Merge materials when importing obj mesh

Sources/arm/io/ImportObj.hx

@@ -27,11 +27,55 @@ class ImportObj {
 				}
 			}
 			else {
+				var parts: Array<ObjParser> = [];
 				var obj = new ObjParser(b);
-				ImportMesh.makeMesh(obj, path);
+				parts.push(obj);
 				while (obj.hasNext) {
 					obj = new ObjParser(b, obj.pos);
-					ImportMesh.addMesh(obj);
+					parts.push(obj);
+				}
+				if (Context.splitBy == SplitMaterial) {
+					// Merge to single object per material
+					for (i in 0...parts.length) {
+						var j = i + 1;
+						while (j < parts.length) {
+							if (parts[i].name == parts[j].name) {
+								var posa0 = parts[i].posa;
+								var posa1 = parts[j].posa;
+								var nora0 = parts[i].nora;
+								var nora1 = parts[j].nora;
+								var texa0 = parts[i].texa != null ? parts[i].texa : null;
+								var texa1 = parts[j].texa != null ? parts[j].texa : null;
+								var inda0 = parts[i].inda;
+								var inda1 = parts[j].inda;
+								var posa = new kha.arrays.Int16Array(posa0.length + posa1.length);
+								var nora = new kha.arrays.Int16Array(nora0.length + nora1.length);
+								var texa = (texa0 != null && texa1 != null) ? new kha.arrays.Int16Array(texa0.length + texa1.length) : null;
+								var inda = new kha.arrays.Uint32Array(inda0.length + inda1.length);
+								var voff = Std.int(posa0.length / 4);
+								untyped __js__("posa.set(posa0)");
+								untyped __js__("posa.set(posa1, posa0.length)");
+								untyped __js__("nora.set(nora0)");
+								untyped __js__("nora.set(nora1, nora0.length)");
+								if (texa != null) {
+									untyped __js__("texa.set(texa0)");
+									untyped __js__("texa.set(texa1, texa0.length)");
+								}
+								untyped __js__("inda.set(inda0)");
+								for (k in 0...inda1.length) inda[k + inda0.length] = inda1[k] + voff;
+								parts[i].posa = posa;
+								parts[i].nora = nora;
+								parts[i].texa = texa;
+								parts[i].inda = inda;
+								parts.splice(j, 1);
+							}
+							else j++;
+						}
+					}
+				}
+				ImportMesh.makeMesh(parts[0], path);
+				for (i in 1...parts.length) {
+					ImportMesh.addMesh(parts[i]);
 				}
 			}
 			Data.deleteBlob(path);