feat!: Make resource creation be on demand to enable testing

packages/flame_3d/lib/src/resources/light/light.dart

@@ -17,7 +17,10 @@ class Light extends Resource<void> {
   Light({
     required this.transform,
     required this.source,
-  }) : super(null);
+  });
+
+  @override
+  void createResource() {}
 
   void apply(int index, Shader shader) {
     shader.setVector3('Light$index.position', transform.position);

packages/flame_3d/lib/src/resources/material/material.dart

@@ -12,41 +12,28 @@ abstract class Material extends Resource<gpu.RenderPipeline> {
     required Shader vertexShader,
     required Shader fragmentShader,
   })  : _vertexShader = vertexShader,
-        _fragmentShader = fragmentShader,
-        super(
-          gpu.gpuContext.createRenderPipeline(
-            vertexShader.compile().resource,
-            fragmentShader.compile().resource,
-          ),
-        );
+        _fragmentShader = fragmentShader;
 
   @override
-  gpu.RenderPipeline get resource {
-    var resource = super.resource;
-    if (_recreateResource) {
-      resource = super.resource = gpu.gpuContext.createRenderPipeline(
-        _vertexShader.compile().resource,
-        _fragmentShader.compile().resource,
-      );
-      _recreateResource = false;
-    }
-    return resource;
+  gpu.RenderPipeline createResource() {
+    return gpu.gpuContext.createRenderPipeline(
+      _vertexShader.compile().resource,
+      _fragmentShader.compile().resource,
+    );
   }
 
-  bool _recreateResource = false;
-
   Shader get vertexShader => _vertexShader;
   Shader _vertexShader;
   set vertexShader(Shader shader) {
     _vertexShader = shader;
-    _recreateResource = true;
+    recreateResource = true;
   }
 
   Shader get fragmentShader => _fragmentShader;
   Shader _fragmentShader;
   set fragmentShader(Shader shader) {
     _fragmentShader = shader;
-    _recreateResource = true;
+    recreateResource = true;
   }
 
   void bind(GraphicsDevice device) {}

packages/flame_3d/lib/src/resources/mesh/mesh.dart

@@ -11,9 +11,7 @@ import 'package:flame_3d/resources.dart';
 /// {@endtemplate}
 class Mesh extends Resource<void> {
   /// {@macro mesh}
-  Mesh()
-      : _surfaces = [],
-        super(null);
+  Mesh() : _surfaces = [];
 
   final List<Surface> _surfaces;
   Aabb3? _aabb;
@@ -32,6 +30,9 @@ class Mesh extends Resource<void> {
     }
   }
 
+  @override
+  void createResource() {}
+
   /// The total surface count of the mesh.
   int get surfaceCount => _surfaces.length;
 

packages/flame_3d/lib/src/resources/mesh/surface.dart

@@ -23,7 +23,7 @@ class Surface extends Resource<gpu.DeviceBuffer?> {
      * If `true`, the normals will be calculated if they are not provided.
      */
     bool calculateNormals = true,
-  }) : super(null) {
+  }) {
     final normalizedVertices = _normalize(
       vertices: vertices,
       indices: indices,
@@ -61,25 +61,27 @@ class Surface extends Resource<gpu.DeviceBuffer?> {
   int get indexCount => _indexCount;
   late int _indexCount;
 
+  int? resourceSizeInByes;
+
   @override
-  gpu.DeviceBuffer? get resource {
-    var resource = super.resource;
+  bool get recreateResource {
     final sizeInBytes = _vertices.lengthInBytes + _indices.lengthInBytes;
-    if (resource?.sizeInBytes != sizeInBytes) {
-      // Store the device buffer in the resource parent.
-      resource = super.resource = gpu.gpuContext.createDeviceBuffer(
-        gpu.StorageMode.hostVisible,
-        sizeInBytes,
-      );
+    return resourceSizeInByes != sizeInBytes;
+  }
 
