PARTICLE TYPES
Making Elastics Particle Based Objects

Download Sample Scene


Vid1: Elastic

In this tutorial, we are going to take a look to how to make elastic objects using RF3 Particles.

First of all, we are going to define the two basic types of Elastic Objects you can create within RF:

  • Emitter based Elastic

  • Obejct Geometry based Elastic

The Emitter based Elastic uses the standard volume emision of RF3 emiters to create an Elastic Particle structure. The properties of thess elastic particles are exactly the same as the object based geometry but we can just mesh those particles with the RF3 mesh utility.
With the object based technique, we can use the geometry of imported objects as particle containers. What's more, we can deform the geometry by attaching particles to its vertex so we dont need to mesh those particles because we can export the object geometry deformation back to our 3D package.

In this tutorial, we are going to focus on the second ones.
In our scene we have a baseball bat, two walls, and the ball. We want the ball to hit the wall as the result of the impact with the bat.
Our bat is hand animated within RF3, matching the ball position. As you can imagine, aright now, it's just hitting the air :).

Then we choose a Fill-Deform Emitter from the emitters drop-down list.
The Fill-Deform is a special type of emitter that loads Elastic particles as default.


Fig1: Fill-Deform parameters

At this point, we can set up the Fill-Deform emitter in different ways. We can just fill the entire object with particles, make a selection of vertices or a mixture of both methods.
In images Fig1 and Fig2, you can see the difference between a selection of all the vertices and the entire object filled, plus the selection of all the vertices.



Fig2: Vertex Deform Particles



Fig3: Vertex Deform Particles plus Fill Particles

As you can imagine, different setups produce great diferences in the behavior of the elastic. Even with the same parameters, you will notice that the Vertex based one looks softer than the filled one. That´s because we don´t have any internal structure creating the illusion that the object is not just a cloth.



Fig3: Vertex Deform Particles behavior



Fig4: Vertex Deform Particles plus Fill Particles behavior

In images Fig2 and Fig3, you can see the diference between just vertex deformation and Vertex deformation with filled volume for the same elastic parameters.
As you can see, the vertex deform method creates more spongy systems than VD + Fill Volume.


TIP : If you need a tough area or volume in an object and you don´t want or can´t fill it, try to create a polygonal substructure to support the surrounding geometry. Fig5 and Fig6 show how an internal substructure can help you to create more solid objects. As you can see, when no substructure is applied, main springs are much wider than if applied. That gives the vertex much more movement and gives a softer look.
By applying a substructure, we can make those springs smaller and also create a new support spring. Now the vertex can´t move as much as before even with the same elastic parameters.



Fig5: Non SubStructured Object



Fig6: Susbestructured Object


The overall springiness of the particle system is controled within the Spring parameter tab. The higher the value , the tougher the particle system will be.
Vid2 shows you and example of the same particle system but 10 times less springy.


Vid2: 10 times less springy elastic


Although it´s not used in this tutorial (We have left out default value), another insteresting parameter you need to know about when making elastic systems is the Damping factor.
The Damping value is the intensity and velocity of the force that travels along the springs. Low Damping values make the forces propagate faster than higher ones. Take care with low damping values, it can produce system unstability.



Fig6: Damping value

The final result.


Vid3: Thas all folks!

 

TIP: Why don´t you try to hit the ball twice :)