Leaderboard

Not long ago I was tasked with a simulation of bags of hard candy falling and splitting open on the floor, with the candy of various shapes and sizes spilling out. This turned out to be way harder then I thought. There is really no built in way for vellum and bullet dynamics to interact with each other in Houdini. After searching the internet, I did find one tutorial on kind of faking the interaction, but it seemed overly complicated to me. So after a bit of R&D I came up with this setup. Its very simple and fast, and solves both the vellum and bullet sims in one network at the same time: It basically works by importing the RBD geo into the vellum collision solver, and the vellum geo into the bullet solver. The mass of the RBD has to be faked in somewhat, so it interacts with the cloth in a more realistic way, but that's it! See hip for example: vellum_x_bullet.hip

This is Procedural Design in Houdini . Everything is generated, on the fly with PDG and custom process and algorithm from the head primitive. This is not a render by the way, just OpenGL capture Sorry after upload , i realized my animated GIF seem not accepted by the server, image is not updating, and i can find a way to delete my post... ________________________________________________________________ Vincent Thomas (VFX and Art since 1998) Senior Env and Lighting artist & Houdini generalist & Creative Concepts http://fr.linkedin.com/in/vincentthomas

Most visual effects are a combination of multiple elements, you may want to use more than one approach. Fast moving in one direction and swirling are kind of opposite requests. You can just shoot particles in a direction and rasterize them into a fog volume. One approach to thick fog is to zero out Cooling Rate and Temperature Diffusion on the smoke solver. ap_atmospheric_dust_mist_102419.hiplc ap_running_through_thick_mist_102519.hiplc

@kurzemnieks something like this ..but you need to tweak in particles source those parameters "its already time consuming" for me . part.hiplc

Ok gotcha : As effective changes in stiffness requires painting over orders of magnitude, this has a logarithmic effect. i don't exactly know what it is , but i'm sure it explain the problem. houdini doesn't do a scale with a basic mult but instead use logarithmic math. anyway i don't like it cause it introduce unexpected value that i have not ask. i will use the wrangle option to be sure to control exactly the value i want. Cheers

Vellum Paperbag Smashes RBD Concrete ball Note: be sure to hit Reset Sims after you've changed any params in CTRLS Devastating Spinning Kick vu_SteelBall_vs_PaperBag2.hiplc

Hi, in Houdini, similar to Maya as I thought, you can think about two or even three languages: 1. Languages: - Hscript (look for help in Texport via "help") - Expressions (look for help in Texport via "exhelp") - Python -(gosh, lets add the forth: VEX) 2. Differences in use: - Hscript executes commands (add operator, delete, rename, link) - expressions computes a value (compute angle, matrix etx) - (Python does both) - (VEX modifies variable's value like point position, surface colour, pixel value etc) 3. Backticks usage: - backticks allows you to place expressions in hscript... - or execute expression in a parameter that does NOT expect numeric value (like string parameter) for example, in file input path, you could write: op:/`opinputpath(".",0)` or: ./my_great_texture.`padzero($F-10)`.rat since this input file field expect string and it couldn't recognize padzero() as an expression in other way. But in case of translation parameter you need just an expression: fit01(rand($PT), 0.5, 1)) without backticks, since a parameter expects numeric value anyway. So: - using expressions inside hscript requires `` - you also need `` to evaluate an expression in non-numeric neighborhood, like strings, paths etc. - but you don't need it if expression is evaluated in numeric parameter. - you can also in opposite use hscript in expression with "run()" or "execute()" functions. - both expressions and hscript are accessible in Python with hou.hscript() or hou.hscriptExpression() (Unless they have pure equivalents in Python like opadd == hou.createNode() ). hope this helps, Simon. PS There are also expressions returning strings like points(), chs() and they need backticks also to be executed in parameters but not taken "as is".