I’d like to memorize the configuration parameters of dForce.
First, I’m going to try the store-bought dForce hair.
The dForce is a physical simulation of cloth and hair.
You can also use tools that add artificial movement to the fabric, such as letting your hair flow in the direction you want, fluttering your skirt, or taking off girl’s pants.
The dForce parameters are scattered in the following three places.
- Tab of Simulation Settings
- Simulation at Tab of Parameters
- Simulation at tab of Surface
- Simulation Settings General dForce parameters such as gravity and simulation time
- Set the physical attributes of the Simulation object in the Parameters tab
- Setting the physical attributes of each simulation surface group on the Surface tab.
- Parameter recipes to shorten simulation time
- dForce-enabled clothing – just simulate and auto-fit
- Summary of dForce
Simulation Settings General dForce parameters such as gravity and simulation time
The general parameters of dForce can be adjusted in the Simulation Settings tab.
- Gravity Gravity, which is 1.0 and equal to the gravity on earth.
- Air Resistance Air resistance. The higher the value, the slower the drop speed.
- Initialization Time Initialization time. Hmm?
- Start Bones from Memorized Pose Whether or not to start the simulation from an initial pose. In a pose where the human body is violently penetrating the clothes, turning this on will smoothly deform the clothes.
- Stabilization Time Stabilization Time?
- Frames Per Second (FPS) Mutiplier FPS coefficient?
- Subframes Number of simulations per frame?
- Iterations ( Per Subframe ) Number of simulations per subframe.
- Polygon shape used for collision mesh resolution.
- Colision Mode Prediction mode.
- Collision Iterations ( Per Subframe ) Number of collisions per subframe.
- Translated with www.DeepL.com/Translator (free version)
Ref)dForce daz forum
Set the physical attributes of the Simulation object in the Parameters tab
Parameters of General->Simulation, such as physical operation type
- Static Surface Solids that do not deform and are not affected by gravity Animation is possible in TimeLine. Friction and collision become effective.
- Dynamic Surface Deformation, a fabric object affected by gravityDynamic Surface Add-On Connects fabric objects to each other.Simulation Object Type Handling in simulation
- Use Simulation Start Frame Determine the first frame according to the Simulation Settings.
- Use Scene Frame 0 Use frame 0 of the timeline
- Use Shape from Simulation Start Frame to morph the starting shape to match the SimulationBase_ object name. The frame is determined according to the contents of Simulation Settings.
- Use Shape from Scene Frame 0 Make the starting shape a morph that matches the SimulationBase_ object name. The frame is determined according to the contents of Simulation Settings.Simulation Base Shape
- Temporarily treats the target object as a “Static Surface”. This may be useful when you want to run a simulation for each object.Freeze Simulation
Parameters of Display>Simulation Physical Simulation On/Off
- When Visible in Simulation On is selected, it is treated as “nothing” in dForce simulation. It won’t crash, deform or fall.
Setting the physical attributes of each simulation surface group on the Surface tab.
- Visible in Simulation Whether to simulate it or not
- Friction Can produce a slippery feeling of silk to a rough feeling of leather and denim
- Density (GSM) Density The effect of air resistance varies from 30 to 150 Lace linen 150~350 Satin, velvet 350+ Denim, etc.</li
- Contraction-Expansion Ratio More than 1.0 makes it easier to stretch and less than 1.0 makes it easier to shrink; less than 1.0 makes it easier to fit the body.
- Shear Stiffness (Quads): Shear stiffness is less likely to strain and twist when the value is highBend Stiffness The higher the value, the larger the crease, the stiffer it feelsBuckling Stiffness buckling stiffness Higher values make it harder to shrinkBuckling Ratio Buckling Ratio The larger the value, the easier it is to turnSimulation/Structure
- Dynamics Strength The magnitude of change in dynamics strength. It is better to lower the value if you want to keep the shape
- Stretch Stiffness The higher the value, the harder it is to stretch
- he larger the Damping damping value, the faster the overall motion of the deformation will be absorbedIf you increase the Stretch Damping value, the swaying of stretch deformation will be faster Simulation/Structure/Damping
- As you increase the Shear Damping value, the swaying of strain-twist deformations is faster to be accommodated
- If you increase the Bend Damping value, the swaying of the bending deformation will be absorbed faster
- Velocity Smoothing Acceleration smoothing Smoothing large, rapidly moving objects (easily exploded)Velocity Smoothing Iterations The number of splits of accelerated smoothing. The larger it is, the less likely it is to penetrate or explode, but the slower it will be.Simulation/Smoothing
Simple setting of physical parameters with dForce Surface Adjuster
The setting of physical attributes is complicated, and at first glance, I have no idea what it is. So, there is a tool for a simple configuration.
