Several views in one frame: the source

since 0.7.0 Scene and geometry
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: layers (line 24), rect (line 57), split (line 65), controls (line 87), check (line 96).
1/// One `RenderView` cropped to a rectangle, and two combined in one frame.
2library;

4import 'package:flutter3d/flutter3d.dart';
5import 'package:flutter3d_showcase/src/demo/demo.dart';
6import 'package:vector_math/vector_math.dart';

8final class MultiViewDemo extends ShowcaseDemo {
bool showLeft = true;

late final Scene _scene;
FrameResult? _combined;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 6.0
    ..pitch = 0.15
    ..yaw = 0.0;
}

@override
Scene build(DemoContext context) {
  final MeshNode leftCube =
      MeshNode(
          DeviceMesh.upload(
            context.device,
            CuboidShape(size: Vector3.all(1.0)).build(),
          ),
          Material(name: 'left', baseColor: Vector4(0.2, 0.55, 0.95, 1.0)),
          name: 'left cube',
        )
        ..setPosition(-1.4, 0.0, 0.0)
        ..layerMask = 1;
  final MeshNode rightCube =
      MeshNode(
          DeviceMesh.upload(
            context.device,
            CuboidShape(size: Vector3.all(1.0)).build(),
          ),
          Material(name: 'right', baseColor: Vector4(0.95, 0.42, 0.2, 1.0)),
          name: 'right cube',
        )
        ..setPosition(1.4, 0.0, 0.0)
        ..layerMask = 2;

  _scene = Scene()
    ..ambientColor = Vector3(0.45, 0.5, 0.6)
    ..ambientIntensity = 0.16
    ..add(leftCube)
    ..add(rightCube)
    ..add(
      LightNode(name: 'key', intensity: 3.0)
        ..setLocalForward(Vector3(-0.4, -0.7, -0.5)),
    );

  context.view
    ..viewportFraction = const ViewportRect(0.0, 0.0, 0.5, 1.0)
    ..layerMask = showLeft ? 1 : 2;
  return _scene;
}

@override
void update(DemoContext context, double dt) {
  final RenderView left = RenderView(
    camera: context.camera,
    viewportFraction: const ViewportRect(0.0, 0.0, 0.5, 1.0),
    layerMask: 1,
  );
  final RenderView right = RenderView(
    camera: context.camera,
    viewportFraction: const ViewportRect(0.5, 0.0, 0.5, 1.0),
    layerMask: 2,
  );
  _combined = context.renderer.render(
    width: 320,
    height: 180,
    scene: _scene,
    views: <RenderView>[left, right],
    settings: const RenderSettings(),
  );
  context.view.layerMask = showLeft ? 1 : 2;
}

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  ToggleControl(
    'Show the left layer',
    value: () => showLeft,
    onChanged: (bool value) => showLeft = value,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  final FrameResult? combined = _combined;
  if (combined == null || combined.drawCalls <= frame.drawCalls) {
    throw StateError('two views in one frame did not draw more than one');
  }
}
101}