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## Popular Content

Showing most liked content on 02/17/2016 in all areas

1. 1 point

## Greeble plugin for Houdini

Hi guys, here is a new plugin for you: Hreeble https://www.youtube.com/watch?v=2hQzy26cGaw Finally we can build a Star Wars ships with a few mouse clicks! Source code and complied version for Houdini 15.0.347(Windows and OSX) available here: UPDATE: Update a video with some new features. Cheers, Alex.
2. 1 point

## Learning Crowds

I tried setting up the HIP and Feet on bretik's original file and it does not work. I believe the crowd system has issues with non biped agents. That is why I mentioned the particle approach in the other thread. It is still possible if someone can figure out the math. Basically we need an orientation formula based upon the normal of the terrain. A VEX math wizard.
3. 1 point

## Greeble plugin for Houdini

Thanks Alexey. How do one install plugins like this in Houdini?
4. 1 point

## Greeble plugin for Houdini

Creating your own greeble tool is one of the first modeling exercises you can do in Houdini, its fun. Your implementation looks nice in the video though . Just wondering, what does it do with triangles? I know that is also not a trivial problem to solve, especially if the method uses some kind of deformation, I don't think I have yet seen an implementation that handles it well, so no biggy you can also use the creep sop to do the last part. In general you want to avoid using foreach sops whenever you can, unfortunately that does often require you to use more math. But for perfectly rectangular shapes you should be able to use a copy sop with some point scaling.
5. 1 point

## Pyro upres advise.

Here's a nice thread on gridless advection with some examples: http://forums.odforce.net/topic/16415-gridless-advection/page-2 Jerry Tessendorf even has the last word!
6. 1 point

## Crowd trigger idea

Ah, it looks like the path to the grid geometry isn't quite right. You can either do "op:../../grid", since the path can also refer to files on disk, or (the better approach) use the Inputs tab to set e.g. Input 2 to the SOP path, and then use @OpInput2 in your VEXpression (see attached)
7. 1 point

## Crowd trigger idea

In your case it sounds like the goal point number for each agent is the same as its own point number? So it should look like: float tolerance = 0.5; vector goal_pos = point("../grid", "P", @ptnum); i@trigger = (length(@P - goal_pos) < tolerance);
8. 1 point

## Crowd trigger idea

You should be able to use a custom VEXpression trigger with a condition something like length(@P - point("/path/to/sop", "P", target_ptnum)) < tolerance
9. 1 point

## Animated Spot starring Mantra

Here's a few images for print campaigns as well.
10. 1 point

## Accessing voxel grid data

You can use Volume Reduce SOP to calculate the min/max values in volume primitives. You can also set it to store these values in primitive attributes to make them easily accesible in Attributes Spreadsheet / Details View.
11. 1 point

## Curl noise in VOPs and POPs?

Yeah, generating convincing fluid motion procedurally can be really tricky. The curlNoise VOP is really just using the vector curl of a smooth noise field to generate a divergence-free turbulence field, but that doesn't necessarily looks like fluid motion by itself; it just gives you turbulence with no clumping and no "gutters" in the velocity field. In the original Bridson paper, he procedurally generates potential fields that mimic fluid motion, vortex rings and flows and such, then adds the noise on top as turbulence and takes the curl of the summed potential field. Doable in VEX, but certainly not trivial. He also uses a variant of Perlin Noise called Flow Noise as the potential function, that tries to give the turbulence a more swirling-fluid motion. Houdini's implementation doesn't use FlowNoise, FWIW. Some recent research seems to focus on adding divergence-free turbulence on top of an existing low resolution fluid sim to boost the apparent resolution of the sim - since the sum of divergence-free vector fields is also divergence-free. You can do this using the CurlNoise VOP to add turbulence to particles being advected by a lo-res fluid sim. The trick is to apply the turbulence in a way that looks like its naturally occurring and evolving. That's what this paper and this thread are about. Anyway, unnecessarily long way of saying, you're absolutely right CurlNoise by itself is not a magic bullet for convincing procedural fluid motion.
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