The .f3d container: the source

since 0.1.0 Formats and I/O
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: write (line 30), read (line 36), report (line 55), check (line 80).
1/// `.f3d`: the engine's own container, built to load without parsing.
2///
3/// Quoted by `f3d.md` and shown whole in the Source tab.
4library;

6import 'package:flutter/widgets.dart';
7import 'package:flutter3d/flutter3d.dart';
8import 'package:flutter3d_showcase/src/demo/demo.dart';
9import 'package:vector_math/vector_math.dart';

11final class F3dDemo extends ShowcaseDemo {
late final F3dDocument _decoded;
late final int _fileBytes;
late final int _glbBytes;

final _document = PlainModelDocument(
  surfaces: <ModelSurface>[
    ModelSurface(
      mesh: SphereShape(segments: 32, rings: 16).build(),
      materialIndex: 0,
    ),
  ],
  materials: <SurfaceMaterial>[
    SurfaceMaterial(baseColor: Vector4(0.4, 0.7, 0.5, 1.0)),
  ],
);

@override
Scene build(DemoContext context) {
  // `F3dWriter.write` is the offline half, run once by
  // `dart run flutter3d_build:convert`. Nothing here is on a frame path.
  final bytes = F3dWriter(_document).write();
  _fileBytes = bytes.length;
  _glbBytes = GltfWriter(_document).writeGlb().length;

  // Parsing reads the header and the section directory; every array the
  // engine asks for afterwards, `surfaces` included, is a view over these
  // same bytes rather than a copy.
  _decoded = F3dDocument.parse(bytes);

  return Scene()
    ..add(
      MeshNode(
        DeviceMesh.upload(context.device, _decoded.surfaces.single.mesh),
        Material(baseColor: Vector4(0.4, 0.7, 0.5, 1.0)),
        name: 'ball',
      ),
    )
    ..add(
      LightNode(name: 'sun', intensity: 3.0)
        ..setLocalForward(Vector3(-0.4, -1.0, -0.3)),
    );
}

String _report() =>
    '.f3d bytes: $_fileBytes\n'
    '.glb bytes (for comparison): $_glbBytes\n'
    'surfaces: ${_decoded.surfaces.length}\n'
    'vertices: ${_decoded.vertexCount}\n'
    'triangles: ${_decoded.triangleCount}';

@override
Widget? customBody(BuildContext buildContext, DemoContext context) =>
    Container(
      color: const Color(0xFF14161A),
      padding: const EdgeInsets.all(24),
      alignment: Alignment.topLeft,
      child: DefaultTextStyle(
        style: const TextStyle(
          color: Color(0xFFE8E8EC),
          fontSize: 16,
          fontFamily: 'monospace',
        ),
        child: Text(_report()),
      ),
    );

@override
void verify(Scene scene, FrameResult frame) {
  final differences = compareModelDocuments(_document, _decoded);
  if (differences.isNotEmpty) {
    throw StateError(
      'the round trip through .f3d changed something: '
      '$differences',
    );
  }
  if (_decoded.surfaces.isEmpty) {
    throw StateError('the file decoded to no surfaces');
  }
  if (frame.drawCalls < 1) {
    throw StateError('the ball was not drawn');
  }
}
94}