Hit the little plug icon to the right of the text editor, Houdini scans the vex code, realises you’ve referred to a channel that doesn’t exist yet, and. bookmark_tabs: A collection of code snippets and examples showing syntax and capabilities of VEX language inside SideFX Houdini – jtomori/vex_tutorial. Introduction. For those who tried (or afraid to start) to learn VEX but fail and stop because it was too hard. Here you will learn VEX and some.

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That said, certain operations are easier in vops, like using noise or loading other patterns, or building stuff when you don’t exactly know what you’re aiming for yet. I then take the output value of myrand, and connect that to my network. We’ll make concentric sine waves that radiate from the center. Returns the default name of the depth plane as it appears in the compositor preferences. I end up using loads of these all through my setups.

This is a struct representing an accumulator for Light Path Expressions. Another thing that I learned but didn’t really understand, forgot, learned again, forgot, then feared for a while, and now finally have an understanding of I think.

If we measure the length just using P. It returns the matrix for a given object, which you can then multiply your points by, or use cracktransform to just extract the information you need.

A VEX program that creates or filters channel data is written for the chop context. Houdini then compiles the node network into executable VEX code.

VEX language reference

What you can do is create a temporary quaternion which is 20 degrees around x around the origin, then qmultiply that with bex original quaternion.


For the rest of the time interval it interpolates from its current position to the target neighbour, while making the neighbour do the reverse.

Generates turbulence matching the output of the HScript turb expression function. If you’ve used a ray sop, this is a similar thing. There’s more minor changes in the hip file everything is driven by a time var ‘t’ rather than Time so I can speed things up or slow it down, and a few other thingsbut that’s the core of the effect.

Rather than set explicit rotations, we set a small houdiji of rotation, and accumulate it each frame. The full list is here: To generate randaxis, lets say we want it to randomly generate 0 1 or 2 every second.


Often I’ll start something in vops, then vvex part of my network would be much neater as a few lines of vex. Half-edges VEX has functions that let you treat edges as unshared per-face “half-edges”. Returns the set of unique values across all values for an int or string attribute.

It’s worth pointing out that if you’re defining the groups bex, you’re better off using an attribute to identify the pieces, and use that to do your random whatevers. But what if you want the colour of point 5?

HoudiniVex – cgwiki

Four floating point values. Returns an anisotropic volumetric BSDF, which can scatter light forward or backward. If we didn’t have colours on the cubes, or motion blur, we could leave this in a normal wrangle and call it done.

If the default names from your input nodes aren’t to your liking, you can drop a null in-between to give you nicer names. When using N and up for rotation, N points along the z-axis, up points along the y-axis. This implies some tricky situations. Turns out that rand vectors aren’t as random as you’d expect, they tend to all aim along positive values along the x y and z axis. Returns position derivative on a primitive at a certain parametric u, v position.


To create that temp quaternion is easier than you’d think; the quaternion function can take an angle and axis, or even lazier, define the axis vector, then scale that vector.

Returns the default name of the bump plane as it appears in the compositor preferences. Transforms a position from normal device coordinates to the coordinates in the appropriate space. Returns the default name of the luminence plane as it appears in the compositor preferences. Because pcopen hhoudini the closest 8 Cd results near the current point, pcfilter will vrx the average of those 8 points.

Jesse reminded me of another method; I mentioned earlier that to use the rotate matrix by itself won’t work because it applied rotation around the origin.

How do I iterate through the geometry? Returns the refraction ray given an houfini direction, the normalized normal and an index of refraction.

Assume we have an integer ‘randaxis’ that can be 0 1 or 2, and a vector ‘axis’:. Loops and flow control Arrays Strings Vex compiler vcc Overview of how to use the VEX language compiler vcc and its pre-processor and pragma statements.