Blender : Eevee renderer : transparency/refraction

• Blender 2.8 and newer have two render engines: Eevee and Cycles.
• They behave very differently and require different levels of computer horsepower.
• This note is about Eevee, the less demanding of the two engines.

To get transparency and optical refraction for a Blender object, follow this recipe:

• In the Properties editor (at the right of the default Layout configuration), select the tab with the little TV symbol (Context: Render).
• Select the Eevee render engine if it's not already selected.
• Locate and enable the "Screen Space Reflections" check-box, open its submenu and enable "Refraction."
• Select (i.e. click) an object you want to make transparent and have optical behaviors.
• In the Properties editor, select the lower of the two red globe tabs (Context: Material).
• If no material has been created for your object, click "New" to create a default material.
• Scroll through the properties of the material, set "Roughness" to 0 and "Transmission" to 1 — this enables optical transparency.
• Scroll down in the same context, open "Settings", locate "Screen Space Refraction" and enable it.

With these settings, the selected object will be completely transparent and will show approximate optical refraction with respect to objects behind it. (The Eevee render engine only approximates true optical refraction — for more accurate optical effects one must use the Cycles render engine. The main article explains this issue.)