Tutorials | A Pile Of Grains This post will try to explain how to write and install your own VEX DSO plugin for Houdini, written in C++. The included example project creates a plugin called VexImageReader. This plugin can be used to read all sorts of images, including psd and dds files. The reader can be used in all vex context layers and is added as a function called: readimage. The function takes as input arguments a U and V coordinate, an input string (image name) and a wrap mode. Before we start, download the necessary files right HERE. The source code and Visual Studio 2008 project file (code)The FreeImage library source code (freeimage/Source)A compiled x64 windows DSO (build)A compiled x64 windows FreeImage library (freeimage/Dist)An otl that wraps the Vex function call in to a VOP (otl)An example HIP file (hipfile)The VEXdso include file, used by Houdini to add the VEX plugin to the houdini DSO table. As mentioned above, I included the compiled plugin. The code should be cross-platform compatible. Links
OpenVDB The Science of Fluid Sims Fluid sims have become such a vital part of so many visual effects films, yet are not well understood by most general artists. We try and explain the science behind the fluid sims, and look at one in particular closely: Naiad, with help from our friends at Exotic Matter. Introduction One of the most significant and commonly requested areas of real world simulation is fluid simulation. Fluid sims are not confined to just fluids either, they can be used to achieve fire and flames - the fluid being simulated in this scenario is the air itself (a gas). Fluid simulations (fluid sims) have many applications outside visual effects. History Before the computer graphics industry got involved, fluids simulation was being actively modeled mathematically as early as the 1950's and 60's. Unfortunately, most methods for real world CFD are needlessly complex for visual effects fluid sims and scale poorly. - Watch Jerry Tessendorf talk at TED. - A Naiad scene test: 'Bunny in Trouble' Basic concepts
Deforming RBDs Simple setup that uses a SOP solver and deforms the geo at points of impact. The impact data is already available in the SOP solver, the normal is the impact direction and there is a pscale attribute for the magnitude of the impact. In this setup I just used attributeTransfer to get the impact data onto the mesh, then a vopsop to deform the mesh. Houdini - Impact deformation for RBDs from Sam Hancock on Vimeo. Also going to try getting some volume preservation going on! Art of Destruction (or Art of Blowing Crap Up) Destruction pipelines today are key aspects of any major visual effects pipeline. Many current pipelines are based on Rigid Body Simulations (RBS) or otherwise referred to as Rigid Body Dynamics (RBD), but a new solution – Finite Element Analysis (FEA) – is beginning to emerge. In this ‘Art Of’ article, we talk to some of the major visual effects studios – ILM, Imageworks, MPC, Double Negative and Framestore – about how they approach their destruction toolsets. In VFX and CGI, RBS is most often relevant to the subdivision of objects due to collision or destruction, but unlike particles, which move only in three space and can be defined by a vector, rigid bodies occupy space and have geometrical properties, such as a center of mass, moments of inertia, and most importantly they can have six degrees of freedom (translation in all three axes plus rotation in three directions). The ‘explosion’ in destruction tools A scene from '2012', visual effects by Digital Domain. Another scene from 2012.