-      resource
-        ?..overwrite(_vertices.asByteData())
-        ..overwrite(
-          _indices.asByteData(),
-          destinationOffsetInBytes: _vertices.lengthInBytes,
-        );
-    }
-    return resource;
+  @override
+  gpu.DeviceBuffer? createResource() {
+    final sizeInBytes = _vertices.lengthInBytes + _indices.lengthInBytes;
+    resourceSizeInByes = sizeInBytes;
+    return gpu.gpuContext.createDeviceBuffer(
+      gpu.StorageMode.hostVisible,
+      sizeInBytes,
+    )
+      ?..overwrite(_vertices.asByteData())
+      ..overwrite(
+        _indices.asByteData(),
+        destinationOffsetInBytes: _vertices.lengthInBytes,
+      );
   }
 
   void _calculateAabb(List<Vertex> vertices) {

packages/flame_3d/lib/src/resources/resource.dart

@@ -1,19 +1,21 @@
-import 'package:meta/meta.dart';
-
 // TODO(wolfenrain): in the long run it would be nice of we can make it
 // automatically refer to same type of objects to prevent memory leaks
 
 /// {@template resource}
 /// A Resource is the base class for any resource typed classes. The primary
 /// use case is to be a data container.
 /// {@endtemplate}
-class Resource<R> {
-  /// {@macro resource}
-  Resource(this._resource);
+abstract class Resource<R> {
+  R? _resource;
+  bool recreateResource = true;
+
+  R createResource();
 
-  /// The resource data.
-  R get resource => _resource;
-  @protected
-  set resource(R resource) => _resource = resource;
-  R _resource;
+  R get resource {
+    if (recreateResource) {
+      _resource = createResource();
+      recreateResource = false;
+    }
+    return _resource!;
+  }
 }

packages/flame_3d/lib/src/resources/shader/shader.dart

@@ -10,6 +10,8 @@ import 'package:flutter_gpu/gpu.dart' as gpu;
 ///
 /// {@endtemplate}
 class ShaderResource extends Resource<gpu.Shader> {
+  final gpu.Shader shader;
+
   /// {@macro shader_resource}
   factory ShaderResource.createFromAsset({
     required String asset,
@@ -22,17 +24,20 @@ class ShaderResource extends Resource<gpu.Shader> {
     if (shader == null) {
       throw StateError('Shader "$shaderName" not found in library "$asset"');
     }
-    return ShaderResource._(shader, slots: slots);
+    return ShaderResource._(shader: shader, slots: slots);
   }
 
-  ShaderResource._(
-    super.resource, {
+  ShaderResource._({
+    required this.shader,
     List<UniformSlot> slots = const [],
   }) {
     for (final slot in slots) {
-      slot.resource = resource.getUniformSlot(slot.name);
+      slot.uniformSlot = resource.getUniformSlot(slot.name);
     }
   }
+
+  @override
+  gpu.Shader createResource() => shader;
 }
 
 class Shader {

packages/flame_3d/lib/src/resources/shader/uniform_array.dart

@@ -19,27 +19,23 @@ class UniformArray extends UniformInstance<UniformArrayKey, ByteBuffer> {
   final List<Map<int, ({int hash, List<double> data})>> _storage = [];
 
   @override
-  ByteBuffer? get resource {
-    if (super.resource == null) {
-      final data = <double>[];
-      for (final element in _storage) {
-        var previousIndex = -1;
-        for (final entry in element.entries) {
-          if (previousIndex + 1 != entry.key) {
-            final field = slot.fields.indexed
-                .firstWhere((e) => e.$1 == previousIndex + 1);
-            throw StateError(
-              'Uniform ${slot.name}.${field.$2} was not set',
-            );
-          }
-          previousIndex = entry.key;
-          data.addAll(entry.value.data);
+  ByteBuffer createResource() {
+    final data = <double>[];
+    for (final element in _storage) {
+      var previousIndex = -1;
+      for (final entry in element.entries) {
+        if (previousIndex + 1 != entry.key) {
+          final field =
+              slot.fields.indexed.firstWhere((e) => e.$1 == previousIndex + 1);
+          throw StateError(
+            'Uniform ${slot.name}.${field.$2} was not set',
+          );
         }
+        previousIndex = entry.key;
+        data.addAll(entry.value.data);
       }
-      super.resource = Float32List.fromList(data).buffer;
     }
-
-    return super.resource;
+    return Float32List.fromList(data).buffer;
   }
 
   Map<int, ({int hash, List<double> data})> _get(int idx) {
@@ -67,7 +63,7 @@ class UniformArray extends UniformInstance<UniformArrayKey, ByteBuffer> {
     storage[index] = (data: data, hash: hash);
 
     // Clear the cache.
-    super.resource = null;
+    recreateResource = true;
   }
 
