Update to STL Seralizer

Now supports binary and is a little more robust.

Can have a list of meshes passed to it now.

serializers/src/stl/stlSerializer.ts

@@ -8,18 +8,26 @@ import { Vector3 } from "babylonjs/Maths/math";
 export class STLExport {
      /**
      * Exports the geometry of a Mesh array in .STL file format (ASCII)
-     * @param mesh defines the mesh to serialize
-     * @param fileName Name of the file when downloaded.
+     * @param meshes list defines the mesh to serialize
      * @param download triggers the automatic download of the file.
-     * @returns the ASCII STL format
+	 * @param fileName changes the downloads fileName.
+	 * @param binary changes the STL to a binary type.
+     * @returns the STL as UTF8 string
      */
-    public static ASCII(mesh: Mesh, download = false, fileName?: string): string {
-
-            let data = 'solid exportedMesh\r\n';
-            let vertices = mesh.getVerticesData(VertexBuffer.PositionKind) || [];
+    public static CreateSTL(meshes: Mesh[], download:boolean=true, fileName:string='STL_Mesh', binary:boolean=false): any {
+		
+		let data;
+		let multiMesh = false;
+		if(meshes.length>1){multiMesh=true;}
+		if(!binary){
+		data = 'solid exportedMesh\r\n';		
+		for(let i=0; i<meshes.length; i++){
+			let mesh = meshes[i];
+			mesh.bakeCurrentTransformIntoVertices();
+			let vertices = mesh.getVerticesData(VertexBuffer.PositionKind) || [];
             let indices = mesh.getIndices() || [];
-
-            for (let i = 0; i < indices.length; i += 3) {
+			
+			for (let i = 0; i < indices.length; i += 3) {
                 let id = [indices[i] * 3, indices[i + 1] * 3, indices[i + 2] * 3];
                 let v = [
                 new Vector3(vertices[id[0]], vertices[id[0] + 1], vertices[id[0] + 2]),
@@ -37,21 +45,85 @@ export class STLExport {
                 data += '\t\tvertex ' + v[2].x + ' ' + v[2].y + ' ' + v[2].z + '\r\n';
                 data += '\tendloop\r\n';
                 data += 'endfacet\r\n';
-            }
-            data += 'endsolid exportedMesh';
-
-            if (download) {
-                let a = document.createElement('a');
-                let blob = new Blob([data], {'type': 'application/octet-stream'});
-                a.href = window.URL.createObjectURL(blob);
-
-                if (!fileName) {
-                    fileName = "STL_Mesh";
-                }
-                a.download = fileName + ".stl";
-                a.click();
-            }
-
-            return data;
+            }			
+		}		
+		data += 'endsolid exportedMesh';
+		}else{			
+			//Adapted from https://gist.github.com/paulkaplan/6d5f0ab2c7e8fdc68a61
+			
+			//get faceCount
+			let faceCount = 0;
+			for(let i=0; i<meshes.length; i++){
+				let mesh = meshes[i];
+				faceCount += mesh.getIndices().length;			
+			}
+			
+			let isLittleEndian = true;
+			
+			let bufferSize = 84 + (50 * faceCount);
+			let buffer = new ArrayBuffer(bufferSize);			
+			data = new DataView(buffer);
+			let offset = 0;			
+			
+			let writeVector = function(dataview:any, offset:number, vector:Vector3, isLittleEndian:boolean){
+				offset = writeFloat(dataview, offset, vector.x, isLittleEndian);
+				offset = writeFloat(dataview, offset, vector.y, isLittleEndian);
+				return writeFloat(dataview, offset, vector.z, isLittleEndian);
+			};
+
+			let writeFloat = function(dataview:any, offset:number, value:number, isLittleEndian:boolean) {
+				dataview.setFloat32(offset, value, isLittleEndian);
+				return offset + 4;
+			};
+			
+			//Allow later for binary Messages to be passed in the header for now offset by 80.
+			offset += 80;			
+			data.setUint32(offset, faceCount, isLittleEndian);
+			offset += 4;			
+
+			for(let i=0; i<meshes.length; i++){
+				let mesh = meshes[i];
+				mesh.bakeCurrentTransformIntoVertices();
+				let vertices = mesh.getVerticesData(VertexBuffer.PositionKind) || [];
+				let indices = mesh.getIndices() || [];
+			
+				for (let i = 0; i < indices.length; i += 3) {
+					let id = [indices[i] * 3, indices[i + 1] * 3, indices[i + 2] * 3];
+					let v = [
+					new Vector3(vertices[id[0]], vertices[id[0] + 1], vertices[id[0] + 2]),
+					new Vector3(vertices[id[1]], vertices[id[1] + 1], vertices[id[1] + 2]),
+					new Vector3(vertices[id[2]], vertices[id[2] + 1], vertices[id[2] + 2])
+					];
+					let p1p2 = v[0].subtract(v[1]);
+					let p3p2 = v[2].subtract(v[1]);
+					let n = (Vector3.Cross(p1p2, p3p2)).normalize();
+
+					offset = writeVector(data, offset, n, isLittleEndian);
+					offset = writeVector(data, offset, v[0], isLittleEndian);
+					offset = writeVector(data, offset, v[1], isLittleEndian);
+					offset = writeVector(data, offset, v[2], isLittleEndian);
+					offset += 2;
+				}		
+			}			
+		
+		}	
+
+        if (download) {
+			let a = document.createElement('a');
+			let blob = new Blob([data], {'type': 'application/octet-stream'});
+			a.href = window.URL.createObjectURL(blob);
+
+			if (!fileName) {
+				fileName = "STL_Mesh";
+			}
+			a.download = fileName + ".stl";
+			a.click();
+		}
+
+		/*if(binary){
+			return String.fromCharCode.apply(null, new Uint16Array(data));
+		}*/
+		
+        return data;
     }
-}
+}