flutter3d_impeller 0.4.0

The flutter_gpu backend for flutter3d: one implementation of flutter3d_hardware, and the only place in the stack that names a graphics API.

flutter3d_impeller

flutter3d_hardware over flutter_gpu: the backend a desktop or mobile build draws through.

final device = await GpuRenderBackend.create();
final renderer = Renderer.create(device: device);

Nothing else in the stack names flutter_gpu. Swapping this for another backend is a change to one line of application wiring — which is the property the split exists for, and the reason there are two more backends to prove it with.

The shader bundle

flutter_gpu wants shaders compiled ahead of time, so this package builds one:

./tool/build_shaders.sh

The bundle is gitignored and its format is tied to the SDK version, so a fresh checkout has none until that runs. A test asserts it was built — deliberately a failure rather than a skip, because "CI built only one bundle" is exactly the trap that test exists to catch.

Run it again after every shader edit. The sources live in flutter3d_shaders, and editing one changes nothing an application loads until this rebuilds. The failure that follows is the reason this paragraph exists: not a shader behaving oddly, but failed to bind texture, because the renderer binds a slot the new GLSL declares and the compiled binary has not got. The message names neither the shader nor the edit.

dart run tool/structure.dart compares the bundle against its sources and says which are newer, so the mistake is a red rule rather than an afternoon. It skips when there is no bundle, which is every checkout without impellerc.

The entry point is here rather than in flutter3d and has to be: the script calls impellerc, which is this backend's compiler and not the engine's business, and a scan holds the engine to naming no backend at all. An extension package outside this repository runs the same build against its own shaders:

dart run flutter3d_impeller:build_shaders

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Part of flutter3d, an independent implementation of a 3D engine for Flutter — not a fork or a binding of another engine, and not affiliated with the Flutter team. Three switchable rendering backends: Impeller via Flutter GPU, WebGL2, and a software rasteriser. glTF, OBJ and .f3d loading, six lighting models, shadows, bloom, skinning, animation, BVH culling and picking; a deterministic fixed-step game layer with collision, navigation, positional audio, and gamepad and touch input. Three example games — shooter, platformer, racing — each built on its genre package: flutter3d_game_shooter, flutter3d_game_platformer, flutter3d_game_racing. A new game starts from apps/flutter3d_template_app. Documentation: https://flutter3d.pleion.dev.