What differs between them: the source

since 0.2.0 Backends
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: rows (line 42), stable (line 87).
1/// A live table of what the device open right now can do, read straight off
2/// `GraphicsDevice`, not off a name.
3///
4/// Quoted by `backend_matrix.md` and shown whole in the Source tab.
5library;

7import 'package:flutter/widgets.dart';
8import 'package:flutter3d/flutter3d.dart';
9import 'package:flutter3d_showcase/src/demo/capability_report.dart';
10import 'package:flutter3d_showcase/src/demo/demo.dart';
11import 'package:vector_math/vector_math.dart';

13final class BackendMatrixDemo extends ShowcaseDemo {
late final GraphicsDevice _device;
late final CapabilityReport _atBuild;

@override
Scene build(DemoContext context) {
  _device = context.device;
  _atBuild = context.caps;
  final Material stone = Material(
    name: 'stone',
    baseColor: Vector4(0.5, 0.5, 0.55, 1.0),
    roughness: 0.6,
  );
  final MeshNode ball = MeshNode(
    DeviceMesh.upload(
      context.device,
      SphereShape(segments: 24, rings: 12).build(),
    ),
    stone,
    name: 'ball',
  );
  return Scene()
    ..add(ball)
    ..add(
      LightNode(name: 'sun', intensity: 3.0)
        ..setLocalForward(Vector3(-0.4, -1.0, -0.3)),
    );
}

List<(String, String)> _rows(GraphicsDevice device) => <(String, String)>[
  ('wireframe', '${device.supportsWireframe}'),
  ('cube textures', '${device.supportsCubeTextures}'),
  ('mip maps', '${device.supportsMipmaps}'),
  ('render into a mip level', '${device.supportsRenderToMip}'),
  ('a stencil buffer', '${device.supportsStencil}'),
  ('a blend constant', '${device.supportsBlendColor}'),
  ('offscreen MSAA', '${device.supportsOffscreenMsaa}'),
  ('max anisotropy', '${device.maxAnisotropy}'),
  ('max colour attachments', '${device.maxColorAttachments}'),
  ('preferred sample count', '${device.preferredSampleCount}'),
];

@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),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            const Text(
              'What the device open right now answers to every capability '
              'question the engine asks. No name is read anywhere on this '
              'page; the table below is built entirely from the device.',
            ),
            const SizedBox(height: 16),
            for (final (String, String) row in _rows(context.device))
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 2),
                child: Text('${row.$1}: ${row.$2}'),
              ),
          ],
        ),
      ),
    );

@override
void verify(Scene scene, FrameResult frame) {
  if (frame.drawCalls < 1) {
    throw StateError('the ball was not drawn');
  }
  // The capability report this page showed at build time has to still
  // agree with a fresh reading of the same device after a frame has run.
  // A backend's answers are a property of the device, not something a
  // frame could have changed.
  final CapabilityReport now = CapabilityReport.of(_device);
  if (!now.met.containsAll(_atBuild.met) ||
      !_atBuild.met.containsAll(now.met)) {
    throw StateError(
      'the device answered a capability differently after a frame',
    );
  }
}
99}