The following configuration screen appears.
If you tweak only three parameters, the system will automatically replace them with fine parameters.
- Stiffer Hard ←→ Silker Soft
- Shrink (shrink) ←→ Expand (expand)
- Stretch Small – ← → Stretch + Stretch Large
Here’s the actual simulation with different parameters.
Increasing Stiffer makes the cloth harder to break and less wrinkled, while increasing the value in the direction of Silker makes it silky soft and deformed. Wrinkles can also be prolific.
Increasing the value in the Shrink direction makes it easier to shrink, and increasing the value in the Expand direction makes it easier to expand.
It’s hard to tell the difference when you use Stretch by itself, but when you use it in combination with Shrink or Expand, the “stretchability” changes. If the value is large, it will be stretched or shrunk, and if the value is reduced, it will try to return to its original state like a rubber. Maybe.
Note that each value is relative. If you first click the Shrink button five times, then close the screen, then open the screen again and click the Shrink button five times, it will be the same as clicking Shrink ten times.
The disadvantage is that I don’t know what the current value is, but I’m thankful that the results are reflected immediately.
Specify a weight map with dForce Weight Node Modifier
By specifying a weight map, it is possible to exclude fittings, hard parts, and places that do not want to be subjected to physical operations.
The target object is painted red. If you hold down the Alt key and trace the red area, the red area can be erased.
When a dForce simulation is run, all but red are out of the physical arithmetic range.
For the weight map, right-click on the scene with Node Weight Map Brush selected from the Tools menu at the top of the screen and select Weight Editing→Smooth Selected to create a gradation around the border.
Simulate button to start dForce simulation.
When the button is clicked, the load on the graphics board goes up, and it looks like Cuda, the 3D graphics processor, is bouncing around internally.
The graphics board is the NVIDIA GeForce GT 1030, which will be sold in 2020 for about 10,000 yen.
The GT 1030 is a fanless, quiet, and satisfactory performance for me, who switched from a 10 year old one. It’s also good that it doesn’t get hot even if you stick it into a compact PC with a narrow interior.
That said, the hair from earlier took about 8 minutes to simulate. It was going to take hours to get the simulation to the end, so I clicked on Cancel at the appropriate point to stop the simulation.
▲ It’s still going to take some time, but the look of your hair is almost unchanged
Unlike the rendering, I don’t mind if you don’t simulate it so strictly. Can’t I just tweak the parameters and make it do dForce simulation at high speed?
When I set the Frames Per Second (FPS ) Multiplier, Subframes, and Iterations( Per Subframe ) as small as possible, which seems to be related to the simulation time, there was an error at the beginning of the simulation.
How to check the error log
The log can be seen in the menu Help→Troubleshooting→View LogFile at the top of the screen.
When I repeated the simulation with these numbers, DAZ Studio terminated abnormally.
Parameter recipes to shorten simulation time
When you run a dForce simulation for testing, you may want to finish the simulation quickly and accurately. I tried a lot of things.
To reduce simulation time, reduce the number of Subframes
It seems that the parameter that can reduce dForce simulation time is Subframes, which reduces the accuracy but shortens simulation time.
I changed the subframes from 8 to 4 and it took me about 2 minutes to get a good feeling.
I set Subframes to 1, and the accuracy of the simulation result is quite questionable. The simulation is getting to a good point in a minute…
I feel like my bangs are falling down a little too much, but hmmm, not so bad?
The result of reducing hair polygons by Decimater, even if polygons are reduced.
Reduce hair polygons to 30% in Decimator and rerun the simulation.
Increase the number of polygons of hair to 30% (320,000 polygons to 90,000 polygons or so)
Changed from Collision Mesh Resolution to View port.
As a result, the simulation time was not much different.
It looks like the polygons have been reduced, but the amount of calculation done in the simulation seems to be the same. I wonder if there are other parts to modify.
dForce-enabled clothing – just simulate and auto-fit
It’s a trouser and shirt set, but with dForce applied, it fits the figure nicely. It feels good to fit a petite woman in a dapper, oversized shirt.
Here’s a look at the dForce-enabled clothes I’ve purchased. I want you to see the part where I’m like, oh, that’s how it fits.
Summary of dForce
- The dForce simulation takes so much time. In the case of hair, about 8 minutes.
- However, if you lower the value of Subframes in Simulation Settings, the simulation time seems to decrease.
- Decimator’s reduction of hair polygons did not change the simulation time