Identical-draw batching: the source

since 0.7.0 Shading and materials
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: crates (line 26), settings (line 57), check (line 71).
1/// `RenderSettings.batchIdenticalDraws`: a run of nodes sharing a mesh and a
2/// material collapses into one instanced call.
3///
4/// Quoted by `draw_batching.md` and shown whole in the Source tab.
5library;

7import 'package:flutter3d/flutter3d.dart';
8import 'package:flutter3d_showcase/src/demo/demo.dart';
9import 'package:vector_math/vector_math.dart';

11final class DrawBatchingDemo extends ShowcaseDemo {
bool batch = true;

static const int _rows = 3;
static const int _columns = 4;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 9.0
    ..pitch = 0.35;
}

@override
Scene build(DemoContext context) {
  final DeviceMesh crateMesh = DeviceMesh.upload(
    context.device,
    CuboidShape(size: Vector3(0.8, 0.8, 0.8)).build(),
  );
  final Material crateMaterial = Material(
    name: 'crate',
    baseColor: Vector4(0.7, 0.55, 0.3, 1.0),
    roughness: 0.7,
  );
  final Scene scene = Scene();
  for (var row = 0; row < _rows; row++) {
    for (var column = 0; column < _columns; column++) {
      scene.add(
        MeshNode(crateMesh, crateMaterial, name: 'crate $row-$column')
          ..setPosition(
            (column - (_columns - 1) / 2) * 1.1,
            0.0,
            (row - (_rows - 1) / 2) * 1.1,
          ),
      );
    }
  }

  return scene..add(
    LightNode(name: 'sun', intensity: 3.0)
      ..setLocalForward(Vector3(-0.4, -0.8, -0.5)),
  );
}

@override
RenderSettings settings(DemoContext context) => RenderSettings(
  batchIdenticalDraws: batch,
);

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  ToggleControl(
    'Batch identical draws',
    value: () => batch,
    onChanged: (bool v) => batch = v,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  final int crates = _rows * _columns;
  if (scene.meshes.length != crates) {
    throw StateError('expected $crates crates, found ${scene.meshes.length}');
  }
  if (batch && frame.batchedDraws < RenderSettings.batchRunMinimum) {
    throw StateError(
      'batching was on but only ${frame.batchedDraws} draws were merged',
    );
  }
  if (!batch && frame.batchedDraws != 0) {
    throw StateError(
      'batching was off but ${frame.batchedDraws} draws merged',
    );
  }
}
86}