2001
From: Marian <mail@marian42.de>
Date: Sat, 10 Feb 2024 21:46:31 +0000
Subject: [PATCH] Add a helper function to get a vector on a triangle edge

---
 src/export/STLExporter.ts | 44 +++++++++++++++++++--------------------
 src/geometry/Triangle.ts  | 14 ++++++++++++-
 2 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/src/export/STLExporter.ts b/src/export/STLExporter.ts
index a6d30cc..eb80e95 100644
--- a/src/export/STLExporter.ts
+++ b/src/export/STLExporter.ts
@@ -95,45 +95,45 @@ class STLExporter {
 
             for (var i = 0; i < edge1Hits.length - 1; i++) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[i]),
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[i + 1]),
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[edge3Hits.length - 1])
+                    triangle.getOnEdge1(edge1Hits[i]),
+                    triangle.getOnEdge1(edge1Hits[i + 1]),
+                    triangle.getOnEdge3(edge3Hits[edge3Hits.length - 1])
                 ));
             }
             for (var i = 0; i < edge2Hits.length - 1; i++) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[i]),
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[i + 1]),
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[edge1Hits.length - 1])
+                    triangle.getOnEdge2(edge2Hits[i]),
+                    triangle.getOnEdge2(edge2Hits[i + 1]),
+                    triangle.getOnEdge1(edge1Hits[edge1Hits.length - 1])
                 ));
             }
             for (var i = 0; i < edge3Hits.length - 1; i++) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[i]),
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[i + 1]),
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[edge2Hits.length - 1])
-                ))
+                    triangle.getOnEdge3(edge3Hits[i]),
+                    triangle.getOnEdge3(edge3Hits[i + 1]),
+                    triangle.getOnEdge2(edge2Hits[edge2Hits.length - 1])
+                ));
             }
             if (edge1Hits.length > 1 && edge2Hits.length == 1) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[edge1Hits.length - 1]),
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[0]),
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[edge3Hits.length - 1]),
-                ))
+                    triangle.getOnEdge1(edge1Hits[edge1Hits.length - 1]),
+                    triangle.getOnEdge2(edge2Hits[0]),
+                    triangle.getOnEdge3(edge3Hits[edge3Hits.length - 1])
+                ));
             }
             else if (edge2Hits.length > 1 && edge3Hits.length == 1) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[edge2Hits.length - 1]),
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[0]),
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[edge1Hits.length - 1]),
-                ))
+                    triangle.getOnEdge2(edge2Hits[edge2Hits.length - 1]),
+                    triangle.getOnEdge3(edge3Hits[0]),
+                    triangle.getOnEdge1(edge1Hits[edge1Hits.length - 1])
+                ));
             }
             else if (edge3Hits.length > 1 && edge1Hits.length == 1) {
                 result.push(new Triangle(
-                    Vector3.interpolate(triangle.v3, triangle.v1, edge3Hits[edge3Hits.length - 1]),
-                    Vector3.interpolate(triangle.v1, triangle.v2, edge1Hits[0]),
-                    Vector3.interpolate(triangle.v2, triangle.v3, edge2Hits[edge2Hits.length - 1]),
-                ))
+                    triangle.getOnEdge3(edge3Hits[edge3Hits.length - 1]),
+                    triangle.getOnEdge1(edge1Hits[0]),
+                    triangle.getOnEdge2(edge2Hits[edge2Hits.length - 1])
+                ));
             }
         }
 
diff --git a/src/geometry/Triangle.ts b/src/geometry/Triangle.ts
index dfad3d6..14a3bb0 100644
--- a/src/geometry/Triangle.ts
+++ b/src/geometry/Triangle.ts
@@ -15,7 +15,19 @@ class Triangle {
         }
     }
 
-    normal(): Vector3 {
+    public normal(): Vector3 {
         return this.v3.minus(this.v1).cross(this.v2.minus(this.v1)).normalized();
     }
+
+    public getOnEdge1(progress: number): Vector3 {
+        return Vector3.interpolate(this.v1, this.v2, progress);
+    }
+
+    public getOnEdge2(progress: number): Vector3 {
+        return Vector3.interpolate(this.v2, this.v3, progress);
+    }
+    
+    public getOnEdge3(progress: number): Vector3 {
+        return Vector3.interpolate(this.v3, this.v1, progress);
+    }
 }
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