Houdini FX

• POPs
• Python
• Fun Shelf Scripts
• PythonModule Scripts
• Move Files
• split by group
• Update frame range from file
• OnCreated scripts
• Bake Camera from Alembic
• Get frame range from alembic
• Example On Node Buttons
• Send to Tops
• Set Frame Range without Script
• ROP
• Pull version from hipname
• Get Frame Size of Image File
• Create Agent from built in mocap rig - Simple
• Send selected nodes to new object (fancy way to create object merges)
• Send nodes to new alembic export
• TOPs - symlink output file of parent
• Copy Text to Clipboard example
• VEX
• Camera Stuff
• Points
• If then statements
• Transforms and Junk
• Orientation
• Spiral
• Links
• Expressions

POPs

Random Spin:

// The following makes it random:
axis = rand(@id) - set(0.5, 0.5, 0.5);
spinspeed *= rand(@id+0.1);

Python

Fun Shelf Scripts

Version up sops that have a "version" parm - I use this to version up a lot of exports in tops or rops:

import hou
nodes = hou.selectedNodes()
for x in nodes:
	ver = x.parm("version").eval() + 1
	x.parm("version").set(ver)

Send a ROP fetch to TOPs name "topnet1" for convenient cooking.:

import hou
nodes = hou.selectedNodes()
topnet = hou.node("/obj/topnet1")
frb = round((hou.playbar.frameRange()[1] - hou.playbar.frameRange()[0]) / 2)

if not topnet:
    topnet = hou.node("/obj").createNode("topnet")
    topnet.setName("topnet1")
if not hou.node("/obj/topnet1/rangegenerate_start"):
    rg = topnet.createNode("rangegenerate")
    rg.setName("rangegenerate_start")
for x in nodes:
    ver = x.parm("ver")
    path = x.path()
    name = x.name()
    if x.parm("extra"):
        name = name + x.parm("extra").eval()
    else: pass
    topcache = topnet.createNode("ropfetch")
    p = hou.IntParmTemplate("version", "Version", 1)
    g = topcache.parmTemplateGroup()
    g.append(p)
    topcache.setParmTemplateGroup(g)
    topcache.parm("version").set(ver)
    topcache.parm("roppath").set(path)
    topcache.parm("framesperbatch").set(frb)
    topcache.setName(name)

Send SOP to a ROP net named "ropnet1", adds version parm to update the original SOP version cache: 

import hou
nodes = hou.selectedNodes()
ropnet = hou.node("/obj/ropnet1")
for x in nodes:
    name = x.name()+"_"+str(x.parent())
    path= x.path()
    if x.type().name() == "rop_geometry":
        ver = x.parm("vp_version")
    elif x.type().name() == "rop_alembic":
        ver = x.parm("vp_version")
    else:
        ver = x.parm("version")
    topcache = ropnet.createNode("fetch")
    topcache.parm("source").set(path)
    p = hou.IntParmTemplate("version", "Version", 1)
    g = topcache.parmTemplateGroup()
    g.append(p)
    topcache.setParmTemplateGroup(g)
    topcache.parm("version").set(ver)
    topcache.setName(name)

Make a file node from a rop export node:

import hou, re
nodes = hou.selectedNodes()
parent = nodes[0].parent()
nodeList = []
for x in nodes:
    name = x.name()+"_load"
    
    version = x.parm("vp_version").eval()
    path= x.parm("sopoutput").eval()
    path = str(path)
    newpath1 = re.sub("_v\d+", "_v{0}", path).format("`padzero(3,ch('version'))`")
    newpath1 = re.sub("\.\d+", ".$F4", newpath1)
    
    
    file = parent.createNode("file")
    try:
        file.setName(name)
    except:
        continue
    file.setColor(hou.Color(0,0,1))
    file.parm("file").set(newpath1)
    p = hou.IntParmTemplate("version", "Version", 1)
    g = file.parmTemplateGroup()
    g.append(p)
    file.setParmTemplateGroup(g)
    file.parm("version").set(version)
    nodeList.append(file)
    
parent.layoutChildren(items=nodeList)

Open Directory from Tops

import hou, re
nodes = hou.selectedNodes()

for x in nodes:
    rpath = x.parm("roppath").eval()
    tnode = rpath.rpartition("/")[0]
    dirpath = hou.node(tnode).parm("file").eval()
    dirpath = dirpath.rpartition("/")[0]
    hou.ui.showInFileBrowser(str(dirpath))
    

