#Houdini renderman tutorial code#

radians() - convert a number from degrees to radians: foo = radians(90).

Usually feed it the point id, so each point gets a random number: foo = sin(), cos() - as you'd expect, but in radians.

rand() - generate a random number between 0 and 1.

fit() - take a number between 2 values, fit it between 2 other values, usually 0-1.

Then I'll hit the plug button, edit the parameter interface, shift-select all the channels I made, and change the type field to 'color', and to be extra saucy, change 'show color as' to 'hsv sliders'. V colour1 = chv ( 'col1' ) v colour2 = chv ( 'col2' ) v colour3 = chv ( 'col3' ) v colour4 = chv ( 'col4' ) This affects how you might approach certain problems, which I'll come back to later. You don't have to sweat the details (for now), just understand that's what's going on.

#Houdini renderman tutorial code#

When you have lots of points, Vex runs that same code on all the points in parallel, substituting the values for Cd and P for each point automatically. You can think of the code we've done so far as working on a single point, so something = setting the colour of a point based on its position. The answer is that Vex is implicitly working in parallel. If you've used other programming languages, you might be thinking 'Ok, but how does Vex know which point to process? How do I iterate through the geometry? There's too much voodoo here!' I always forget to do this, shout at my wrangles for a bit, then finally remember to stick 'v' in front of my attribute names. BAD Cd = mycolour // This will treat it as a float and only read the first value (ie, just the red channel of // GOOD Cd = v mycolour // Explicitly tells the wrangle that its a vector. You want to define a new point float attribute 'foo'? Just type

46 Distort colour with noise and primuv.

43 Linear vertex or find the starting point on every curve.

35 xyzdist to get info about the closest prim to a position.

34 Generate a disk of vectors perpendicular to a vector.

32 Remove points that don't have normals directly along an axis.

30 Copies to sit on a surface, with random rotation, with orient.

29 Convert N and Up to Orient with maketransform.

27 More on rotation: Orient, Quaternions, Matricies, Offsets, stuff.

26 optransform to do a motion control style camera.

25 Get transform of objects with optransform.

24 Solver and wrangle for branching structures.

23 Solver sop and wrangles for simulation.

21 Access group names procedurally in vex.

17.1 That's hard to read, summarise please.16 Blurring attributes with vex and point clouds.15 Get values from other points, other geo.13 Wrangles vs hscript vs vops vs everything else.12.6 Rotate prims around an edge, alternate version.12.1 Rotate a single point with sin and cos.9 Example: Random delete points by threshold.