Add triangles member for mesh and polygon

nicklockwood · nicklockwood · commit 2d139fa485d3 · 2025-03-29T18:21:38.000Z
diff --git a/ShapeScript/Interpreter.swift b/ShapeScript/Interpreter.swift
@@ -484,7 +484,6 @@ private extension RuntimeError {
         "translation": ["position"],
         "position": ["translate", "bounds", "center"],
         "faces": ["polygons"],
-        "triangles": ["polygons"],
         "vertices": ["points"],
         "scale": ["size"],
         "size": ["scale", "bounds"],
diff --git a/ShapeScript/Members.swift b/ShapeScript/Members.swift
@@ -114,6 +114,7 @@ extension ValueType {
         "count": .number,
         "points": .list(.point),
         "polygons": .list(.polygon),
+        "triangles": .list(.polygon),
         "lines": .list(.string),
         "words": .list(.string),
         "characters": .list(.string),
@@ -177,13 +178,13 @@ extension Value {
         case let .mesh(geometry):
             var members = ["name", "bounds"]
             if geometry.hasMesh {
-                members += ["polygons", "material"]
+                members += ["polygons", "triangles", "material"]
             }
             return members
         case .path:
             return ["bounds", "points"]
         case .polygon:
-            return ["bounds", "center", "points"]
+            return ["bounds", "center", "points", "triangles"]
         case .point:
             return ["x", "y", "z", "position", "color", "isCurved"]
         case .bounds:
@@ -319,6 +320,11 @@ extension Value {
                 let polygons = (geometry.mesh?.polygons ?? [])
                     .transformed(by: geometry.transform)
                 return .tuple(polygons.map { .polygon($0) })
+            case "triangles" where geometry.hasMesh:
+                _ = geometry.build { !isCancelled() }
+                let triangles = (geometry.mesh?.triangulate().polygons ?? [])
+                    .transformed(by: geometry.transform)
+                return .tuple(triangles.map { .polygon($0) })
             case "material" where geometry.hasMesh:
                 return .material(geometry.material)
             default:
@@ -338,6 +344,8 @@ extension Value {
                 return .vector(polygon.center)
             case "points":
                 return .tuple(polygon.vertices.map { .point(PathPoint($0)) })
+            case "triangles":
+                return .tuple(polygon.triangulate().map { .polygon($0) })
             default:
                 return nil
             }
diff --git a/docs/src/expressions.md b/docs/src/expressions.md
@@ -312,14 +312,15 @@ for point in circle.points {
 }
 ```
 
-For [meshes](meshes.md) you can access the `name`, `bounds`, `polygons` and `material` members:
+For [meshes](meshes.md) you can access the `name`, `bounds`, `polygons`, `triangles` and `material` members:
 
 ```swift
 print cube.bounds.size // prints 1 1 1
 print cube.polygons.count // prints 6
+print cube.triangles.count // prints 12
 ```
 
-For [polygons](meshes.md#polygons-and-points) you can get the `bounds` or `center`, or use `points` to access the individual vertices. For points you can access the `position` and `color`:
+For [polygons](meshes.md#polygons-and-points) you can get the `bounds` or `center`, use `triangles` to get the triangles that make up the polygon, or use `points` to access the individual vertices. For points you can access the `position` and `color`:
 
 ```swift
 define triangle polygon {
