Anisotropic texture filtering: the source

since 0.4.3 Shading and materials
Open the live demo · Read the guide · View on GitHub
Regions the guide quotes: texture (line 30), floor (line 42), settings (line 68).
1/// Anisotropic filtering: a checkerboard floor that stays sharp toward the
2/// horizon.
3///
4/// Quoted by `texture_filtering.md` and shown whole in the Source tab.
5library;

7import 'dart:typed_data';

9import 'package:flutter3d/flutter3d.dart';
10import 'package:flutter3d_showcase/src/demo/demo.dart';
11import 'package:vector_math/vector_math.dart';

13final class TextureFilteringDemo extends ShowcaseDemo {
int anisotropyChoice = 3;

static const List<int> _levels = <int>[1, 2, 4, 8, 16];
static const int _size = 256;

@override
void configureView(DemoContext context) {
  context.orbit
    ..distance = 3.0
    ..yaw = 0.0
    ..pitch = 0.07;
  context.orbit.target.setValues(0.0, 0.2, 0.0);
}

@override
Scene build(DemoContext context) {
  final ByteData pixels = const CheckerboardTexture(
    size: _size,
    cell: 16,
  ).encode();
  final TextureHandle checks = context.device.createTextureFromPixels(
    width: _size,
    height: _size,
    format: TextureFormat.r8g8b8a8UNormInt,
    pixels: pixels,
    mipLevels: MipChain.build(pixels, _size, _size),
  )!;

  final Material floor = Material(
    name: 'checks',
    albedo: checks,
    albedoSampler: SamplerOptions.trilinearRepeat,
    roughness: 0.9,
    doubleSided: true,
  );
  final MeshNode ground = MeshNode(
    DeviceMesh.upload(
      context.device,
      const PlaneShape(width: 60, depth: 60).build(),
    ),
    floor,
    name: 'floor',
  );

  return Scene()
    ..add(ground)
    ..add(
      LightNode(name: 'sun', intensity: 3.0)
        ..setLocalForward(Vector3(-0.3, -1.0, -0.4)),
    );
}

@override
RenderSettings settings(DemoContext context) => RenderSettings(
  anisotropy: _levels[anisotropyChoice],
);

@override
List<DemoControl> controls(DemoContext context) => <DemoControl>[
  ChoiceControl(
    'Anisotropy',
    options: <String>[for (final int level in _levels) '${level}x'],
    index: () => anisotropyChoice,
    onChanged: (int i) => anisotropyChoice = i,
  ),
];

@override
void verify(Scene scene, FrameResult frame) {
  final Material floor = scene.meshes.first.material;
  if (floor.albedoSampler?.mipFilter != MipFilter.linear) {
    throw StateError('the floor sampler does not blend mip levels');
  }
  if (_levels[anisotropyChoice] <= 1) {
    throw StateError('anisotropy is off, so nothing here is filtered');
  }
  if (frame.drawCalls < 1) throw StateError('the floor was not drawn');
}
92}