Get Alembic camera, import it, and link to other nodes:

import hou, os

#set parent network
network = hou.node("/obj")

#get shot number and cache directory
shot = os.getenv("SHOT")
shotcam = shot.split("/")[-1] +"_cam"
cache = os.getenv("CACHE") + "/layout/cam"


#get alembic file
getcampath = hou.ui.selectFile(cache, "SelectCamera", pattern="*.abc")
getcampath = hou.expandString(getcampath)

#make alembic node, set name, connect to SCALE node and add to CAMERA NODE
alnode = network.createNode("alembicarchive", shotcam)
alnode.parm("fileName").set(getcampath)
alnode.parm("buildHierarchy").pressButton()
alnode.setInput(0, hou.node("/obj/SCALE"))
hou.node("/obj/CAMERA").parm("CAMERA").set(f"/obj/{alnode}/CAM/CAMShape")

 

PythonModule Scripts

Get houdini version:

hver = hou.applicationVersionString().rpartition('.')[0]

Move Files

import os,hou, shutil
selected = hou.selectedNodes()
for x in selected:
    if x.parm("env_map"):
        file = x.parm("env_map").eval()
        parm1 = x.parm("env_map")
    elif x.parm("fileName"):
        file = x.parm("fileName").eval()
        parm1 = x.parm("fileName")
    else:
        pass
    filename = os.path.basename(file)
    destdir = os.path.join(hou.expandString("$HIP"), "assets")
    destpath = os.path.join(destdir, filename)
    if os.path.exists(file):
        if os.path.exists(destdir):
            pass
        else:
            os.makedirs(destdir)
                
        if os.path.exists(destpath):
            dpath = os.path.join(os.path.join("$HIP", "assets"), filename)
            parm1.set(dpath)
        else:
            shutil.copy(file, destdir)
            dpath = os.path.join(os.path.join("$HIP", "assets"), filename)
            parm1.set(dpath)
            
    else:import os,hou, shutil
selected = hou.selectedNodes()
for x in selected:
    if x.parm("env_map"):
        file = x.parm("env_map").eval()
        parm1 = x.parm("env_map")
    elif x.parm("fileName"):
        file = x.parm("fileName").eval()
        parm1 = x.parm("fileName")
    else:
        pass
    filename = os.path.basename(file)
    destdir = os.path.join(hou.expandString("$HIP"), "assets")
    destpath = os.path.join(destdir, filename)
    if os.path.exists(file):
        if os.path.exists(destdir):
            pass
        else:
            os.makedirs(destdir)
                
        if os.path.exists(destpath):
            dpath = os.path.join(os.path.join("$HIP", "assets"), filename)
            parm1.set(dpath)
        else:
            shutil.copy(file, destdir)
            dpath = os.path.join(os.path.join("$HIP", "assets"), filename)
            parm1.set(dpath)
            
    else:
        pass
        pass

split by group

import hou
selected = hou.selectedNodes()[0]
groups = [g.name() for g in selected.geometry().primGroups()]
for i, name in enumerate(groups, 1):
        #make a split node
        split = selected.createOutputNode("blast")
        split.setName(name)
        split.parm("group").set(name)
        split.parm("negate").set(1)
        split.moveToGoodPosition()




for node in selected:
        out = node.createOutputNode("null")
        out.setName("OUT_"+node)
        out.moveToGoodPosition()

Update frame range from file

def grabFrames(self):
    import os
    plate = self.parm("backplate").eval()
    if not plate:
        framex = self.parm("frange1").eval()
        framey = self.parm("frange2").eval()
    else:
        flist = [x.split(".")[-2] for x in os.listdir(os.path.dirname(plate))]
        fmin = min(flist)
        fmax = max(flist)
        self.parm("frange1").set(int(fmin))
        self.parm("frange2").set(fmax)
        framex = self.parm("frange1").eval()
        framey = self.parm("frange2").eval()
    
    hou.playbar.setFrameRange(framex, framey)
    hou.playbar.setPlaybackRange(framex, framey)
    

