invisible emissive material

[romain.janil]

HI, I know this sounds odd, but is it possible to set a material to be invisible (ie surface is not displayed), not occluding etc)  yet its emission affects ssgi only ? maybe with a graph based mat, with standar mesh_base it doesn't seem doable ?

[silent]

Hi Romain,

That's not possible since all the screen-space effects are working with pixels that currently available in buffers (or on screen). You can bake emission from some source and disable it later.

Could you please tell us want do you want to achieve in terms of real world effects?

Thanks!

[romain.janil]

HI Silent, yep I've guessed that,  it was just a random out loud thought about ssgi, maybe filling an unseen buffer and use it after .

Of course I use lightvoxelprobes a lot to bake different lighting conditions and enable/disable them at real-time. I was trying to get real-dynamic (real-time) gi without using voxelprobes.

 So the long story short  is: I was indeed setting up some artificial lighting emission conditions (at city-landscape scale), and was tweaking around with the size of my emissive polygons (with ballon effect), in order to get right balance/efficiency between voxel sizes/power and area of the light polys, it's often(always) needed to make actual lighting polys larger than the real visible part: ie for  lampposts,  big 2-5 meter luminous spheres lead to far better results with large voxel size (~5m) than using directly the emission part of the lamppost which is really small and must of the time not caught by the baking process. In fact this is the same with ssgi, luminous parts of a lighting fixture are too small/most of the time occluded to participate to the ssgi , so I thought since big luminous ballons give me the lighting i'm after (think of airstar ballons for cine set lighting which are used a lot then erased in post), it's too bad I cant use them to light the scene/world and make them just invisible, and so use ssgi rand ssrtgi directly :)

Thanks !