Houdini_intro

Roll Tube - Attributes / Geometry / UV

Base

Scatter
copytopoints
Group -> group the bottom point

PolyLine

Bezier -> PolyLine

Resample

Mesh

add noise in pscale and p

Attributes

https://entagma.com/courses/ahtya-2-adding-houdini-to-your-arsenal-2-0/ahtya-2-0-pt-08-understanding-attributes-in-houdini/

Unlike groups, attribs allow us to specify a data type. In this case we’re using a float attrib (a number with a decimal point) to create a smooth

P - Positions (Vector	Points)
N - Normals / Directions (Vector	Points or Vertices)
uv - UV Coordinates (Vector	Points or Vertices)
Cd - Color (Vector	Points)
pscale - Scaling / Size of stuff (Float	Points)

maskbyfeature
timeshift -> become static 解决让某一部分不按frame变化 (remove attribute animation)
Output
remove extra output, clear attribute -> which can be clear in the shader

Geometry

edge: not for building the model, but for selection
vertices has direction

When working with groups and attribs, using points or prims is usually a lot simpler and more practical, than using vertices.

However in some cases, for instance in normals or uvs, vertices do offer us more options, we might need to get the desired result.

UV

For Loop

https://entagma.com/courses/ahtya-2-adding-houdini-to-your-arsenal-2-0/ahtya-2-0-pt-13-understanding-for-loops-in-houdini/

Foreach loop
- piece (name)
- point
- primitive
- feedback(add randomness to each element)
clip
blast
matchsize

switch
- selection input(bool) eg. rand(detail(0, "iteration", 0))>.75

Procedural city - Node / VOPs / Wrangle

import 2D OSM data to bego format

get data from OpenStreetMap
osm_import & osm_filter

Setting random height

give random height according to a base
measure (area base)

more noise
- attribrenoisse
- attribrandom
Remap -> make some different on certain building

VOPs

Bind -> import attributes

Remap

noise

index of the current primitives -> random

Wrangle / Vex

  
//Get Attrib
float area = f@area;

//Remap
float zscale = fit(area, 1.0, 25000.0, 0.0, 1.0);
zscale = chramp("Remap", zscale);
zscale = fit(zscale, 0.0, 1.0, 10.0, 30.0);

//Noise
float noise = noise(v@P/1000);
noise = chramp("Noise", noise);
noise = noise * 100;
zscale = zscale + noise;

//Random
float random = rand(i@primnum);
random = fit(random, 0.0, 1.0, 0.8, 1.2);
zscale = zscale * random;

//Update Attrib
f@zscale = zscale;

Data Visualization

import CSV -> tableimport -> Get Arrtibutes

degree -> cartesian coordinate

  
//Load in lat lon attribs and convert them to radians.
float lat = radians(f@lat);
float lon = radians(f@lon);

//Calculate xyz coordinates based on lat lon
float x = cos(lat) * cos(lon);
float y = cos(lat) * sin(lon);
float z = sin(lat);

//Write coordinates back to position and normal
v@P = set(x,y,z);
v@N = set(x,y,z);