OnCreated scripts

OnCreated Script to set name, color, shape of node:

cachename = hou.ui.readInput("Enter cache name")
node = kwargs["node"]
node.setName(cachename[1])
node.setUserData('nodeshape', "tilted")
node.setColor(hou.Color(1,0,0))

Bake Camera from Alembic

import hou
obj = hou.node("/obj")

ocam = hou.node(hou.ui.selectNode(node_type_filter=hou.nodeTypeFilter.ObjCamera))

reslist = ["1920x1080", "3840x2160", "3072x2109", "2224x1548", "Keep Original", "Custom"]
sl = hou.ui.selectFromList(reslist, message="choose resolution", sort=True, exclusive=True)
stopval = sl[0]
resolution = reslist[stopval]
if resolution is "Keep Original":
pass
elif resolution is "Custom":
custom = hou.ui.readInput("Enter resolution as #x# format, ie: 1920x1080. The x is needed.", title="Enter Resolution")
resolution = custom[1]
ocam.parm("resx").set(resolution.split("x")[0])
ocam.parm("resy").set(resolution.split("x")[1])

else:
ocam.parm("resx").set(resolution.split("x")[0])
ocam.parm("resy").set(resolution.split("x")[1])

try:
shotinfo = hou.node("/obj/SHOTINFO")
backplate = shotinfo.parm("backplate")
except:
backplate = " "
pass

camName = ocam.name() + "_baked"
#setback = ocam.parm("vm_background").set(backplate)
tcam = obj.createNode("cam", camName)
tcam.moveToGoodPosition()

#copy keyframes
cam_xform=["tx", "ty", "tz", "rx", "ry", "rz"]
cam_parms=["resx", "resy", "aspect", "focal", "aperture", "orthowidth", "shutter", "focus", "fstop"]
tcam.parm("vm_background").set(backplate)

parms_bake = list()
parms_bake.extend(cam_xform)
parms_bake.extend(cam_parms)
start = hou.playbar.playbackRange()[0]
end = hou.playbar.playbackRange()[1]

with hou.undos.group("bake cam"):
for x in range(int(start), int(end +1)):
hou.setFrame(x)
tcam.setWorldTransform(ocam.worldTransform())
for p in parms_bake:
parm = tcam.parm(p)
if parm.name() in cam_xform:
parm.setKeyframe(hou.Keyframe(parm.eval()))
else:
parm.setKeyframe(hou.Keyframe(ocam.parm(p).eval()))

Get frame range from alembic

This script should be added to a button on a node (thats why it's funnyily formated)

 

import _alembic_hom_extensions as ahe; import hou; anode = hou.pwd(); cam = anode.parm("camera").eval(); fpath = hou.node(cam).parm("fileName"); ver = fpath.eval().split("_")[-1].split("/")[0]; print(ver); name = hou.node(cam).children() ; print(name[0]); anode.parm("cameraVer").set(ver); name = str(name[0]); anode.parm("cameraName").set(name); alembicpath= fpath.eval(); timerange = ahe.alembicTimeRange(alembicpath); start_time=timerange[0]*hou.fps(); end_time = timerange[1]*hou.fps(); anode.setParms({"framemin":start_time, "framemax":end_time}) 

Example On Node Buttons

This is how a button on a non-adminned node needs to be laid out:

import hou (probably not needed) ; do something ; 

This grabs frame range from supplied alembic camera, updates names, etc:

import _alembic_hom_extensions as ahe; import hou; anode = hou.pwd(); cam = anode.parm("camera").eval(); fpath = hou.node(cam).parm("fileName"); ver = fpath.eval().split("_")[-1].split("/")[0]; print(ver); name = hou.node(cam).children() ; print(name[0]); anode.parm("cameraVer").set(ver); name = str(name[0]); anode.parm("cameraName").set(name); alembicpath= fpath.eval(); timerange = ahe.alembicTimeRange(alembicpath); start_time=timerange[0]*hou.fps(); end_time = timerange[1]*hou.fps(); anode.setParms({"framemin":start_time, "framemax":end_time}) 

This sets frame range from ranges on node:

import hou; anode = hou.pwd(); start = anode.parm("framemin").eval(); end = anode.parm("framemax").eval(); hou.playbar.setFrameRange(start, end); hou.playbar.setPlaybackRange(start, end)

