Appendix
Live Mode
Dimension
Values-Examples
Presets
Live Mode

Live mode allows to run the simulation at the current frame without running the animation.
You can use this to let the cloth reach a stable position at the first frame of the animation.
To put a cloth in live mode:
  • Select in the menu: Syflex > Live Mode
    This opens a new window.
  • Select a cloth
  • Click on start
    The cloth is now "living". You can tune any parameters while the simulation is running.
  • Click on stop to stop the simulation.
The simulation also stops if the window is closed.
Always stop the simulation before :
- Running the animation,
- Saving the Maya file,
- Working on another cloth.

Dimension

Syflex implements a simulator based on physical equations. Each parameter of the simulation has a physical meaning, and is expressed with specific units. These units are combinations of 3 base units:
LengthL
Time T
Mass M
This combination of base units is called the dimension of the parameter. Here are a few examples of dimensions:
Unit Dimension
Speed L/T
Gravity L/T²
Density M/L²
Spring StiffnessM/T²
Damping M/T
If a unit is changed, many parameters may be updated.
For instance, on earth the magnitude G of the gravity is G = 9.81 m/s². If your units are centimeters (1 meter = 100 centimeters), and frames (1 second = 30 frames) then the value for G must be:
G= 9.81 m/s² = 9.81*(100 cm)/(30 f) ² = 1.09 cm/f².

Go to the next paragraph for example of values, depending on the units you are using.

Dimensions can also be used in various situations:
  • if the cloth is scaled by 3, but you want to keep the same animation, scale the gravity by 3
  • if the frame rate is 25 frames per second instead of 30, this is equivalent to multiply the time units by 25/30=0.833. To keep the same cloth animation you should:
    • divide all spring stiffness values by 0.833²=0.694
    • divide dampings by 0.833
    • divide gravity by 0.694
Example of Values

In order to set appropriate values for the simulation, you need to know what the units used in your scene are. For instance, in the case of this simple scene consisting of a rectangular 1 by 1 meter piece of cloth:

If the cloth measures, in Maya units, 1x1, then you are using meters.
If the cloth measures 100x100, then you are using centimeters.
And if it is about 3x3 then you are probably using feet.

Here are a few examples of values, depending on different units.
In these tables, units are in: m(meter), g(gram), Kg(Kilogram), s(seconds) etc.

UnitsL=m T=24fps M=g
Gravity-0.017
Mass Density100
Cloth Spring Stiffnesses20
Cloth Spring Dampings0.2
Global Damping0.02

UnitsL=cm T=24fps M=g
Gravity-1.7
Mass Density0.01
Cloth Spring Stiffnesses20
Cloth Spring Dampings0.2
Global Damping0.02

UnitsL=cm T=24fps M=Kg
Gravity-1.7
Mass Density0.00001
Cloth Spring Stiffnesses0.02
Cloth Spring Dampings0.0002
Global Damping0.00002

UnitsL=cm T=s M=Kg
Gravity-981
Mass Density0.00001
Cloth Spring Stiffnesses11.52
Cloth Spring Dampings0.0048
Global Damping0.00048

If you have JavaScript enabled, you can use the following table to compute defaults values for your units:
your length unitL = meters
your time unit T = seconds
Your mass unit M = grams
Gravity=
Mass Density=
Cloth Spring Stiffnesses=
Cloth Spring Damping=
Global Damping=
For instance
  • if you are working with inches, put 0.0254 in the lenght unit field.
  • if you are working with centimeters, put 0.01 in the lenght unit field.
  • if you are working at 24 frames per second, put 0.041666 (1/24) in the time field
  • if you are working at 30 frames per second, put 0.03333 (1/30) in the time field
  • if you are working with pounds, put 454 in the mass field
The form uses the following formulas: 
	input : L (length), T (time), M (mass)
	gravity = 9.81*(T*T)/L
	mass density = 100*(L*L)/M
	spring stiffness = 12500*(T*T)/M
	spring damping = 5*T/M
	global damping = 0.25*M/T
The collision envelopes are sizes in "lenght units". For a character about our size 180cm (5'11") an envelope of 1cm (0.5") will give correct results.

Other parameters don't have dimensions, and don't depend on your units. This is the case for the following attributes:
  • Collision friction
  • Collision bouncing
  • Cloth precision
Presets

For each node, you can set default parameters.
You first need to check what units you are using (centimeters or meters, etc).
Then for each node you can find presets values, using the Attribute page:

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