CG Integration – 1 – Problems With Grains

I have been spending my time setting up a basic POP grain simulation. In the end I would like to have the ball roll into scene, knock into a sand castle or other grain form, and have it knock over and break apart as the ball is dampened by the inertia of the grain creation.

The main problems I have been having so far:

• Mass/inertia interaction between the colliding RBD object and the POP grains
• Grain object not holding its form completely
• Proper materials and coloring of the particles (not that important right now, but something to think about)

This is my Dop Network setup so far. We have a sand castle with a grain source node set on it. A sphere is currently being shot into the sand castle to awaken and collapse the particles. Extra nodes are explained below.

Grain source node, the only notes to make here is the Compute Mass function. This is to set mass to the particles computed from the final particle pscale, value of density measures in kg/m^3, 1000 is equivalent to water. It may be necessary to create an explicit constraint network to make sure that points pull one another down  and altogether holds together to keep the form of the sand castle.

POP Awaken node to wake the particles as the RBD sphere comes in contact with them as a work around for the particles not being able to hold themselves up and together but as the sphere comes in contact the entire castle collapses anyway. This solution, although it seems to work on the surface, causes way too many problems when actually implemented.

Custom colors in a POP Wrangle node. I am still experimenting with various settings, but this is mainly to change the value and/or saturation of areas of the sand that are more “sticky” (and therefore more “wet”) with a ramp to affect the distribution of this color effect and really isolate those wet sections of sand.

Grain update settings.  As you can see I have set the stiffness settings necessarily high, hoping to compensate and hold the sand together, as well as just experiment. However it didn’t result in much change, as stated before, an explicit constraint network seems to be the solution to all my problems and I will be testing it later today and tomorrow.

Basic sphere RBD being shot into the sand castle. I wanted to make a sort of beach-ball, floaty effect to test out the grains pushing back against and resisting movement but I have been having trouble attempting to achieve this effect.

Next post I should have a play-blast of a simulation, a constraint network seems to be the best idea right now to hold structure, but with weaker strengths so that it is also semi-easily broken. I have it all in a simple studio lighting scene and will hopefully be able to put it in the real scene soon. I need to work on the materials more for better integration. I’m staying at rather low res right now so I can test various different settings, but when I start to get more refined I’ll start bumping it up.

 

 

 

 

Grain Tutorials:

https://www.youtube.com/watch?v=pV6HJKM1XZo

Sand Destruction Reference:

https://www.youtube.com/watch?v=H-dpDmVF4RU

Sand Castle Model Uploaded by User LilyValley807 : https://www.models-resource.com/pc_computer/sims2/model/19676/