Baked visibility: the source

since 0.7.0 Simulation, audio and XR
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: level (line 38), bake (line 49), cull (line 66), live (line 83).
1/// Which parts of a level can be seen from where, decided before the game
2/// runs, and applied every frame by hiding the batches a camera cannot see.
3///
4/// Quoted by `baked_visibility.md` and shown whole in the Source tab.
5library;

7import 'dart:math' as math;

9import 'package:flutter3d/flutter3d.dart' hide Material;
10import 'package:flutter3d/flutter3d.dart' as f3d show Material;
11import 'package:flutter3d_app/flutter3d_app.dart';
12import 'package:flutter3d_showcase/src/demo/demo.dart';
13import 'package:flutter3d_showcase/src/demo/scene_kit.dart';
14import 'package:flutter3d_sim/flutter3d_sim.dart';
15import 'package:vector_math/vector_math.dart';

17final class BakedVisibilityDemo extends ShowcaseDemo {
late final String _report;

double eyeX = 0.0;
bool walking = true;

late final VisibilityCuller _live;
late final MeshNode _eye;
double _clock = 0.0;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 15.0
    ..pitch = 0.85
    ..yaw = 0.0;
  context.orbit.target.setValues(5.0, 0.0, 2.0);
}

@override
Scene build(DemoContext context) {
  // A floor the whole way along, and one solid wall crossing it a third of
  // the way down: nothing on the near side of the wall can be seen from
  // the far side.
  final level = Level(
    name: 'corridor',
    brushes: <Brush>[
      Brush(centre: Vector3(5, -2, 2), size: Vector3(14, 4, 4)),
      Brush(centre: Vector3(5, 1, 2), size: Vector3(1.0, 8, 4)),
    ],
  );

  final visibility = LevelVisibility.bake(level, cellSize: 1.0);

  final material = f3d.Material(
    name: 'room',
    baseColor: Vector4(0.6, 0.6, 0.8, 1.0),
  );
  final nearMarker = MeshNode(
    DeviceMesh.upload(context.device, CuboidShape().build()),
    material,
    name: 'near',
  )..setPositionFrom(Vector3(0, 0.5, 2));
  final farMarker = MeshNode(
    DeviceMesh.upload(context.device, CuboidShape().build()),
    material,
    name: 'far',
  )..setPositionFrom(Vector3(10, 0.5, 2));

  final culler = VisibilityCuller(visibility, <VisibilityBatch>[
    (
      node: nearMarker,
      bounds: Aabb3.minMax(Vector3(-1, 0, 1), Vector3(1, 2, 3)),
    ),
    (
      node: farMarker,
      bounds: Aabb3.minMax(Vector3(9, 0, 1), Vector3(11, 2, 3)),
    ),
  ]);
  final hiddenFromNearSide = culler.apply(Vector3(0, 0.2, 2));

  _report =
      'standing on the near side, $hiddenFromNearSide of 2 batches are '
      'hidden; near marker visible: ${nearMarker.visible}, far marker '
      'visible: ${farMarker.visible}';

  // The same culler, over four markers, asked again from wherever the eye
  // is each frame: a marker is on when the eye's own cell can see it.
  const List<double> stands = <double>[0.0, 1.5, 8.5, 10.0];
  final List<MeshNode> markers = <MeshNode>[
    for (final double x in stands)
      blockNode(
        context,
        'marker $x',
        Vector3(1.4, 1.4, 1.4),
        Vector4(0.85, 0.6, 0.35, 1.0),
        at: Vector3(x, 0.7, 2.0),
      ),
  ];
  _live = VisibilityCuller(visibility, <VisibilityBatch>[
    for (final MeshNode marker in markers)
      (
        node: marker,
        bounds: Aabb3.minMax(
          marker.readPosition() - Vector3.all(0.7),
          marker.readPosition() + Vector3.all(0.7),
        ),
      ),
  ]);
  _eye = ballNode(
    context,
    'eye',
    0.35,
    Vector4(0.45, 0.65, 0.95, 1.0),
    at: Vector3(0.0, 0.35, 2.0),
  );
  return sceneOf(<SceneNode>[
    blockNode(
      context,
      'floor',
      Vector3(14.0, 0.1, 4.0),
      Vector4(0.34, 0.38, 0.36, 1.0),
      at: Vector3(5.0, -0.05, 2.0),
    ),
    blockNode(
      context,
      'wall',
      Vector3(1.0, 3.0, 4.0),
      Vector4(0.55, 0.5, 0.5, 1.0),
      at: Vector3(5.0, 1.5, 2.0),
    ),
    _eye,
    ...markers,
  ]);
}

@override
void update(DemoContext context, double dt) {
  _clock += dt;
  if (walking) eyeX = 5.0 + 5.8 * math.sin(_clock * 0.4);
  _eye.setPosition(eyeX, 0.35, 2.0);
  _live.apply(Vector3(eyeX, 0.2, 2.0));
}

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  SliderControl(
    'Eye at',
    min: -1.0,
    max: 10.9,
    value: () => eyeX,
    onChanged: (double v) {
      walking = false;
      eyeX = v;
    },
    format: (double v) => '${v.toStringAsFixed(1)} m',
  ),
  ToggleControl(
    'Walk about',
    value: () => walking,
    onChanged: (bool v) => walking = v,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  if (frame.drawCalls < 1) {
    throw StateError('a marker was not drawn');
  }
  if (!_report.contains('near marker visible: true')) {
    throw StateError('the side the eye stands on should stay visible');
  }
  if (!_report.contains('far marker visible: false')) {
    throw StateError(
      'the far side of a solid wall with no doorway should be hidden',
    );
  }
}
175}