Reply To: What is the difference between “Alpha Blend” and “Alpha Hashed”?

[Ingmar Franz]

Thanky you @jlampel, this helps me deciding when to use what mode. Especially the difference in colored transparency is something I didn’t know. 

One question to your explanations: What does this “sorting” mean?

I’ve taken a look once again into the Blender 2.90 manual here but these explanations are very technical and rather for programmers🤪:

Blend Mode

After calculating the color of a surface, the blend mode defines how it is added to the color buffer. Depending on this, the final color will be different.

Note

Alpha Blending is considered a “Transparent” blend mode and has implications regarding screen space effects.

Opaque

The previous color will be overwritten by the surface color. The alpha component is ignored. This is the fastest option.

Alpha Clip

The previous color will be overwritten by the surface color, but only if the alpha value is above the clip threshold.

Alpha Hashed

The previous color will be overwritten by the surface color, but only if the alpha value is above a random clip threshold. This statistical approach is noisy but is able to approximate alpha blending without any sorting problem. Increasing the sample count in the render settings will reduce the resulting noise.

Alpha Blending

Use alpha blending to overlay the surface color on top of the previous color.

Sorting Problem

When writing to the color buffer using transparent blend modes, the order in which the color blending happens is important as it can change the final output color. As of now Eevee does not support per-fragment (pixel) sorting or per-triangle sorting. Only per-object sorting is available and is automatically done on all transparent surfaces based on object origin.

Note

This per-object sorting has already a cost and having thousands of these objects in a scene will greatly degrade performance.