[rive_native] Setting RenderTexturePainter clear to false not working

[naychrist]

Hi @HayesGordon glad to see rive_native in the main package now!

Just moving this issue here from the previous tracker:

On web: setting RenderTexturePainter clear to false does nothing

On desktop: setting RenderTexturePainter clear to false prevents clearing but renders previous vectors with a jitter/vibration

Here is the example again that I have been testing with:

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:rive/rive.dart' as rive;


class RenderTexturePainterExample extends StatefulWidget {
  const RenderTexturePainterExample({super.key});

  @override
  State<RenderTexturePainterExample> createState() =>
      _RenderTexturePainterExampleState();
}

class _RenderTexturePainterExampleState
    extends State<RenderTexturePainterExample> {

  bool isRiveRender = true;

  final rive.RenderTexture _renderTexture =
  rive.RiveNative.instance.makeRenderTexture();


  GamePainter? _myRivePainter;

  @override
  void initState() {
    loadFile();
    super.initState();
  }

  rive.File? riveFile;

  Future<void> loadFile() async {
    final bytes = await rootBundle.load("assets/zombie.riv");
    riveFile = await rive.File.decode(bytes.buffer.asUint8List(),
        riveFactory: isRiveRender ? rive.Factory.rive : rive.Factory.flutter);

    if (riveFile != null) {
      setState(() {
        _myRivePainter = GamePainter(riveFile!);
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    if (riveFile == null) return const SizedBox();
    return ColoredBox(
      color: const Color(0xFF507FBA),
      child: Center(
        child: _myRivePainter == null
            ? const SizedBox()
            : _renderTexture.widget(painter: _myRivePainter!),
      ),
    );
  }
}


final class GamePainter extends rive.RenderTexturePainter {

  final rive.File riveFile;

  final Set<rive.Artboard> allZombieArtboards = {};
  final Set<rive.StateMachine> allZombieStateMachines = {};



  GamePainter(this.riveFile) {

    int numZombies = 10;
    for (int i = 0; i < numZombies; i++) {
      var ab = riveFile.artboard("Zombie man")!;
      allZombieArtboards.add(ab);
      allZombieStateMachines.add(ab.stateMachine("Motion")!);
      allZombieStateMachines.last.number("numSkins")!.value = i%6;
    }

  }

  double y = 0;/// used to show trail

  @override
  bool paint(rive.RenderTexture texture, double devicePixelRatio, Size size, double elapsedSeconds) {

    final renderer = texture.renderer;

    /// draw zombies
    double spacing = size.width / allZombieArtboards.length;
    for (int i = 0; i < allZombieArtboards.length; i++) {
      var artboard = allZombieArtboards.elementAt(i);
      var statemachine = allZombieStateMachines.elementAt(i);
      statemachine.advanceAndApply(elapsedSeconds);
      renderer.save();
      renderer.translate(spacing * i - spacing/2, y);
      artboard.draw(renderer);
      renderer.restore();
    }

    ///draw test ellipse
    final rive.RenderPaint paintFill = texture.renderer.riveFactory.makePaint()
      ..style = rive.PaintingStyle.fill
      ..color = Colors.white;
    final rive.RenderPaint paintStroke = texture.renderer.riveFactory.makePaint()
      ..style = rive.PaintingStyle.stroke
      ..color = Colors.black;
    texture.renderer.drawCircle( Offset(y, y), 50, paintFill);
    texture.renderer.drawCircle( Offset(y, y), 50, paintStroke);

    y += 1;

    return true;
  }

  @override
  bool get clear => false;//does not work


  @override
  void dispose() {
    riveFile.dispose();
    for (var ab in allZombieArtboards) {
      ab.dispose();
    }
    for (var sm in allZombieStateMachines) {
      sm.dispose();
    }
    super.dispose();
  }

  @override
  Color get background => Colors.transparent;
}