feat: allow controlling when a fixture is rendered (#1648)

Changes _renderFixtures to renderFixture. This keeps the consistency with the other public render methods in BodyComponent.

Introduces new functionalities:

Allow listening when a given fixture is rendered

Allows modifying the rendering logic for a given (one or more) fixtures.

For example, avoiding a fixture to be rendered:

class MyBodyComponent extends BodyComponent { ... void renderFixture(Canvas canvas, Fixture fixture) { final avoidRendering = condition; // Any condition here. if (avoidRendering) return; super.renderFixture(canvas, fixture); } ... }

packages/flame_forge2d/lib/body_component.dart

@@ -27,7 +27,7 @@ abstract class BodyComponent<T extends Forge2DGame> extends Component
  /// Specifies if the body's fixtures should be rendered.
  ///
  /// [renderBody] is true by default for [BodyComponent], if set to false
- /// the body wont be rendered.
+ /// the body's fixtures wont be rendered.
  ///
  /// If you render something on top of the [BodyComponent], or doesn't want it
  /// to be seen, you probably want to set it to false.
@@ -73,32 +73,45 @@ abstract class BodyComponent<T extends Forge2DGame> extends Component
  @override
  void render(Canvas canvas) {
  if (renderBody) {
- _renderFixtures(canvas);
+ body.fixtures.forEach(
+ (fixture) => renderFixture(canvas, fixture),
+ );
  }
  }
 
  @override
  void renderDebugMode(Canvas canvas) {
- _renderFixtures(canvas);
+ body.fixtures.forEach(
+ (fixture) => renderFixture(canvas, fixture),
+ );
  }
 
- void _renderFixtures(Canvas canvas) {
+ /// Renders a [Fixture] in a [Canvas].
+ ///
+ /// Called for each fixture in [body] when [render]ing. Override this method
+ /// to customize how fixtures are rendered. For example, you can filter out
+ /// fixtures that you don't want to render.
+ ///
+ /// **NOTE**: If [renderBody] is false, no fixtures will be rendered. Hence,
+ /// [renderFixture] is not called when [render]ing.
+ void renderFixture(
+ Canvas canvas,
+ Fixture fixture,
+ ) {
  canvas.save();
- for (final fixture in body.fixtures) {
- switch (fixture.type) {
- case ShapeType.chain:
- _renderChain(canvas, fixture);
- break;
- case ShapeType.circle:
- _renderCircle(canvas, fixture);
- break;
- case ShapeType.edge:
- _renderEdge(canvas, fixture);
- break;
- case ShapeType.polygon:
- _renderPolygon(canvas, fixture);
- break;
- }
+ switch (fixture.type) {
+ case ShapeType.chain:
+ _renderChain(canvas, fixture);
+ break;
+ case ShapeType.circle:
+ _renderCircle(canvas, fixture);
+ break;
+ case ShapeType.edge:
+ _renderEdge(canvas, fixture);
+ break;
+ case ShapeType.polygon:
+ _renderPolygon(canvas, fixture);
+ break;
  }
  canvas.restore();
  }

packages/flame_forge2d/lib/forge2d_camera.dart

@@ -1,8 +1,7 @@
 import 'package:flame/components.dart';
 import 'package:flame/extensions.dart';
 import 'package:flame/game.dart';
-
-import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:flame_forge2d/body_component.dart';
 
 extension Forge2DCameraExtension on Camera {
  /// Immediately snaps the camera to start following the [BodyComponent].

packages/flame_forge2d/pubspec.yaml

@@ -9,12 +9,15 @@ environment:
 
 dependencies:
  flame: ^1.1.1
- forge2d: ">=0.11.0 <0.12.0"
  flutter:
  sdk: flutter
+ forge2d: ">=0.11.0 <0.12.0"
 
 dev_dependencies:
  dartdoc: ^4.1.0
  flame_lint: ^0.0.1
+ flutter_test:
+ sdk: flutter
+ flame_test: ^1.4.0
  mocktail: ^0.3.0
  test: any

packages/flame_forge2d/test/body_component_test.dart

@@ -1,23 +1,232 @@
-import 'package:flame_forge2d/body_component.dart';
-import 'package:test/expect.dart';
-import 'package:test/scaffolding.dart';
+import 'dart:ui';
+
+import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:flame_test/flame_test.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+
+class _TestBodyComponent extends BodyComponent {
+ @override
+ Body createBody() => body;
 
