# How do I prevent particle objects from intersecting each other and going though the floor?

The first step is to "throw" a group of steel tubes at a floor. They should bounce, and roll a bit. When they come to rest the next animated step begins: They will use shape keys to morph into an outline shape.

I am using an emitter, particles and a mesh cylinder. I've tried this with Collisions, and Rigid Bodies, looking for something that works.

Problem #1: The tubes come to rest but they intersect each other instead of resting on each other at odd angles. They should treat each other as impenetrable objects. Yes, I've set them with collisions.

Problem #2: The tubes pass partway through the floor, any axis, and appear to use their origin point to determine how far. This is more dramatic and more undesirable if they are rotated.

Problem #3: this is a variation of problem #2. The tubes bounce and stop >above< the floor.

Screen shots of problem 3. Settings are for the floor.

• It would help if you edit your question and add images of the settings you used.
– user1853
Feb 9, 2016 at 20:53
• related (possible duplicate): blender.stackexchange.com/questions/3421/… and blender.stackexchange.com/questions/5615/…
– user1853
Feb 9, 2016 at 20:57
• This seems like rigid bodies alone could solve the problem to get the desired effect if I understand it correctly. Is that not acceptable? Feb 10, 2016 at 7:11

I'm going to give this a shot as I think that rigid bodies are a viable solution. Start with a cylinder, scale it as needed but keep in mind that sometimes Blender can act strangely with objects that are too small with rigid body sims.

Next, add an array modifier, I used a count of 8, with an offset of 1.5 on the x and y axis, respectively. We are adding two identical arrays before applying them. The stack will look like this:

Apply the array modifiers in the order they were added, and Tab into edit mode, press A to select all, then P by loose parts. Now go back to object mode, it's time for physics.

Start by selecting your ground plane,add collision and then set it to passive in the rigid body settings(you can also go to the tool panel (T) physics>add passive).

Now select one of the cylinders, and again go to physics>rigid body> and set it to active. Now select the rest of the cylinders, and select copy from active in the rigid body setting in the tool panel.

With all of the cylinders still selected, press Shift+Ctrl+Alt+C>origin to geometry.

• Before you go any further, press Ctrl+A and apply scale to your objects to help prevent intersection between the collision object and other active objects.

Finally, place the group of cylinders where you want them to fall from/ be thrown from and start the animation. It may take some tweaking the rotation to get the perfect effect as they hit the ground, but it works pretty well. Don't forget that the mass of the object influences it's role in the simulation also, so you can play with that too if you like. After following these steps, you should be able to get something like the following .gif: Here is the .blend if you would like to reference it.