VEX

• VEX(Vector EXpressions)

  • https://www.sidefx.com/docs/houdini/ref/expression_cookbook.html
  • https://www.sidefx.com/docs/houdini/vex/lang.html
  • https://www.sidefx.com/docs/houdini/vex/functions/index.html

• jtomori/vex_tutorial

  • https://github.com/jtomori/vex_tutorial
  • https://jtomori.github.io/vex_tutorial/

• 에디터 설정

  • Edit > Preference > Set External Text Editor
  • VEXpression > 우클릭 > Expression > Edit in External Editor
  • Visual Studio Code에 VEX 플러그인

// C:\Users\ (UserName) \Documents\houdini19.0\houdini.env
EDITOR = "C:\Users\(UserName)\AppData\Local\Programs\Microsoft VS Code\Code.exe"

• 절대로 point() 또는 prim() 표현식을 사용하지 마십시오(expressions). VEX 대응만 사용하십시오.

• https://www.tokeru.com/cgwiki/?title=HoudiniVex

• https://www.sidefx.com/learn/vex/

• Attribute VOP

  • Vex 시각화 그래프

• Attribute Wrangle

  • Vex 코딩
  • Wrangle
    • This is a very powerful, low-level node that lets experts who are familiar with VEX tweak attributes using code.
    • https://english.stackexchange.com/questions/263712/what-does-come-on-lets-wrangle-up-the-cattle-mean
    • 소나 말들 관리

@P                     => points
@N                     => normals
@Cd                    => primvars:displayColor
@id                    => ids
@width,@widths,@pscale => widths
@v                     => velocities
@w                     => angularVelocities
@accel                 => accelerations
@uv                    => primvars:st
@Alpha                 => primvars:displayOpacity


v@N; // the normal. If this hasn't been set, vex will calculate it for you just by calling it without initialised values
v@up; // a vector to control the spin around the normal when using instancing/copytopoints/etc
p@orient; // vector4 used as explicit rotation for instances
3@transform; // matrix3 used to control rotation and scale for instances
4@localtransform; // matrix (4x4) used for kinefx joints
f@pscale; // uniform scale for instances
v@scale; // XYZ scale control for instances

v@P; // current elements position. can be set for points, can be read for vertices and prims. Prims will guess the midpoint, not always reliable!
v@Cd; // diffuse colour

type@attribute

• geometry sheet에서 확인 가능

i@myint         = 5;                                        // i | int

f@myfloat       = 12.234;                                   // f | float
u@myvector2     = {0.6, 0.5};                               // u | float2
v@myvector      = {1,2,3};                                  // v | float3
p@myquat        = {0,0,0,1};                                // p | float4

2@mymatrix2     = {1,2,3,4};                                // 2 | float2x2
3@mymatrix3     = {1,2,3,4,5,6,7,8,9};                      // 3 | float3x3
4@mymatrix4     = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16}; // 4 | float4x4

s@mystring      = 'a string';                               // s | string

d@mydict        = {};                                       // d | dict
d@mydict['key'] = 'value';

i[]@connected_pts = neighbours(0, @ptnum);                  // i[] | int[] array

// 정의 후 @attribute 형태로 쓸 수 있다.
// { ... } 과 set( ... ) 는 동일.

https://sites.google.com/site/fujitarium/Houdini/sop/copy-sop

// https://www.sidefx.com/docs/houdini/vex/snippets.html
vector x0 = point(0, "P", @ptnum);
vector x1 = point(1, "P", @ptnum);


float dist = distance(x0, x1);
vector dir = normalize(x1 - x0);
vector next = x0 + dir * (dist / 2.0f);

@P = next;

@

geometry attribute

• https://www.sidefx.com/docs/houdini/model/attributes.html

Expression

$BBX = relbbox(@P).x
$BBY = relbbox(@P).y
$BBZ = relbbox(@P).z

ch

• https://www.sidefx.com/docs/houdini/vex/functions/ch.html

파라미터 삭제시: More > Delete Spare Parameter

chf chi chv

Function

vector currP = @P;

