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I am trying to understand how to make fire in Blender. I bumped into this blog and downloaded the attached blend file.

In this blend file the Smoke Domain Material is constructed using two textures of the Voxel Data type. These two texture are called Flame and Smoke Density.

After the helpful answer of Josh I understand now that the way the Smoke Domain Material has been set up in this blend file is very Blender Internal (which I don't understand). Would somebody like to have a look at this blend file and reconstruct this Blender Internal Material into a Cycles Material ??

In the Blend file a plane is the Flow Object. The flow type is set to "Fire". This suggests that there is no smoke emitter ...but I think there is a smoke emitter.

Here is an image of the animation at frame 150 with Flow Type = Fire

enter image description here

And here is an image of the animation at frame 150 with Flow Type = Smoke + Fire

enter image description here

As you can see there is only a tiny bit more smoke when using the Flow Type = Smoke + Fire. So it seems that there is a smoke emitter in this blend file (when set at Flow Type = fire). By the way, also the manual says:

Fire Emit only fire. Note that the domain will automatically create some smoke to simulate smoke left by burnt fuel.

So I guess in the set up of the smoke domain material both voxel data Flame and Smoke Density should be used.

P.S I have studied the manual, I have seen the tutorial of Blender Guru. But this file produces a lovely fire and I want to understand this specific Smoke Domain Material set up. Maybe the quality of the fire is not only a result of the material set up but first things first.

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To convert a BI fire simulation volume shader to cycles, you don't need to change the simulation itself (domain physics settings). Just change the engine from BI to Cycles. Then Change the domain material to nodes, using the same color ramp (position, hue, saturation, value, alpha) for color. I doubled the emission (5 in BI, 10 in cycles). Don't forget to convert the light to nodes (there is a point light that has an effect on smoke)
cycles-BI compare

This is the fire+smoke cycles material, with some tweaks (frame 81). Final cycles material
The B&W flame color ramp uses the alpha from color as value.
The "density" is used for smoke density (voxel data) and "flame" for fire density.
The color attribute is not used here (white volume shaders) because the simulation uses only 1 smoke color. This attribute controls the smoke color and is useful when you have 2 or more smoke emitters with different color to get the color mix in the simulation.
frame 81 cycles

Here is the .blend file :

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  • $\begingroup$ You'll notice i've also changed the step size, but it increases render time. I'v also changed the corresponding max step to the lowest possible value. $\endgroup$ – Bithur Oct 26 '16 at 4:38
  • $\begingroup$ @OldMan In render settings, steps are kind of depth layers (or depth resolution). Step size is the depth of each layer and max step is the max number of layers the render will go through. More max steps (higher number) and thinner layers (low number) will make your volume render more precise at the cost of render time. $\endgroup$ – Bithur Nov 21 '16 at 16:55
  • $\begingroup$ hi, I have now rendered your file. I have at 200 samples but I have set step size and max steps at default values. Still for 250 frames it took about two days of rendering on my GTX970 and. I used the Wide Dynamic Range Transforms for Color Management. $\endgroup$ – Old Man Nov 28 '16 at 16:57
  • $\begingroup$ I have two questions. First, is 200 samples really necessary ? I am now testing to see if 100 will do also. I guess there are no other ways to reduce render time but maintain quality ? $\endgroup$ – Old Man Nov 28 '16 at 16:59
  • $\begingroup$ The other question is this: some parts of the plane stay black, they do not emit fire. How come ? I would expect the fire to be at all locations of the plane ? $\endgroup$ – Old Man Nov 28 '16 at 17:00
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This Blender Manual has the material setup for fire which is the standard one. Standard Fire Material

Node Setup

This is the setup on the Manual.

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  • $\begingroup$ I know but I want the Smoke Domain Material of this file. I have studied the manual, I have seen the tutorial of Blender Guru. But this file produces a lovely fire and I want to understand this Domain set up $\endgroup$ – Old Man Oct 22 '16 at 12:23
  • $\begingroup$ I really appreciate that you try to help but you don't answer my question $\endgroup$ – Old Man Oct 22 '16 at 16:22
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In Blender Internal every material is configured in the properties panel, not in the node editor. When different materials are created, they can be combined using nodes; in your file the nodes are used only for compositing purposes (glares, color correction). To analize your material, first of all play the animation so that the smoke/fire simulation is created. Then select the smoke domain, go to the properties panel and select the material tab.

enter image description here

After selecting the smoke domain material you can select the textures tab to see in the "influence" section which are their effects.

enter image description here

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  • $\begingroup$ if I use the Node Editor in Cycles I can add Attribute Nodes with the attributes color, density, flame ... are these in fact the same as these textures flame and smoke density ? $\endgroup$ – Old Man Oct 20 '16 at 13:44
  • $\begingroup$ How would you reconstruct the smoke domain material in Cycles ? $\endgroup$ – Old Man Oct 20 '16 at 14:10
  • $\begingroup$ hi Josh, It's probably a bit too much to ask to construct the smoke domain material in Cycles. Anyway, thanks a lot !! $\endgroup$ – Old Man Oct 20 '16 at 21:20
  • $\begingroup$ Sorry, I tried but didn't reach something good, I will try later on! $\endgroup$ – josh sanfelici Oct 21 '16 at 7:02

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