Mesh editing overlays: the source

since 0.7.0 Scene and geometry
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: contributor (line 28), surface (line 35), camera (line 59), batches (line 77), controls (line 136), check (line 155).
1/// A modeller-style overlay drawn against the scene depth buffer.
2library;

4import 'dart:math' as math;

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

10final class MeshOverlayDemo extends ShowcaseDemo {
static const double _viewportHeight = 720;

late final MeshOverlay _overlay;
bool _vertices = true;
bool _face = true;
bool _through = true;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 6.2
    ..pitch = 0.28
    ..yaw = 0.62;
}

@override
Scene build(DemoContext context) {
  _overlay = context.renderer.addContributor(
    MeshOverlay(
      vertexShader: context.renderer.debugLineVertexShader,
      fragmentShader: context.renderer.debugLineFragmentShader,
    ),
  );

  final MeshNode cube = MeshNode(
    DeviceMesh.upload(
      context.device,
      CuboidShape(size: Vector3.all(2.0)).build(),
    ),
    Material(
      name: 'editable surface',
      baseColor: Vector4(0.16, 0.32, 0.52, 1.0),
      roughness: 0.58,
    ),
    name: 'editable cube',
  );
  final Scene scene = Scene()
    ..ambientColor = Vector3(0.45, 0.52, 0.68)
    ..ambientIntensity = 0.16
    ..add(cube)
    ..add(
      LightNode(name: 'key', intensity: 3.6)
        ..setLocalForward(Vector3(-0.45, -0.8, -0.35)),
    );
  _rebuild(context);
  return scene;
}

void _rebuild(DemoContext context) {
  final Matrix4 cameraWorld = context.camera.worldMatrix;
  final values = cameraWorld.storage;
  final Vector3 right = Vector3(values[0], values[1], values[2]);
  final Vector3 up = Vector3(values[4], values[5], values[6]);
  final double fov =
      context.camera.projection.verticalFieldOfView ?? math.pi / 4;
  _overlay
    ..clear()
    ..lookFrom(
      eye: context.camera.readWorldPosition(),
      right: right,
      up: up,
      pixel: 2.0 * math.tan(fov * 0.5) / _viewportHeight,
    );
  _writeGeometry();
}

void _writeGeometry() {
  final List<Vector3> corners = <Vector3>[
    for (final double z in <double>[-1, 1])
      for (final double y in <double>[-1, 1])
        for (final double x in <double>[-1, 1]) Vector3(x, y, z),
  ];
  final Vector4 edgeColour = Vector4(0.2, 0.82, 1.0, 1.0);
  for (final (int a, int b) in <(int, int)>[
    (0, 1),
    (0, 2),
    (1, 3),
    (2, 3),
    (4, 5),
    (4, 6),
    (5, 7),
    (6, 7),
    (0, 4),
    (1, 5),
    (2, 6),
    (3, 7),
  ]) {
    _overlay.edge(corners[a], corners[b], edgeColour);
  }
  if (_vertices) {
    for (final Vector3 corner in corners) {
      _overlay.point(corner, Vector4(1.0, 0.72, 0.12, 1.0), size: 11);
    }
  }
  if (_face) {
    final Vector4 selected = Vector4(0.2, 1.0, 0.45, 1.0);
    _overlay
      ..wash(corners[4], corners[5], corners[7], selected)
      ..wash(corners[4], corners[7], corners[6], selected)
      ..ribbon(corners[4], corners[7], selected, width: 5);
  }
  if (_through) {
    _overlay.throughGeometry(() {
      _overlay
        ..edge(
          Vector3(-1.6, 0.0, 0.0),
          Vector3(1.6, 0.0, 0.0),
          Vector4(0.78, 0.42, 1.0, 1.0),
        )
        ..ribbon(
          Vector3(0.0, -1.6, 0.0),
          Vector3(0.0, 1.6, 0.0),
          Vector4(0.78, 0.42, 1.0, 1.0),
          width: 7,
        )
        ..point(Vector3(0.0, 1.6, 0.0), Vector4(0.78, 0.42, 1.0, 1.0));
    });
  }
}

@override
void update(DemoContext context, double dt) => _rebuild(context);

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  ToggleControl(
    'Vertex handles',
    value: () => _vertices,
    onChanged: (bool value) => _vertices = value,
  ),
  ToggleControl(
    'Selected face',
    value: () => _face,
    onChanged: (bool value) => _face = value,
  ),
  ToggleControl(
    'Through-mesh gizmo',
    value: () => _through,
    onChanged: (bool value) => _through = value,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  if (_overlay.lines.vertexCount != 24 ||
      _overlay.handles.vertexCount != 54 ||
      _overlay.fill.vertexCount != 6 ||
      _overlay.linesThrough.isEmpty ||
      _overlay.handlesThrough.isEmpty ||
      frame.drawCalls < 6) {
    throw StateError('the mesh overlay batches did not reach the frame');
  }
}
164}