-class TestBodyComponent extends BodyComponent {
  @override
  void noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
+class _MockCanvas extends Mock implements Canvas {}
+
 void main() {
+ TestWidgetsFlutterBinding.ensureInitialized();
+
  group('BodyComponent', () {
  group('renderBody', () {
  test('is true by default', () {
- final body = TestBodyComponent();
- expect(body.renderBody, isTrue);
+ final component = _TestBodyComponent();
+ expect(component.renderBody, isTrue);
  });
 
  test('sets and gets', () {
- final body = TestBodyComponent()..renderBody = false;
- expect(body.renderBody, isFalse);
+ final component = _TestBodyComponent()..renderBody = false;
+ expect(component.renderBody, isFalse);
+ });
+ });
+
+ group('render', () {
+ group('draws correctly', () {
+ String goldenPath(String name) => 'goldens/body_component/$name.png';
+
+ final flameTester = FlameTester(Forge2DGame.new);
+ final testPaint = Paint()..color = const Color(0xffff0000);
+
+ flameTester.testGameWidget(
+ 'a CircleShape',
+ setUp: (game, tester) async {
+ final body = game.world.createBody(BodyDef());
+ final shape = CircleShape()..radius = 5;
+ body.createFixture(FixtureDef(shape));
+
+ final component = _TestBodyComponent()
+ ..body = body
+ ..paint = testPaint;
+ await game.add(component);
+
+ game.camera.followVector2(Vector2.zero());
+ },
+ verify: (game, tester) async {
+ await expectLater(
+ find.byGame<Forge2DGame>(),
+ matchesGoldenFile(goldenPath('circle_shape')),
+ );
+ },
+ );
+
+ flameTester.testGameWidget(
+ 'an EdgeShape',
+ setUp: (game, tester) async {
+ final body = game.world.createBody(BodyDef());
+ final shape = EdgeShape()
+ ..set(
+ Vector2.zero(),
+ Vector2.all(10),
+ );
+ body.createFixture(FixtureDef(shape));
+
+ final component = _TestBodyComponent()
+ ..body = body
+ ..paint = testPaint;
+ await game.add(component);
+
+ game.camera.followVector2(Vector2.zero());
+ },
+ verify: (game, tester) async {
+ await expectLater(
+ find.byGame<Forge2DGame>(),
+ matchesGoldenFile(goldenPath('edge_shape')),
+ );
+ },
+ );
+
+ flameTester.testGameWidget(
+ 'a PolygonShape',
+ setUp: (game, tester) async {
+ final body = game.world.createBody(BodyDef());
+ final shape = PolygonShape()
+ ..set(
+ [
+ Vector2.zero(),
+ Vector2.all(10),
+ Vector2(0, 10),
+ ],
+ );
+ body.createFixture(FixtureDef(shape));
+
+ final component = _TestBodyComponent()
+ ..body = body
+ ..paint = testPaint;
+ await game.add(component);
+
+ game.camera.followVector2(Vector2.zero());
+ },
+ verify: (game, tester) async {
+ await expectLater(
+ find.byGame<Forge2DGame>(),
+ matchesGoldenFile(goldenPath('polygon_shape')),
+ );
+ },
+ );
+
+ flameTester.testGameWidget(
+ 'a ChainShape',
+ setUp: (game, tester) async {
+ final body = game.world.createBody(BodyDef());
+ final shape = ChainShape()
+ ..createChain(
+ [
+ Vector2.zero(),
+ Vector2.all(10),
+ Vector2(10, 0),
+ ],
+ );
+ body.createFixture(FixtureDef(shape));
+
+ final component = _TestBodyComponent()
+ ..body = body
+ ..paint = testPaint;
+ await game.add(component);
+
+ game.camera.followVector2(Vector2.zero());
+ },
+ verify: (game, tester) async {
+ await expectLater(
+ find.byGame<Forge2DGame>(),
+ matchesGoldenFile(goldenPath('chain_shape')),
+ );
+ },
+ );
+ });
+ });
+
+ group('renderFixture', () {
+ group('returs normally', () {
+ late Canvas canvas;
+ late Body body;
+
+ setUp(() {
+ canvas = _MockCanvas();
+ final world = World();
+ body = world.createBody(BodyDef());
+ });
+
+ test('when rendering a CircleShape', () {
+ final component = _TestBodyComponent();
+ final shape = CircleShape()..radius = 5;
+ final fixture = body.createFixture(
+ FixtureDef(shape),
+ );
+
+ expect(
+ () => component.renderFixture(canvas, fixture),
+ returnsNormally,
+ );
+ });
+
+ test('when rendering an EdgeShape', () {
+ final component = _TestBodyComponent();
+ final shape = EdgeShape()
+ ..set(
+ Vector2.zero(),
+ Vector2.all(10),
+ );
+ final fixture = body.createFixture(
+ FixtureDef(shape),
+ );
+
+ expect(
+ () => component.renderFixture(canvas, fixture),
+ returnsNormally,
+ );
+ });
+
+ test('when rendering a PolygonShape', () {
+ final component = _TestBodyComponent();
+ final shape = PolygonShape()
+ ..set(
+ [
+ Vector2.zero(),
+ Vector2.all(10),
+ Vector2(0, 10),
+ ],
+ );
+ final fixture = body.createFixture(
+ FixtureDef(shape),
+ );
+
+ expect(
+ () => component.renderFixture(canvas, fixture),
+ returnsNormally,
+ );
+ });
+
+ test('when rendering a ChainShape', () {
+ final component = _TestBodyComponent();
+ final shape = ChainShape()
+ ..createChain(
+ [
+ Vector2.zero(),
+ Vector2.all(10),
+ Vector2(10, 0),
+ ],
+ );
+ final fixture = body.createFixture(
+ FixtureDef(shape),
+ );
+
+ expect(
+ () => component.renderFixture(canvas, fixture),
+ returnsNormally,
+ );
+ });
  });
  });
  });