Spreading fire

I’ve followed the various fire tutorials found on the net and got my basic fire going. What I now need to have is a fire spreading over an area.
I need to have a paper burnt, starting in one corner, then spreading out over the whole paper. Websearching it seems that I need to use a gradient texture but I haven’t found any good source on how to do this.

Do anyone know of any good tutorial or have any good pointers?

If presented with this task I would look at it this way. 3 objects. 1-Paper not burnt, 2-paper burnt, and 3-fire.

I would have a gradient texture controlling the alpha of both pieces of paper, the texture controlling these would be inverse of each other, so while one was disappearing the other would be appearing. Animate the textures by key framing the ramp.

For the fire I would have a long thin plane, large enough to be the “fire line”. Then using shape keys I would “wiggle” the fire line around matching the edge where the un-burnt and burn objects meet (well where the textures controlling alpha meet)

If you wanted to get really fancy I guess you could burn the paper unevenly by creating a cool looking animated “burn line” mask rather than using a ramp texture.

take a look at dynamic paint

The paper bit I got covered. I have two versions, which I’ll mask and fade between, no problems there. It’s the fire I’m stuck at.
The effect should, rather than proper paper burning where very little is left, be that the fire spread out over the paper, not too dense so we still see the paper below, burn for a little, then die out. Leaving a scorched paper map/animation.
I need to control where as I have parts of the image that needs to be burned through revealing texts.
From web searching I find hints that I can do the fire spread by using a gradient texture where I paint the path I want the fire to take. Can’t find anything on how to actually do this though which of course must be out there somewhere…

Thank you! This definitely seems to be what I’m looking for!

I’ve played with dynamic paint a bit now and it looks like it might work. I’ve painted my paper full of cones ,which of course doesn’t look like fire no matter how much I squint…
I have a plane with a hair particle system with an object at each hair (cone), the lenth of the hair is affected by a brush weight so the cones grow. Great, exactly what I want. Except I want fire!
I’ve found a great fire to test with here: http://www.miikahweb.com/en/blog/2012/08/10/blender-fire-testing---blend-files
How can I use this instead of a cone for my hair particle Dupli Object?
I can’t get it to work no matter what I do…

I still need help, now a little more desperate…
How can I use more complex objects (a fire particle system) rather than single mesh objects for a hair particle systems?