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Great thanks!
@IceDragonArt The time today for the webinar is actually at 4 PM EDT, not 3 PM. Turns out England went off summer time last night while we are still on daylight savings time. Just wanted to be sure you knew.
Okay that's actually better for me. We have a memorial to go to at 2pm but we will be back by 4 - 3 would be cutting it a bit close.
Strength is force per unit area; stiffness is force per unit length.
That was a really great webinar Rich, I learned a lot. I will have to watch the first half yet but I learned a lot of very useful stuff today. Thank you!
And if anyone missed it, I hightly recommend you snag it when it comes to the Daz Store.
Thanks Sonya - glad you liked it. Hope your webinar next week goes super (and with no weather events!)
Haha ya, we had a hail storm right after we got done with the webinar lol. Hopefully it will be sunny and calm next Sunday.
More About Pillows. Almost everyone lets their head sink into a pillow at night but citizens of Dazland often find their pillows hard and stiff, unyielding to their heads. Here are a few examples of pillows that work.
a. One I’ve already shown early in this series of tutorials is from Modern Room Bedroom (see Getting a Figure’s Head to Sink into a Pillow). I was lucky I used that one as it dForced readily for two reasons:
(1) It has quad faces
(2) The lower polygons of the pillow are embedded below the surface of the mattress which locks them in place when negative gravity is applied. Too bad not all pillows are made like this. You can load these pillows as a prop, so they can be used in other scenes.
This pillow already comes with a depression. To fluff it up more, I used Simulation surface settings of 105% Contraction-Expansion Ratio, 100% Buckling Ratio, and Simulation Pane setting of -1 Gravity. Here's a finished render:
b. A second pillow is from The Breakfast Nook. Like many others, it has triangular faces which causes issue with dForce. It has also been somewhat deformed by the vendor who wanted them to look like they had been “in use”. Here’s what to do to use it with dForce:
i. Create a plane or cube to serve as a mattress. Load the pillow onto it and lower it so it penetrates into the plane or cube. Add a dForce dynamic modifier to the pillow.
ii. Next load and position a figure. You will see the pillow cuts right into the face. On the animation timeline, set the figure so the upper body is raised at frame 0. At frame 8, have the body lowered and turn the head to the side as shown.
iii. Add a dForce weight node to the pillow: choose Create/New dForce Modifier Weight Node. A new child weight node will appear in the Scene pane under the selected object. Select the new weight node object, and from the Tool Settings pane, select Node Weight Map Brush in the Active Tool drop-down box. In the lower section of the pane, choose dForce Simulation::Influence Weights in the unused Maps drop-down box then click on the Add Map button.
iv. The object will be red showing that the weights on the map are at the full strength of 1. Right click in the viewport and choose Geometry Selection/Select All. Then right click in the viewport and choose Weight Editing/Fill Selected and enter 0% to clear the weight.
v. Choose the paint brush mode (4th icon from right at the top of the pane, has a small P in lower right corner). Start to paint around the head until it becomes red again. Paint less on the surrounding area so it is blue. Use the smooth brush mode (3rd icon from right at the top of the pane, has a small S) along the colored edges to make the transitions smoother.
vi. The triangular faces will cause the mesh to explode. In the Surfaces pane, set Bend or Stretch Stiffness to 0.3. In the Simulation Settings pane set gravity to -0.1 then run the simulation.
vii. The head will have depressed the center of the pillow where the red was painted. There will be less deformation as you move towards the gray areas.
A finished render:
c. A third pillow is from Day in Bed. This one is tricky because although it is one object, it has a pillowcase around the pillow. There’s a mesh within the mesh that will create issues. It also has the triangular faces that cause problems with dForce.
i. Repeat all the steps in section b for this new pillow.
ii. After simulation, you will find that the interior part of the mesh (orange) has protruded through the exterior mesh. The interior has a different mesh design, in particular, smaller faces. Because the meshes have different size faces they behave differently. Plus when painting the weight map, it was applied to both interior and exterior as there is just one surface.
You may get away with this behavior if you have a single-color shader or material, but for most shaders you’ll see the interference as in this image.
iii. To correct this, we’ll first create a second surface:
iv. We could stop here if you set the camera so you don’t see into the gap on the left side.
v. If your camera does need to include the left side, you’ll see that the pillow is missing.
You can change this by hiding most of the interior:
In the Geometry Editor click on the eye icon for the Sheet surface to turn it back on. Run the dForce simulation and render the results.
I'm surprised these two examples of totally messy topology don't cause problems with rendering!
I was surprised at how elongated many of the faces were and the tangle of triads but that may be what's preferred for an item like this. Two different vendors too.
JCMs for clothing are not affected on dForce Simulation result?
Perhaps they were both from Marvellous Designer.
I'm not really sure how dForce and JCM's work together or not. I do know with regular morphs if you dial them in before a simulation, the simulation will deform them. If you dial them in at the end of the simulation, the mesh change is added on top of the simulation results.
Ok, I will start a new thread about that. May be somebody, who made cloth, will answer why they doing so many morphs for dForce clothing.
That would explain the mess, definitely. Or a sculpting program that does not have a strong retopo module.