// 현재 위치에서 1번 지오메트리와 맨 처음으로 마주치게될 포지션.
vector hittedP = minpos(1, currP);

// 현재 위치에서 1번 지오메트리에 있는 모든 포인트 중 가장 가까운 포인트번호.
int nearPointNumber = nearpoint(1, currP);

// 1번 지오메트리의 nearpointNumber의 _id값.
int id = point(1, "_id", nearPointNumber);

quaternion

• Quaternions
  • Math in Game Development Summit: A Visual Guide to Quaternions and Dual Quaternions

vector4 orient = quaternion(maketransform(@N, @up));
vector euler  = quaterniontoeuler(orient,XFORM_XYZ);
v@rot = degrees(euler);

// maketransform: https://www.sidefx.com/docs/houdini/vex/functions/maketransform.html

vector4  quaternion(matrix3 rotations)
vector4  quaternion(float angle, vector axis)
vector4  quaternion(vector angleaxis)

vector  qrotate(vector4 quaternion, vector v)
vector  degrees(vector nums_in_rads)
vector  quaterniontoeuler(vector4 orient, int order)

vector4  slerp(vector4 q1, vector4 q2, float bias)

vector4  qmultiply(vector4 q1, vector4 q2)

Etc

point("../OUT_P", 0, "P", 1)  // OUT_P  노드의 0번째의 point P의 Y좌표(xyz / 012)
prim("../OUT_Cd", 2, "Cd", 0) // OUT_Cd 노드의 2번째의 primitive Cd의 Red채널값(rgb / 012)
opdigits(".")                 // 현재 노드(".")의 이름의 숫자만 가져옴
rand(x)                       // 랜덤. 분포가 일정하게 되는데 그럴때 사칙연산을 내부적으로 넣어주기도 함

chramp("radious_ramp", @curveu)    // 기어버튼으로 추가된 radious_ramp curveu의 위치 값을 가져온다
detail("../META/", "iteration", 0) // META에 있는 iteration의 0번째 값



npoints(0) => 0번입력의 포인트 갯수

getpointbbox_center(input)

float xyzdist(geometry, originVector)

`opinputpath(".", 0)

@opinput‹n›_‹name› @opinput1_P // 입력 1의 P.

v@P = lerp(v@P, @opinput1_P, chf('blend'));

i@id = @ptnum // 현재 point v@P = lerp(v@P, point(1, 'P', findattribval(1, 'point', 'id', i@id)), chf('blend')); v@P = lerp(v@P, point(1, 'P', idtopoint(1, i@id)), chf('blend'));

v@pos = uvsample(0, 'P', 'uv', chv('uv'));

setdetailattrib(0, 'foo', @ptnum, 'set');

normalize cross abs dot length degree min / max sin/cos/acos

relpointbbox(2, pos); addpoint(geoself(), pos);

pointprims => point to prim

primpoints => prim to point primvertices

neighbours

pcfind 범위(radius)에서 포인트를 찾음 nearpoints // pcfind를 편히 쓸 수 있는 버전

// array insert / append removeindex removevalue push / pop resize len argsort reverse reorder find

addprim(int_geohandle, string_type) removeprim addvertex

setpointgroup setprimgroup

sprintf

pcopen pcimportbyidxf pcfilter pciterate

foreach ([element_type] value; array) {

}

foreach (index, value; array) statement;
foreach (int index; element_type value; array) statement;

int test(int a; int b; string c) { return 1; }

struct SHello { int a = 1; int b;

int Func()
{
  return a;
}

}

SHello x = SHello(1, 2);

// string startswith endswith find match concat join split lstrip / rstrip splitpath isdigit opdigits // Returns the integer value of the last sequence of digits of a string https://www.sidefx.com/docs/houdini/vex/functions/opdigits.html atoi / atof itoa

// regex string regex = r''; i@match = re_match(regex, teststring); re_match re_find re_findall re_replace re_split

https://regex101.com

https://www.sidefx.com/docs/houdini/vex/random.html