I am having an issue with rendering fire on a transparent background. I’ve gone into the world and changed the alpha from the sky to transparency. I’ve checked the transparent box under the render properties, under the film section. However, when I do this only my emitter renders, not my fire simulation. Unchecking the box under the film section causes renders to return to normal. Any help would be appreciated. Thanks!
did you resolve it ? I am stuck on the same issue.
Hopefully he figured it out. The values for the fire are still there, they just aren’t visible with the way blender displays them by default. My post here explains a bit about why this happens:
If you export the image in a file that supports premultiplied alpha (such as .exr), those values will be there and can be properly composited.
For a bit of added clarity, fire should not have an alpha value. It’s a transparent but emissive material. This means in a proper alpha over compositing operation, the RGB values of the fire simply add to those they’re being composited over.
TL;DR The fire is there, blender just isn’t showing it to you by default. Use the viewer buttons to be able to see it.