Fixing the "Cannot read properties of undefined (reading 'mask')" Error in R3F

Looking at your code, I can identify a few issues that might be causing the error when calling composer.render():

Main Issues

1. Camera Reference Problem: You're passing a React ref (firstCameraRef) directly to the RenderPass constructor instead of the actual camera object.

2. Render Target Configuration: You're setting up the composer but then manually changing render targets before calling composer.render().

3. Composer Size Management: The composer needs to know about size changes.

Solution

Here's how to fix these issues:

JAVASCRIPTCopied
// setup composer & effects
const [composer, savePass] = useMemo(() => {
  const composer = new EffectComposer(gl, renderTarget0);
  
  // Wait for the camera ref to be available
  // Don't pass the ref directly, but the current property
  const renderPass = new RenderPass(scene, camera);
  
  // Don't create this pass until firstCameraRef.current exists
  // const targetRenderPass = new RenderPass(scene, firstCameraRef.current);
  
  const savePass = new SavePass(renderTarget0);
  
  const BLOOM = new BloomEffect({
    luminanceThreshold: 0.3,
    luminanceSmoothing: 0.1,
  });
  
  const effectPass = new EffectPass(camera, BLOOM);
  
  composer.addPass(renderPass);
  // composer.addPass(targetRenderPass); // Add this only when camera ref is ready
  composer.addPass(effectPass);
  composer.addPass(savePass);
  
  return [composer, savePass];
}, [camera, gl, scene, renderTarget0]);

// Add this effect to handle resize and update the composer
useEffect(() => {
  composer.setSize(
    viewport.width * (isTouchDevice() ? touchDeviceDPR : noneTouchDeviceDPR),
    viewport.height * (isTouchDevice() ? touchDeviceDPR : noneTouchDeviceDPR)
  );
}, [composer, viewport, isTouchDevice, touchDeviceDPR, noneTouchDeviceDPR]);

// Add this effect to update the render pass when the camera ref is ready
useEffect(() => {
  if (firstCameraRef.current && composer) {
    const targetRenderPass = new RenderPass(scene, firstCameraRef.current);
    composer.insertPass(targetRenderPass, 0); // Insert at the beginning
  }
}, [firstCameraRef.current, composer, scene]);

// Modify your useFrame function
useFrame(({ gl, scene, camera }, delta) => {
  gl.autoClear = true;

  if (buddyRef.current != undefined) {
    buddyRef.current.visible = false;
  }
  
  if (renderScene0.current.render) {
    // Don't manually set render target before composer.render()
    // The composer will handle its own render targets
    
    // First render the scene to renderTarget0
    gl.setRenderTarget(renderTarget0);
    gl.render(scene, firstCameraRef.current);
    
    // Then let the composer do its work with effects
    // Make sure to set the render target back to null before composer.render()
    gl.setRenderTarget(null);
    composer.render(delta);
  }

  if (renderScene1.current.render) {
    // ... hide & show what i need to see
    gl.setRenderTarget(renderTarget1);
    gl.render(scene, secondCameraRef.current);
  }

  finalDisplayRef.current.visible = true;
  gl.setRenderTarget(null);
  gl.autoClear = false;
});

Additional Recommendations

1. Separate Rendering Concerns: Consider using separate composers for different render targets.

2. Check for Undefined References: Always ensure refs are defined before using them.

3. Use PostProcessing Properly: The postprocessing library (which provides EffectComposer and effects) expects to control its own render targets. Manually setting render targets before calling composer.render() can cause conflicts.

4. Consider Using Built-in R3F Effects: R3F provides components like <EffectComposer> that handle a lot of the setup for you.

This should help resolve the "Cannot read properties of undefined (reading 'mask')" error you're encountering.