This grabs info from animation alembic:

import hou; anode = hou.pwd(); anim = anode.parm("anim").eval(); fpath = hou.node(anim).parm("fileName"); ver = fpath.eval().split("_")[-1].split("/")[0]; name = hou.node(anim) ; anode.parm("animVer").set(ver); name = str(name); anode.parm("animName").set(name); 

oneliner for-loop -- updates name by index (not complete, need inputs):

i = 0; [cn.parm("name" + str(i := i + 1)).set(x.split("/")[-1]) for x in nodes]

Send to Tops

import hou
nodes = hou.selectedNodes()
topnet = hou.node("/obj/topnet1")
if not topnet:
    topnet = hou.node("/obj").createNode("topnet")
    topnet.setName("topnet1")
for x in nodes:
    name = x.name()+"_"+str(x.parent())
    fstart = x.parm("f1").eval()
    fend = x.parm("f2").eval()
    if x.type().name() == "rop_geometry":
        ver = x.parm("vp_version")
        path = x.path()
    elif x.type().name() == "rop_alembic":
        ver = x.parm("vp_version")
        path = x.path()
    elif x.type().name() == "filecache::2.0":
        path= x.path() + "/render"
        ver = x.parm("vp_version")
    else:
        ver = x.parm("version")
        path = x.path()
        
    topcache = topnet.createNode("ropfetch")
    try:
        if x.parm("cachesim").eval() is 1:
            topcache.parm("batchall").set(1)
            topcache.setColor(hou.Color(.5,0,0))
        else:
            topcache.parm("framesperbatch").set(15)
            topcache.setColor(hou.Color(0,.5,0))
    except:
        if x.parm("initsim").eval() is 1:
            topcache.parm("batchall").set(1)
            topcache.setColor(hou.Color(.5,0,0))
        else:
            topcache.parm("framesperbatch").set(15)
            topcache.setColor(hou.Color(0,.5,0))
    p = hou.IntParmTemplate("version", "Version", 1, min=1, max=40)
    g = topcache.parmTemplateGroup()
    g.insertAfter("pdg_servicename", p)
    topcache.setParmTemplateGroup(g)
    topcache.parm("version").set(ver)
    topcache.parm("roppath").set(path)
    topcache.setName(name)

Set Frame Range without Script

 

import hou; anode = hou.pwd(); start = anode.parm("framemin").eval(); end = anode.parm("framemax").eval(); hou.playbar.setFrameRange(start, end); hou.playbar.setPlaybackRange(start, end)

ROP

PostRender open MPLAY:

import os; img_path = "`chs("picture")`".replace("$F", "\*"); os.system("mplay %s" % img_path)

Pull version from hipname

Can be used in a parameter. Returns a integer.

import hou, re
version = re.findall('_v\d+', hou.hipFile.basename())[0]
version = int(re.findall('\d+', version)[0])
return version

Get Frame Size of Image File

node= hou.pwd(); bg=node.parm("image").eval(); res=hou.imageResolution(bg); node.parm("framesizex").set(res[0]); node.parm("framesizey").set(res[1]);

Create Agent from built in mocap rig - Simple

This will take a test mocap rig 3 built in to houdini, create an agent, add agent clips from the built in library (must be in your scene already), and lay everything out. 

import hou
obj = hou.node("/obj")
agentname = hou.ui.readInput("Agent Name", title="Name")
agentname =  agentname[1]

agentpNode = obj.createNode("geo")
agentNode = agentpNode.createNode("agent")

agentpNode.setName(agentname)
agentNode.setName(agentname)
agentnet = agentpNode

inputMoc = hou.ui.selectNode(title="Select Character Rig to base agent on", multiple_select=False, node_type_filter=hou.nodeTypeFilter.ObjSubnet)


agentNode.parm("agentname").set(agentname)
agentNode.parm("objsubnet").set(inputMoc)


#clips = hou.ui.selectNode(multiple_select=True, node_type_filter=hou.nodeTypeFilter.Obj)
clips = hou.ui.selectNode(title="Select all clips - mocap biped 3 rigs", multiple_select=True, node_type_filter=hou.nodeTypeFilter.ObjSubnet)
agentclip = agentnet.createNode("agentclip")
clipprops = agentnet.createNode("agentclipproperties")


clipnum = len(clips)
clipcount = 1

agentclip.parm("locomotionnode").set("Hips")


