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An IBL doesn't give me shadows like a sun does, but a sun is very harsh. So, any suggestions?

That all depend on the map used for the IBL. If you have an HDRI with the light source included it should produce a shadow. Anyway, you can add a mesh light and scale it to create the level of harshness/softness thsat you want. Just position the light in sync with the light source in the IBL map and it will work well.

Cheers.

Paolo

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