Question regaurding lightmap atlas

Unity Engine
1

I have a question. Does the lightmapping know to put objects that utilize the same reflection probe and same material into the same lightmap for draw call minimizing?

2

any of you guys over at unity have an answer to this?

3

bump

4

relfection probes and lightmaps are seperate systems. Currently we do not do this optimization.

It is a good idea though.

5

Thanks for the reply. Any idea how i can choose what goes on what lightmap?

6

is there a process for that?

7

Grouping lightmap UV atlas islands by reflection probe would be good but a more generalised solution based on world position would be really useful too.

If the lightmapped objects within my current view frustum were all using the same lightmap then batching would be more efficient.

It would be trade off between lightmap UV packing efficiency (fewer lightmaps) and batching efficiency (potentially more lightmaps but fewer draw calls).

8

Is there a way to manually attempt this? grouping objects to a lightmap atlas per location?

9

In Unity 4 you could probably implement a hacky workaround by atlasing the scene in chunks, using Lock Atlas, then manually specifying the lightmap index used for every object in each chunk. Not pretty though.

Unity 5 doesn’t have the Lock Atlas option.

10

You can create a collection of Lightmap Parameters with different Baked Tag and use those to group the instances. It will not work exactly as the Lock Atlas of 4.x but it will guarantee that instances with different Baked Tag doesn’t end up in the same atlas.

1 Like
11

Ah interesting! So is that tag a kind of ‘hint’ for which lightmap to atlas on to? Presumably if there’s no room left on a particular lightmap it will create a new one? Or does it start to scale down the UV islands until they fit on to the specified one?

12

Heres a question… if 2 reflection probes fade into each other… what happens to the geometry in probe A , probe B, and points of blending geometry…

The question is in regaurds to draw calls. Would they all still be batched together with the same material… or divided up between whats in probe A and whats in probe B… or… divided up for probe A, probe B, and blend areas?