#print(clipnum)
for x in clips:
    node = hou.node(x)
    name = node.name()
    path = str(x)
    nframes = node.parm("nFrames")
    fs =hou.playbar.timelineRange()[0]
    fe = int(fs) + int(nframes.eval())
    agentclip.parm("framerange" + str(clipcount) +"_1").deleteAllKeyframes()
    agentclip.parm("framerange" + str(clipcount) +"_2").deleteAllKeyframes()
    agentclip.parm("clips").set(clipnum)
    agentclip.parm("name" + str(clipcount)).set(name)
    agentclip.parm("objsubnet" + str(clipcount)).set(path)
    agentclip.parm("framerange" + str(clipcount) +"_1").set(fs)
    agentclip.parm("framerange" + str(clipcount) +"_2").set(fe)
    agentclip.parm("converttoinplace" + str(clipcount)).set(True)
    
    clipprops.parm("numclips").set(clipnum)
    clipprops.parm("clipname_" + str(clipcount)).set(name)
    clipprops.parm("enableblending_" + str(clipcount)).set(True)
    clipprops.parm("framesbefore_" + str(clipcount)).set("5")
    clipprops.parm("framesafter_" + str(clipcount)).set("5") 
    
   
    
    
    
    clipcount = clipcount+1

agentclip.setFirstInput(agentNode)
clipprops.setFirstInput(agentclip)
agentpNode.layoutChildren()

Send selected nodes to new object (fancy way to create object merges)

import hou
nodes = hou.selectedNodes()
destnode = hou.node(hou.ui.selectNode(title="select destination node"))
for x in nodes:
    name = x.name()+"_"+str(x.parent())
    path= x.path()
    objmergenode = destnode.createNode("object_merge")
    objmergenode.parm("objpath1").set(path)

    objmergenode.setName(name)
    objmergenode.setColor(hou.Color(0,1,0))
    

Send nodes to new alembic export

import hou
nodes = hou.selectedNodes()
destnode = hou.node("/obj/EXPORT")
if not destnode:
    destnode = hou.node("/obj").createNode("geo")
    destnode.setName("EXPORTS")
    
for x in nodes:
    name = x.name()+"_"+str(x.parent())
    path= x.path()
    objmergenode = destnode.createNode("object_merge")
    objmergenode.parm("objpath1").set(path)

    objmergenode.setName(name)
    objmergenode.setColor(hou.Color(0,1,0))
    
    alembicrop = destnode.createNode("rop_alembic")
    alembicrop.setName(str(x.parent()))
    alembicrop.parm("trange").set(1)
    alembicrop.parm("f1").deleteAllKeyframes()
    alembicrop.parm("f1").set(int("1001"))
    alembicrop.parm("build_from_path").set(1)
    alembicrop.setInput(0, objmergenode)
    destnode.layoutChildren()
    

 

TOPs - symlink output file of parent

 

exportFile = str(work_item.expectedInputFiles[0])
dir = os.path.dirname(exportFile)
newFile = os.path.join(dir, "cache.abc")

os.symlink(exportFile, newFile)

Copy Text to Clipboard example

This example I make a dictionary and copy to clipboard. I also gather a frame range from files on disk. 

#needed: name, path, start, end
import hou, os
from pathlib import Path

def getinfo():
    pathname = hou.ui.selectFile(collapse_sequences=True)
    filename = Path(pathname.split(".")[0])
    parent = filename.parent
    
    #get frame range
    filenames = [file.name.split(".")[-2] for file in parent.iterdir() if file.is_file()]
    start = min(int(i) for i in filenames)
    end = max(int(i) for i in filenames)
    
    #reformatting stuff
    name = str(filename).split("/")[-1]
    path = str(filename)+"."

    return name, path, start, end

    
def wrangle():
    wranglenode = hou.selectedNodes[0]
#assign variables to function so we can use them globally
name, path, start, end = getinfo()

#format stuff
q = '"'
textForWrangle = f'dict {name}; \n {name}[\'name\'] = {q}{name}{q}; \n {name}[\'path\'] = {q}{path}{q}; \n {name}[\'startFrame\'] = {start}; \n {name}[\'endFrame\'] = {end}; \n append(chars,{name}); '
print(textForWrangle)
#copy to clipboard
hou.ui.copyTextToClipboard(textForWrangle)

hou.ui.displayMessage(title="Copied", text=f"Here is what was copied to clipboard: {textForWrangle} \n")

