burrowing under a brick road

[cspears2002]

I created a brick floor. Now I want to create the effect of something burrowing underneath the bricks (just like Bugs Bunny)! I animated a ball moving through the bricks and then turned the ball into a rigid body and the floor into an inactive rigid body. Unfortunately, the ball either flies over the bricks or doesn't do anything, i.e. it just sits there. Any hints? I attached the scene file to this message.

brick_road_v07.hipnc

[3__]

try using sops only. much faster.

burrow.hipnc

[jason_slab]

nice example cpb! thx for posting

jason

[dan_j]

I agree, thats a sweet example post. Thanks man

D

[MrGAG]

yes, simple, effective, pretty straight forward setup . Bravo !

it gives me a lot of ideas ...

Edited September 8, 2008 by MrGAG

[cspears2002]

Thanks for advice! I am well on my way! However, I have two issues that need to be resolved.

1) Some of my bricks are interpenetrating.

2) There is a weird "shifting" in the surface. I'm not sure what is causing this. Any ideas?

brick_road_v09.hipnc

[anim]

...

1) Some of my bricks are interpenetrating.

2) There is a weird "shifting" in the surface. I'm not sure what is causing this. Any ideas?

...

it is caused by the magnet SOP's scale

also your metaball is aligning to the curve and has no upvector, it can cause flipping and many problems

I slightly modified your file (created nodes are in RED, modified in GREEN):

turned off Transform using point attributes on copy2 SOP - to prevent metaballs from aligning, they are spheres, so it is not visible anyways

tweaked parmeters in Magnet SOP - no scale, only pos Y

created up vector parameter for the bricks - bypass it to see the effect

created facet SOP to compute normals after deformation - bypass it to see the effect

you can introduce some randomness into the rotation of bricks by copystamping later

brick_road_v09b.hipnc

[anim]

here is the example of some variations by copystamping

again changes from previous file red/green

and i changed brick geometry only for performance reasons

brick_road_v09c.hipnc

[cspears2002]

Thanks! I have been adopting what you have shown me into my network. I do have a question about the AttribCreate SOP. Looks like you used this to create a vector pointing along the Z axist in order to orient the bricks correctly. I am surprised that you don't need to do anything special for Houdini to figure out how to use the vector.

I downloaded the AttribCreate sample network. In that network, a point attribute is created called width, and Houdini automatically used the variable to generate geometry around the points to copy a texture to. Again, Houdini didn't seem to need any special prompting/

Is Houdini really that smart or am I missing something here?

[anim]

there are certain attributes which houdini can use automatically when the node is expecting it (like "up" i used)

for example look in docs at (Copying Instancing point attributes) http://localhost:48626/copy/instanceattrs

also you can override VOP/VEX parameters by attributes

when you create VOP node with the float parameter called "height", this parameter can be overriden with the float attribute "height" on the input geometry

[old school]

The point sop has most of these default attributes available as default parameters. The up vector attributes are in the particle folder.

There's are three ways to make the up vector easily: point sop, attribute create sop, VOP sop and Add Attribute VOP. Thelast two options require you to set the correct type which is vector.