Add custom face color calculation function

README.md

@@ -4,7 +4,10 @@ grouping the vertices into one single draw call). It is also a null-safe library
 
 ## Preview
 
-![Failed to load Screenshot](https://github.com/arnovanliere/object_3d/blob/master/screenshot.png)
+![Failed to load Screenshot](./screenshots/screenshot.png)
+![Failed to load Screenshot](./screenshots/fresnel.png)
+See more in [/screenshots](./screenshots/).
 
 ## Credits
 - All credits for the initial library go to [hemanthrajv](https://github.com/hemanthrajv/flutter_3d_obj).
+- Gesture feedback, optimization, and face coloring customization are thanks to [TheMaverickProgrammer](https://github.com/TheMaverickProgrammer) in collaboration with [DBL](https://github.com/InstrinsicAutomations).

analysis_options.yaml

@@ -14,6 +14,21 @@ linter:
     prefer_final_in_for_each: true
     use_build_context_synchronously: true
     always_declare_return_types: true
-    always_specify_types: false
-    omit_local_variable_types: true
-    avoid_types_on_closure_parameters: true
+    always_specify_types: true
+    void_checks: true
+    use_raw_strings: true
+    unnecessary_this: true
+    unnecessary_string_interpolations: true
+    unnecessary_string_escapes: true
+    unnecessary_null_aware_assignments: true
+    unnecessary_new: true
+    unnecessary_late: true
+    unnecessary_lambdas: true
+    unnecessary_brace_in_string_interps: true
+    prefer_asserts_in_initializer_lists: true
+    prefer_asserts_with_message: true
+    lines_longer_than_80_chars: true
+    avoid_setters_without_getters: true
+    avoid_return_types_on_setters: true
+    annotate_overrides: true
+    always_put_required_named_parameters_first: true

example/lib/main.dart

@@ -1,4 +1,6 @@
 import 'package:flutter/material.dart';
+import 'dart:math' as math;
+import 'package:vector_math/vector_math_64.dart' show Vector3;
 import 'package:object_3d/object_3d.dart';
 
 void main() {
@@ -29,16 +31,36 @@ class MyHomePage extends StatefulWidget {
 }
 
 class _MyHomePageState extends State<MyHomePage> {
+  // (uncomment line in Object3D constructor)
+  // ignore: unused_element
+  Face _fresnel(Face face) {
+    final color = Colors.blue;
+    final light = Vector3(0.0, 0.0, 100.0).normalized();
+    double ln1 = light.dot(face.normal);
+    double s1 = 1.0 + face.v1.normalized().dot(face.normal);
+    double s2 = 1.0 + face.v2.normalized().dot(face.normal);
+    double s3 = 1.0 + face.v3.normalized().dot(face.normal);
+    double power = 2;
+
+    Color c = Color.fromRGBO(
+        (color.red + math.pow(s1, power).round()).clamp(0, 255),
+        (color.green + math.pow(s2, power).round()).clamp(0, 255),
+        (color.blue + math.pow(s3, power).round()).clamp(0, 255),
+        1.0 - ln1.abs());
+    return face..setColors(c, c, c);
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Object 3D Example'),
       ),
-      body: const Center(
+      body: Center(
         child: Object3D(
-          size: Size(400.0, 400.0),
+          size: const Size(400.0, 400.0),
           path: "assets/file.obj",
+          //  faceColorFunc: _fresnel, // uncomment to see in action
         ),
       ),
     );