 

VEX

Camera Stuff

auto focus, get distance from object and camera:

vlength(vtorigin(“/obj/geo1”, “/obj/cam1”))

Points

divide points into 3 equal parts:

i@part = floor(fit(rand(@ptnum+.258), 0, 1, 0, 2.9));

 

point normal to center:

 

If then statements

If the pscale is greater than .4 then set it to .2, if not set it to its current pscale

@pscale = @pscale>.4?.2:@pscale

 

 

Transforms and Junk

1. transforms to attribute matrix:

p@orient = quaternion(3@transform);
v@scale = cracktransform(0,0,2,set(0.0.0). 3@transform);

2. rotate packed fracture based on point + distance:

vector p1= set(@P.x, @P.y, @P.z);

vector crack1 = point(1, "P", 0);
vector crack2 = point(2, "P", 0);
vector p2 = crack1-p1;
vector p3 = crack2-p1;
float n = fit ( length ( p2 ), 0, ch("maxdist"), ch('mult'), 0 );
float n2 =  fit ( length ( p3 ), 0, ch("maxdist2"), ch('mult2'), 0 );

vector4 q0 = quaternion ( 0 );
vector4 q1 = sample_orientation_uniform ( rand ( @ptnum ) );
vector4 q2 = slerp ( q0, q1, n+n2 );
matrix3 xform = qconvert ( q2 );

setprimintrinsic ( 0, "transform", @ptnum, xform );

3. Blending spiral (end beg):

vector target = point(1, "P", @ptnum);
float blend = chramp("blendAlongSpiral", @curveu)*chf("multiplier");

@P = lerp(@P, target, blend);

4. Position copy via uv:

v@P = uvsample(1, "P", "uv", @P);

5. move near points together:

int near = nearpoint(1, @P);
vector target = point(1, "P", near);
@P = target;

 

Orientation

Get transform and orientation from camera:

string camera = "/obj/alembicarchive1/Camera2/CameraShape2"; // path to your camera
@P = ptransform(camera, "space:current", {0,0,0});
@N = ntransform(camera, "space:current", {0,0,-1});

 

Spiral

#include "math.h"
#include "voplib.h"

float easeOutCirc ( float t )
{
    return sqrt ( 1 - ( pow ( ( 1 - t ), 2 ) ) );
}

float index = @ptnum;
float numpts = @numpt;
float startAngle = radians ( ch("angle") );
float dir = 2 * ch("dir") - 1;
float steps = ( numpts - 1 ) / ch("turns");
float stepAngle = ( 2 * PI / steps ) * dir;

float inc = index / ( numpts - 1 );
int mirror = chi("spherical");
float linear = ( 1 + mirror ) * inc;
if ( mirror && index + 1 > numpts / 2 )
    linear = ( 1 + mirror ) * ( 1 - inc );

float circ = easeOutCirc ( linear );
float interp = linear + ( circ - linear ) * ch("roundness");
float r = ( ch("rx") + interp * ( ch("ry") - ch("rx") ) );

//  Apply power to radius at the end (after curvature)
inc = ( ( numpts - 1 ) - index ) / ( numpts - 1 );
float theta = 2 * PI * inc;
if ( mirror && index + 1 > numpts / 2 )
    theta = 2 * PI * ( 1 - inc );
r *= pow ( ch("falloff"), theta );

float angle = index * stepAngle + startAngle;
float x = sin ( angle ) * r;
float z = cos ( angle ) * r;
float h = index / ( numpts - 1 );
float y = vop_bias ( h, 0.5 * ch("bias") + 0.5 );
y = vop_gain ( y, 0.5 * ch("gain") + 0.5 ) * ch("height");

matrix3 xform = dihedral ( { 0, 1, 0 }, { 0, 0, -1 } ) * lookat ( 0, normalize ( chv("n") ) );
@P = ch("scale") * set ( x, y, z ) * xform + chv("t");

 

Links

Big resource:

https://lex.ikoon.cz/vex-snippets/

Expressions

Switch by Normal:

if(point("../resample3", 0, "N", 2)<0, 0, 1)