[Impeller] Sampling textures seem to have a black background sometimes #115031
Description
When the following application is run on Skia, we get the following expected output:
When running this on impeller, this shows with a black rectangle:
If I comment out the Text widgets in the Column, this renders correctly:
Adding other colors to the resulting output works correctly in all cases, so the problem seems to be with the texture.
main.dart
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter_shaders/flutter_shaders.dart';
void main() {
runApp(const MyApp());
}
final transform = Matrix4.identity().storage;
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: RepaintBoundary(
child: ShaderBuilder(
(BuildContext context, FragmentShader shader, Widget? child) {
return AnimatedSampler(
(ui.Image image, Size size, Offset offset, ui.Canvas canvas) {
canvas.translate(offset.dx, offset.dy);
var sampler = ImageShader(image, TileMode.clamp, TileMode.clamp, transform);
shader.setFloat(0, size.width);
shader.setFloat(1, size.height);
shader.setSampler(0, sampler);
canvas.translate(offset.dx, offset.dy);
canvas.drawRect(Offset.zero & size, Paint()..shader = shader);
},
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headlineMedium,
),
],
),
);
},
assetKey: 'shaders/sampler.frag',
),
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
),
);
}
}shaders/sampler.frag
precision highp float;
#include <flutter/runtime_effect.glsl>
layout(location = 0) uniform vec2 size;
layout(location = 1) uniform sampler2D uTexture;
out vec4 fragColor;
void main() {
vec2 uv = FlutterFragCoord() / size;
fragColor = texture(uTexture, uv);
}pubspec.yaml
name: foo_bar_shaders
description: A new Flutter project.
environment:
sdk: '>=2.19.0-374.0.dev <3.0.0'
dependencies:
flutter:
sdk: flutter
flutter_shaders: ^0.0.1
cupertino_icons: ^1.0.2
dev_dependencies:
flutter_test:
sdk: flutter
flutter_lints: ^2.0.0
flutter:
shaders:
- shaders/blur.frag
- shaders/sampler.frag