   @override

packages/flame_3d/lib/src/resources/shader/uniform_instance.dart

@@ -7,7 +7,7 @@ import 'package:flame_3d/resources.dart';
 /// {@endtemplate}
 abstract class UniformInstance<K, T> extends Resource<T?> {
   /// {@macro uniform_instance}
-  UniformInstance(this.slot) : super(null);
+  UniformInstance(this.slot);
 
   /// The slot this instance belongs too.
   final UniformSlot slot;

packages/flame_3d/lib/src/resources/shader/uniform_sampler.dart

@@ -5,6 +5,8 @@ import 'package:flame_3d/resources.dart';
 /// Instance of a uniform sampler. Represented by a [Texture].
 /// {@endtemplate}
 class UniformSampler extends UniformInstance<void, Texture> {
+  Texture? texture;
+
   /// {@macro uniform_sampler}
   UniformSampler(super.slot);
 
@@ -15,9 +17,13 @@ class UniformSampler extends UniformInstance<void, Texture> {
 
   @override
   void set(void key, Texture value) {
-    resource = value;
+    texture = value;
+    recreateResource = true;
   }
 
+  @override
+  Texture createResource() => texture!;
+
   @override
   void makeKey(int? idx, String? field) {}
 }

packages/flame_3d/lib/src/resources/shader/uniform_slot.dart

@@ -10,8 +10,7 @@ import 'package:flutter_gpu/gpu.dart' as gpu;
 /// {@endtemplate}
 class UniformSlot extends Resource<gpu.UniformSlot?> {
   UniformSlot._(this.name, this.fields, this._instanceCreator)
-      : _fieldIndices = {for (var (index, key) in fields.indexed) key: index},
-        super(null);
+      : _fieldIndices = {for (var (index, key) in fields.indexed) key: index};
 
   /// {@macro uniform_slot}
   ///
@@ -51,4 +50,14 @@ class UniformSlot extends Resource<gpu.UniformSlot?> {
   int indexOf(String field) => _fieldIndices[field]!;
 
   UniformInstance create() => _instanceCreator.call(this);
+
+  gpu.UniformSlot? _uniformSlot;
+
+  set uniformSlot(gpu.UniformSlot value) {
+    _uniformSlot = value;
+    recreateResource = true;
+  }
+
+  @override
+  gpu.UniformSlot? createResource() => _uniformSlot;
 }

packages/flame_3d/lib/src/resources/shader/uniform_value.dart

@@ -18,26 +18,21 @@ class UniformValue extends UniformInstance<String, ByteBuffer> {
   final Map<int, ({int hash, Float32List data})> _storage = HashMap();
 
   @override
-  ByteBuffer? get resource {
-    if (super.resource == null) {
-      var previousIndex = -1;
-
-      final entries = _storage.entries.toList()
-        ..sort(Comparing.on((c) => c.key));
-      final data = entries.fold<List<double>>([], (p, e) {
-        if (previousIndex + 1 != e.key) {
-          final field =
-              slot.fields.indexed.firstWhere((e) => e.$1 == previousIndex + 1);
-          throw StateError('Uniform ${slot.name}.${field.$2} was not set');
-        }
-        previousIndex = e.key;
-        return p..addAll(e.value.data);
-      });
-
-      super.resource = Float32List.fromList(data).buffer;
-    }
-
-    return super.resource;
+  ByteBuffer createResource() {
+    var previousIndex = -1;
+
+    final entries = _storage.entries.toList()..sort(Comparing.on((c) => c.key));
+    final data = entries.fold<List<double>>([], (p, e) {
+      if (previousIndex + 1 != e.key) {
+        final field =
+            slot.fields.indexed.firstWhere((e) => e.$1 == previousIndex + 1);
+        throw StateError('Uniform ${slot.name}.${field.$2} was not set');
+      }
+      previousIndex = e.key;
+      return p..addAll(e.value.data);
+    });
+
+    return Float32List.fromList(data).buffer;
   }
 
   Float32List? operator [](String key) => _storage[slot.indexOf(key)]?.data;
@@ -55,7 +50,7 @@ class UniformValue extends UniformInstance<String, ByteBuffer> {
     _storage[index] = (data: data, hash: hash);
 
     // Clear the cache.
-    super.resource = null;
+    recreateResource = true;
   }
 
   @override