The field kept current: the source

since 0.8.0 Light and environment
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: room (line 36), field (line 81), live (line 97).
1/// The irradiance field kept current by the renderer: a few probes a frame
2/// look at the room again, so the bounce follows a wall that changes colour.
3///
4/// Quoted by `irradiance_updates.md` and shown whole in the Source tab.
5library;

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

11final class IrradianceUpdatesDemo extends ShowcaseDemo {
int wallColour = 0;
double probesPerFrame = 2;
double hysteresis = 0.9;

late final Material _paint;
late final IrradianceField _field;

static final List<Vector4> _colours = <Vector4>[
  Vector4(0.85, 0.08, 0.08, 1.0),
  Vector4(0.08, 0.7, 0.12, 1.0),
  Vector4(0.1, 0.2, 0.85, 1.0),
];

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 6.0
    ..pitch = 0.35
    ..yaw = 0.5;
  context.orbit.target.setValues(-0.5, 1.0, 0.0);
}

@override
Scene build(DemoContext context) {
  final Material floor = Material(
    name: 'floor',
    baseColor: Vector4(0.55, 0.55, 0.55, 1.0),
    roughness: 0.95,
    doubleSided: true,
  );
  _paint = Material(
    name: 'painted wall',
    baseColor: _colours[wallColour].clone(),
    roughness: 0.95,
    doubleSided: true,
  );
  final Scene scene = Scene()
    ..ambientIntensity = 1.0
    ..add(
      MeshNode(
        DeviceMesh.upload(
          context.device,
          const PlaneShape(width: 6, depth: 6).build(),
        ),
        floor,
        name: 'floor',
      ),
    )
    ..add(
      MeshNode(
          DeviceMesh.upload(
            context.device,
            const PlaneShape(width: 3, depth: 4).build(),
          ),
          _paint,
          name: 'wall',
        )
        ..setPosition(-2.0, 1.5, 0.0)
        ..setRotation(Quaternion.axisAngle(Vector3(0.0, 0.0, 1.0), -1.5708)),
    )
    ..add(
      LightNode(
        name: 'lamp',
        type: LightType.point,
        intensity: 30.0,
        range: 12.0,
      )..setPosition(-0.8, 2.5, 0.0),
    );

  _field =
      IrradianceField(
          origin: Vector3(-1.0, 0.5, -1.0),
          spacing: Vector3(1.0, 1.0, 1.0),
          countX: 2,
          countY: 2,
          countZ: 2,
        )
        ..gpuUpdates = probesPerFrame.round()
        ..fillGutters();
  scene.irradianceField = _field;
  return scene;
}

@override
void update(DemoContext context, double dt) {
  _paint.baseColor.setFrom(_colours[wallColour]);
  _field
    ..gpuUpdates = probesPerFrame.round()
    ..hysteresis = hysteresis;
}

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  ChoiceControl(
    'Wall colour',
    options: const <String>['Red', 'Green', 'Blue'],
    index: () => wallColour,
    onChanged: (int i) => wallColour = i,
  ),
  SliderControl(
    'Probes a frame',
    min: 1,
    max: 8,
    divisions: 7,
    value: () => probesPerFrame,
    onChanged: (double v) => probesPerFrame = v,
    format: (double v) => '${v.round()}',
  ),
  SliderControl(
    'Hysteresis',
    min: 0,
    max: 0.99,
    value: () => hysteresis,
    onChanged: (double v) => hysteresis = v,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  final PassSkip? skipped = frame.skipReasonOf('irradiance update');
  if (skipped != null) {
    throw StateError('the probe update was skipped: $skipped');
  }
  if (!frame.passes.any((FramePass p) => p.name == 'irradiance update')) {
    throw StateError('no probe was updated this frame');
  }
}
139}