63. Momentum Transfer
Some have asked if dForce can be used to cause a ball to bounce. It can’t (at least so far) but it can transfer momentum and cause an object to fly away. I first saw hints of this while testing a particular scene and then I changed Simulation settings and surface settings to enhance it. The animated gif shows what happens.
a. Create a torus of 1.5 inch major diameter and 1 inch minor diameter, Y-positive, 100 segments and 32 sides. Add a dForce dynamic modifier to it.
b. Create a cylinder 4 inches high, 2 inch diameter, 20 segments and 32 sides.
c. Set up a 60-frame animation so at frame 0 the cylinder is about a torus diameter away.
d. At frame 10, have the cylinder move forward and collide with the torus off-center.
e. Set gravity to 0. This means the torus will neither rise nor fall or move unless it undergoes a collision.
f. Set air resistance to 0. This removes drag and allows the torus after the collision to move farther and faster.
g. Set Buckling Stiffness to 100% and Buckling Ratio to 0. This will mostly keep the torus from collapsing in on itself when hit.
h. Set density to 10. This will make the torus surface stiffer.
i. Run the simulation. You will see the torus partially collapse when struck by the cylinder. Momentum is transferred to the torus, the torus’s surface will rebound, and it will fly away.
Frame 10: Frame 16: Frame 30:
Frame 60:
j. What is this good for? I don’t know but it suggests there may be a way to get dForce objects to bounce off surfaces.
Hmmm asteroids bouncing off a spaceship or cars off of other objects maybe
Wonder if both objects could bounce off each other
awesome find
Thanks. Right now it's uncontrollable with direction of movement unpredictable. I'll have to play with it more. It may be the torus shape is key to the rebound.
Maybe you can control the direction a bit by setting up two just not quite totally (Opacity = 0.0001) "walls" (made from square primitives), that add further obstacles in the way the doughnut bounces?
Firstly, a big Thank You for your superb tutorials!
(Secondly, thanks for the info on how you make your animated .GIFs actually animate in your forum posts)
I added a dForce 'Dynamic Surface Add-On' internal PolyLines structure to a ball to enable the ball to bounce like rubber instead of just flop like cloth:
See attached scene file Bouncing_Ball_01.duf
NB: Requires DAZ Studio v4.11.0.236 or later
The ball surface was made by sub-dividing a cube - this produces a sphere made of evenly-sized quads, which should behave better with dForce than the standard DAZ Studio Sphere primitive:
New Primitive: Cube
Origin = Object Center
Primary Axis = Z+
Size = 15 cm
Divisions = 1
Set Y-Pos = -7.5 cm
Edit > Object> Geometry > Convert to SubD
Parameters > General > Mesh Resolution > View SubD Level = 3
Temporarily Hide all other Scene Nodes, then
Export > Sphere.obj @ 100%
Delete Cube
Import Sphere.obj @ 100%, rename 'Ball':
In Joint Editor > Tool Settings:
Set Center Point Y=0
Edit > Object > Geometry > Add dForce Modifier: Dynamic Surface
The internal structure of polylines was made in Cinema4D, saved as an .obj file, and Imported into DAZ Studio with the "Read Polylines" option checked.
It consists of vertices coinciding with the vertices of the ball's Sphere.obj, each with a Line linking it to its symmetrically-opposite vertex.
It was Imported @ 100%:
In Joint Editor > Tool Settings:
Set Center Point Y=0
Edit > Object > Geometry > Add dForce Modifier: Dynamic Surface AddOn
Parent it to the Ball
Move the Ball to Y=150
Add a ground-plane as a collision surface
Run the Simulation.
It still needs a lot of experimenting with Surface settings, etc. to make it useful.
Great! I'll take a look at this.
To post an animated gif, it first has to be hosted on another site (I use https://giphy.com/upload). After uploading the gif, click on "Copy Link" to get the url for your gif. Then in your Daz Forum post, click on the source button and paste this code:
<p><a href="https://media.giphy.com/media/__your gif's url goes here__/giphy.gif" target="_blank"><img alt="" src="https://media.giphy.com/media/__your gif's url goes here__/giphy.gif" style="height:320
px; width:240px" /></a></p>
Adjust height and width as needed.
I just loaded up the scene. Very clever!! You can even see the ball deforming when it's hit. That was a good idea to use a quad cube and create the add-on structure. Your post is a good example of how add-ons and the new polyline capability can be very useful.
After trying out the scene as you created it, I added a moving cube into the scene and used it to hit the ball while it dropped and got it bouncing along until it fell off the plane.
Thanks for that info on how you make your animated .GIFs actually animate in your forum posts - it works well!
You work fast!
Used your idea of the "intruding cube" (attached Bouncing_Ball_02.duf)
(Updated Nov 20 to render in IRay)
With the added momentum, you're getting a good amount of bouncing. Definitely has the right look. Good job figuring this out. I'll add links to these posts to the index on the first page.
Bend Stiffness for Clothing Made with Trigons
So it doesn't get lost, I wanted to post a link to this thread from Aave Nainen. She mentions setting bend stiffness to 0.3 or lower on her older clothing products to help them dForce better. There's also a link further down the page to several ShareCG files for specific clothing items of hers (although the bend stiffness hint may replace the need for them). AN also posted these hints in another thread to prepare clothing for better dForce'ing.
The basis for her recommendation comes from the fact the clothes are mostly made with trigons (see attachment for an example). As I've shown in previous posts about sphere and cylinders, objects made with this type of polygon will explode unless you set bend and/or stretch stiffness low. You can apply AN's recommendation on bend stiffness to clothe items made by others if they use trigons. A low bend stiffness does not guarantee success but goes a long way towards achieving it.
A video tutorial that goes along with much of the material that Richard has been sharing in this thread has now just been released in the store.
https://www.daz3d.com/powerful-dforce-discoveries-and-solutions
i'm thrilled to pieces that I got Rich's tutorial today. I've been a faiithfull follower since the beginning and have followed many tutorials, but it's nice to have them in this format. Thanks Rich for being such an awesome teacher and for sharing your knowledge here with us. Hope it's not going to stop you from adding things to this thread though!
Look forward to the next book.