The software rasteriser: the source

since 0.2.0 Backends
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: read (line 39), verify (line 65).
1/// The software rasteriser: no driver, no shading language, no command
2/// buffer, and no GPU underneath any of it.
3///
4/// Quoted by `backend_cpu.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/demo.dart';
10import 'package:vector_math/vector_math.dart';

12final class BackendCpuDemo extends ShowcaseDemo {
late final GraphicsDevice _device;

@override
Scene build(DemoContext context) {
  _device = context.device;
  final Material stone = Material(
    name: 'stone',
    baseColor: Vector4(0.6, 0.6, 0.65, 1.0),
    roughness: 0.7,
  );
  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)),
    );
}

String _report(GraphicsDevice device) =>
    'preferred sample count: ${device.preferredSampleCount}\n'
    'offscreen MSAA: ${device.supportsOffscreenMsaa}\n'
    'wireframe: ${device.supportsWireframe}\n'
    'stencil: ${device.supportsStencil}\n'
    'mip maps: ${device.supportsMipmaps}';

@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: Text(
      'This build asked flutter3d_hardware\'s registry for a backend and '
      'got the software rasteriser: no driver, no shading language, no '
      'command buffer, so a backend agreeing with the hardware ones proves '
      'something.\n\n${_report(context.device)}',
    ),
  ),
);

void _checkNoMultisampling() {
  if (_device.preferredSampleCount != 1 || _device.supportsOffscreenMsaa) {
    throw StateError(
      'the software rasteriser answering anything but "no multisampling" '
      'would be a silent difference from the picture a hardware backend '
      'draws',
    );
  }
}

@override
void verify(Scene scene, FrameResult frame) {
  if (frame.drawCalls < 1) {
    throw StateError('the ball was not drawn');
  }
  _checkNoMultisampling();
}
82}