Tutorial 08: Render Warps

 

FumeFX comes with unique feature that allows you to apply deformations like Bend, Twist, Wave, etc to the cache. In this tutorial we will go through all Render Warps parameters and see what they do.

 

In Maya, select File - >Open Scene, and from your [MAYA]/FumeFX/Tutorials folder, select the file Tut_08_start.ma.

 

Adjust Default Output Path and click on Start Default Simulation, to simulate first 50 frames.

 

The result is a nice smoke stack that is colored by the Object Source Color Channel Noise Map.

Imagine the following situation - Your smoke stack looks nice and you're happy about it, until your VFX supervisor comes in and says that he'd really need a smoke stack leaning to the right side of the screen and he needs it “on the desk” in 10 seconds. Until now you were able to do it by using a weak Wind effect, but you'd probably have hard time meeting the deadline as you need another night to run the high detailed simulation

 

For the purpose of this tutorial, we are going to add exaggerated effect, but generally, only small Deformer tweaks of the cache will look natural.

 

After the simulation is done, position time slider to frame 25. In FumeFX Attribute Editor, scroll down to the Viewport rollout and enable Display Always checkbox.

 

With FumeFX selected, select Deformation tab from the Maya Shelf and create Nonlinear Bend.

 

 

For bend1Handle set Translate to 0,0,0 (in Transform Attributes).

Within the bend1 Attribute Editor set Curvature to 10 and Low Bound to 0.0.

 

Open the FumeFX Preview Window and scrub the Maya's Time Slider.

You will notice that the smoke is now bent by the Bend modifier and despite its deformations it still looks pretty smooth.

Inside the FumeFX Attribute Editor, select Rendering rollout and notice that under Rendering Parameters rollout there is a group of options to control Render Warps.

 

Applied deformations can cause various artifacts, but with Supersample Min/Max parameters you can smooth out the final result. Higher deformation will require more supersamples to avoid rendering artifacts.

On the left Preview Window screenshot Min and Max are set to 1 and 2 respectively, while on the right image values are increased to Min=16 and Max=32.

 

 

Volume distortion has another artifact that is not so visible from the example above.

 

We're now going to detach Bend deformer from FumeFX. To do so, please open Deformer Sets dialog (Widows - >Relationship Editors - >Deformer Sets).

 

Inside the left list box (Deformer Sets), select bend1Set and it will automatically select its dependencies inside the right list box (Objects).

In the Objects list box, click on the fumeFX1 to deselect it.

 

 

IMPORTANT: In order for Deformer Sets Relationship Editor to operate properly, it is crucial to select the FumeFX grid before opening it!

 

Select FumeFX grid and from the Maya Deformation shelf click on the Nonlinear Flare icon to create it and assign to FumeFX grid. Set flare1Handle transform to (0,0,0). Set its Lower Bound to 0.0, End Flare X to 2.0 and End Flare Z to 2.0.

 

For a start disable the Auto Scale Density.

See how the smoke stack looks good with a widened top portion from Flare. However, if you look closely at the top of the smoke stack, you can notice that smoke is more transparent and colors are not so strong.

This happened because the top portion of the smoke was expanded significantly and everything inside the grid is actually “diluted”.

 

To preserve the look of the original smoke, FumeFX Render Warps have an Auto Scale Density parameter that will analyze deformations and add a correction factor to the equations.

Enable the “Auto Scale Density” parameter and notice that the smoke stack will retain its opacity and color from the original, non - deformed grid.

 

IMPORTANT: It is not possible to see Render Warps effect in rendered images directly. You will need to use Post Processing Simulation mode with enabled10

Bake Render Warps option and then render Post caches