Hi there!
I created a small plane geometry (not in full screen) with as material a RenderTexture of a nested scene.
Into the RenderTexture I added a EffectComposer (Bloom effect) so that it only be applied to the RenderTexture. Unfortunately the EffectComposer seems to be creating a fullscreen triangle over the
scene instead of being contained within the texture of my plane geometry 
Is there a workaround for this ?
Thank you !
Hi!
Running into the exact same problem here…
Minimal sandbox forked from example here: drei/RenderTexture (forked) - CodeSandbox
without postprocessing:
with postprocessing:
Already had a look at autoRenderToScreen parameter which did not solve the problem as it is already set to false (link to the doc)
[edit: added actual link to the doc]
I solved the issue by passing the RenderTexture scene & camera to the EffectComposer tag.
I used the onUpdate function from the RenderTexture tag by looping over the __r3f.parent until I retrieve the scene and camera.Then I can apply them to the RenderTexture tag.
<EffectComposer disableNormalPass scene={nestedScene} camera={nestedCamera}>
<Bloom luminanceThreshold={0.2} luminanceSmoothing={0.5} radius={10} height={300} />
</EffectComposer>
This way, my Bloom effect is only applied to the nested scene 
thanks a lot! unfortunately it doesn’t seem to work here… I’ve made another sandbox to test it: drei/RenderTexture (forked) - CodeSandbox
@sebastien_lempens do you have some sample code you could upload for me to check what I’m doing wrong?
Sorry I didn’t manage to reproduce it on your code 
The difference in my project is i’m using 2 nested RenderTexture, maybe that’s why it looks to be working.
I will try to make a codepen project of it… In meantime I hope you will figure out a solution.
Finally I managed to use postprecessing effects into the cube
I had to use my own prostprocessing effects and play with currrentTargets !
