#Houdini vex add attribute update#
#Houdini vex add attribute code#
#Houdini vex add attribute plus#

On the flipside most wrangles tend to be 1 or 2 lines, 10 to 20 lines if you're getting fancy, so its not a lot of effort to debug. Error messages are arcane, syntax errors are easy to make, the help isn't alwasy helpful. That's pretty cool.Ī downside of coding, especially in something as barebones as the vex wrangle editor, is that it's pretty unforgiving when you get things wrong.

#Houdini vex add attribute update#

In most other languages you'd have to somehow iterate through all the points, create and allocate memory if it doesn't exist yet, update then probably you'd have to think up your own ways to speed it up when performance suffers, or just accept it will be slow. This gives you familiar control to the reamp VOP or fit () vex. You can map any input range to an output range. Great for shrinking the range down, up, linearizing them or cyclically repeating the attribute across it’s original range. Note that a one liner like = is pretty elegant considering what it's doing. Attribute Remap gives you complete control over your float type attributes mapping them to any range you wish. tight sine waves on red, medium cos on blue, a wide ramp on green, each driven by a different thing (position vs normal vs point number).cos waves? (wont look hugely different, cos is just sin shifted by 1/4 of a wave).x / ch ( 'scale' ) Cd = sin ( foo ) Exercises

These waves are based on If we want to drive them from each points x position, substitute for foo = P.

attributes are data that is on the geometry.

#Houdini vex add attribute code#

variables are temp throwaway data that only exists within the wrangle code.

To be more explicit about this, variables exist within the wrangle only, they never get transferred into the geometry like attributes.

These are called variables, and you define them by setting the type first (float, int, vector etc), a name, and optionally a direct assignment as we've done here. If those intermediate values are temporary, and you're unlikely to use them later on, then you can just create data that exists only within the wrangle.

#Houdini vex add attribute plus#

A lot of the time though you'll want to do some calculation first, work out this times that plus that, run through a function, adjust with a slider etc, until you finally decide to write that out to an attribute. You can both read attributes and write to them as we've done already. Things prefixed with an are attributes, data sitting on the geometry. Try the following in the point wrangle text editor, hit control-enter (or command enter on OSX) after you finish typing to make Houdini execute the code:įloat foo = float ( ptnum ) / ch ( 'scale' ) Cd = sin ( foo ) Variablesĭebated bringing this up on day 1 or wait until later, but you're a big kid, you can handle it. One of the easiest things you can do with vex is to set the colour of your geometry based on attributes. Do this, save it as your default desktop, you'll thank me later. :) A fast keyboard combo to do this is alt-] for the split, then alt-8 in the lower pane to load the geo spreadsheet. A quick way to do this is to split your viewport, then set the lower pane to be a geometry spreadsheet. As you work through these tutorials you can adjust the switch sop and transform sop to try different geometry, change the scale and rotation, see how your code works in different contexts.īeing able to see your geometry attributes is important when using vex (and for Houdini in general). V = set( m3) // Each row of the 3x3 matrix is put into a vector m3 = set( v) // Copy the vectors into the row vectors of the matrix v4 = set( m4) // Extract the rows of the matrix into the vector4 array m4 = set( v4) // Create a matrix using the vector4's in the array as row vectorsĮ.g.To save time its a hip file preconfigured with some interesting geo behind a switch node, then a transform sop, normal sop in point mode, point wrangle.