Distance fog: the source

since 0.5.1 Light and environment
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: sky (line 14), pillars (line 51), fog (line 63).
1/// Distance fog: things farther from the eye fade toward one colour.
2///
3/// Quoted by `distance_fog.md` and shown whole in the Source tab.
4library;

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

10final class DistanceFogDemo extends ShowcaseDemo {
double density = 0.03;
bool matchSky = true;

static const SkySettings _sky = SkySettings(enabled: true);

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 9.0
    ..pitch = 0.08
    ..yaw = 0.0;
  context.orbit.target.setValues(0.0, 1.2, -10.0);
}

@override
Scene build(DemoContext context) {
  final Material stone = Material(
    name: 'stone',
    baseColor: Vector4(0.62, 0.58, 0.52, 1.0),
    roughness: 0.9,
  );
  final DeviceMesh pillar = DeviceMesh.upload(
    context.device,
    CuboidShape(size: Vector3(1.2, 3.0, 1.2)).build(),
  );
  final Scene scene = Scene()
    ..add(
      MeshNode(
        DeviceMesh.upload(
          context.device,
          const PlaneShape(width: 120, depth: 120).build(),
        ),
        stone.copy()..doubleSided = true,
        name: 'floor',
      ),
    )
    ..add(
      LightNode(name: 'sun', intensity: 3.0)
        ..setLocalForward(Vector3(-0.4, -0.8, -0.5)),
    );
  for (var i = 0; i < 12; i++) {
    scene.add(
      MeshNode(pillar, stone, name: 'pillar $i')
        ..setPosition(i.isEven ? -3.0 : 3.0, 1.5, -i * 4.5),
    );
  }
  return scene;
}

@override
RenderSettings settings(DemoContext context) => RenderSettings(
  sky: _sky,
  fog: FogSettings(
    // Read off the sky at the horizon, so the far end melts into it.
    color: matchSky
        ? _sky.sample(Vector3(0.0, 0.0, -1.0))
        : Vector3(0.6, 0.2, 0.2),
    density: density,
  ),
);

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  SliderControl(
    'Density',
    min: 0,
    max: 0.2,
    value: () => density,
    onChanged: (double v) => density = v,
    format: (double v) => v.toStringAsFixed(3),
  ),
  ToggleControl(
    'Fog takes the sky colour',
    value: () => matchSky,
    onChanged: (bool v) => matchSky = v,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  if (frame.drawCalls < scene.meshes.length) {
    throw StateError('some of the pillars were not drawn');
  }
}
95}