Capturing a frame: the source

since 0.7.0 Scene and geometry
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: probe (line 21), capture (line 41), scene (line 54), check (line 80).
1/// A frame recorded pass by pass, with the pixels each pass wrote.
2library;

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

8final class FrameCaptureDemo extends ShowcaseDemo {
late final FrameCapture _capture;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 5.0
    ..pitch = 0.2
    ..yaw = 0.4;
}

@override
Future<void> prepare(DemoContext context) async {
  final Scene probe = Scene()
    ..add(
      MeshNode(
        DeviceMesh.upload(
          context.device,
          CuboidShape(size: Vector3.all(1.2)).build(),
        ),
        Material(name: 'probe', baseColor: Vector4(0.85, 0.42, 0.18, 1.0)),
        name: 'probe cube',
      ),
    )
    ..add(
      LightNode(name: 'sun', intensity: 3.0)
        ..setLocalForward(Vector3(-0.4, -0.8, -0.3)),
    );
  final CameraNode probeCamera = CameraNode()
    ..setPosition(0.0, 0.0, 4.0)
    ..lookAt(Vector3.zero());
  probe.add(probeCamera);

  final Future<FrameCapture> pending = context.renderer.captureNextFrame();
  context.renderer.render(
    width: 96,
    height: 96,
    scene: probe,
    views: <RenderView>[RenderView(camera: probeCamera)],
    settings: const RenderSettings(),
  );
  _capture = await pending;
}

@override
Scene build(DemoContext context) {
  final Scene scene = Scene()
    ..ambientColor = Vector3(0.42, 0.48, 0.64)
    ..ambientIntensity = 0.16
    ..add(
      MeshNode(
        DeviceMesh.upload(
          context.device,
          const TorusShape(radius: 1.0, tubeRadius: 0.4).build(),
        ),
        Material(
          name: 'torus',
          baseColor: Vector4(0.28, 0.62, 0.9, 1.0),
          roughness: 0.4,
        ),
        name: 'torus',
      ),
    )
    ..add(
      LightNode(name: 'sun', intensity: 3.2)
        ..setLocalForward(Vector3(-0.42, -0.8, -0.34)),
    );
  return scene;
}

@override
void verify(Scene scene, FrameResult frame) {
  final CapturedPass? scenePass = _capture.passNamed('scene');
  final CapturedImage? colour = scenePass?.imageOf('hdr_colour');
  if (scenePass == null ||
      !scenePass.active ||
      colour == null ||
      colour.isBlack ||
      frame.drawCalls < 1) {
    throw StateError('the captured frame did not record a lit scene pass');
  }
}
90}