Alpha Pass For Baking
Right now I have to work with foliage for UE4. And I need to bake custom ( different than SpeedTree do ) billboarsd for trees. And I always was sure that baking through alpha is something absolutely obvious. But I was wrong. I spant hours and hours on googling for solution. I tried almost everything what comes in to my mind - nothing work. It's something impossible.
Then I started to search in 3D Max - same shit. Render alpha - anything you want. Render To Texture ( bake ) through alpha - nope, never!!!
I even ask on Blender Stack Exchange. But still no answer ( and it seems that the only person who visited this page is me).
I even ask poople in office (~50) - is anyone know how to do this....
The only solution I found then - one guy in my office work with Houdini, he tried and it bake through alpha without any issues. So now I have to learn Houdini. Houdini is interesting and powerful software. Challenge accepted, but still .... I think Blender should be able to do such simply thing as bake through alpha.
PS Correct me if I wrong and Blender can do this (camera render is not considered). I have never wanted to be so wrong.
As always - thanks for reading. Also you can check my other suggestions .
10 Comments
I'm assuming this is still not a resolved issue as I've just run into it in the year of our Lord 2025.
I'm running into this particular issue trying to get the Brushstrokes Tools plugin from Blender to bake down into diffuse and normal maps. So using a 3rd party application won't even solve my issue.
Anyone her having a favorite goto program as long as this is not fixed?
speedtree
How this could work in terms of being fixed in code; Instead of JUST layering alpha by geometry, the layer's alpha must be blended with clamped additive pass, so that the black is ignored and the white in the alpha is correctly combined. Trouble is, I'm not sure if this can be done with shader setup. This would probably require a re-work of the current alpha baking solution.
My current advice; Try to layer all of your effects within the one shader, or combine passes in compositor. But that's not much of a workaround.
* @simon.p.heggie * ... combine passes in compositor? Really? How many passes it need to combine to just bake one tree to billboard texture?
I just ask to let me bake same picture as I see in viewport. Why viewport can show me material with alpha blend, but baker which work on same graphic engine cant bake alpha... It just stupid.
Lack of such simply thing cut out many potential users who work with foliage, low poly baked assets and etc.
* @IIIFGIII * Lol dude, I feel the same way about it as you do, let me clarify what I said:
I think It can be done, I think it should be in there, and the workarounds suck XD
As for HOW exactly, thinking about that might increase the odds that this get's made.
I'm also trying to relay my thought process in a way that you may be familiar with. I'm guessing you've worked with nodes/compositing, this is kind of like what happens behind the scenes in Blenders renders.
Like; I'm thinking that the way the baking engine layers the alpha is kind of like if you had the mix node value at '1', over the top of everything else, the black areas of the alpha would simply eclipse every other white alpha value.
But I think the way the bake engine should work is more like a mix node with an additive setting, with 'Clamp' on.
If you try this with some nodes in the compositor you'll see what I mean, a similar effect with combining alpha in the baking would probably be helpful.
We may need to have some kind of sample setting for z-depth buffer stuff.
So maybe this kind of discussion thread might give a programmer an idea on where to start.
-S
Really, I just wasted like 7 hours rendering single layers and in the end, I got so fed up that I just used a camera and rendered it straight forward. It's a million times faster than doing anything one by one, and all you have to do manually is switching the material color output from map to map and save the render in the apropriate format. Houdini is cool and all, but without paying you can't export 4k, and well, it's just a too trivial of a task to dive into this powerhouse. Procedual landscape creation ok, baking a efin texture, wtf.
Well you have two solution in blender as far I can tell. A) Use camera render and put the different map outputs into emissive B)Sort your meshes-to-be-projected into layers without any overlappings per layer, and then bake them layer by layer, save them as individual files and merge them in gimp or photoshop. It's ridiculous. Thanks for the hint to houdini.
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* @Antonio Puentes * :) u thought that you know solution, but then you realized that actually it won't work?