I just recently switched from Babylonjs to Threejs. I love the performance and how light it is, but now I’m facing a problem.
I know that Threejs uses right-handed coordinate system, and I have to switch it to left-handed system to match Babylonjs play replays that I had before and scenarios that players created it will cause me a lot of headache to change all the coords.
So now I decided to fix this and I did fix it by flipping the z axis of the camera.
camera.scale.z = -1;
All worked but 1 issue only, the shadows are gone. I tried everything and I cannot seem to find a solution. I switched the scale of the camera back and I can see the shadow.
Anyone can help me here?
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That’s crazy that that even worked! Do your models not render insideout?
Maybe you have to invert shadowSide or something too…
https://threejs.org/docs/#api/en/materials/Material.shadowSide
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Woow! Thank you that worked as well!
Yes, I had the issue of render inside-out and finally found a solution: I was also able to fix it few moments ago by flipping both the camera and scene.
scene.scale.z = -1;
camera.scale.z = -1;
Will make the whole system left-handed fully without any issues so far.
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Very cool. I’m gonna have to remember this. 
good work!
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Just to clarify… when you swapped both scene and camera scale, did you still have to flip shadowSide?
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No. Also I removed the side: THREE.Double as well.
It worked perfect without any issues. I don’t know why this is not known yet because I see a lot of people asking how to flip the coords to left-handed.
But I’m not sure if this will cause any issues for any other people, but for me so far everything is rendering fine.
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That’s great to know. Hopefully I’ll remember it when someone asks… and/or it will show up in search. Churrs!
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