Houdini Python 快速开始

摘要

Houdini的Python耦合性比较高, 有些方法没有那么自觉.

放几个简单案例用来快速开始使用~

#coding=utf-8
import hou
#############################################
# 获取与设置节点属性
#############################################

def get_and_set_node_parameters(node_name=""):
    print("\n------------\n")
    print("Start Create!\n")
    
    current_root_node = hou.node("/obj")# type: hou.Node
    geo_node = current_root_node.createNode("geo") #type: hou.ObjNode
    if node_name:
        if not hou.node("{}/{}".format(current_root_node.path(), node_name)):
            geo_node.setName(node_name)
    geo_node.setSelected(True, clear_all_selected=True) #替换选择
    # NOTE: 在此节点下创建其它节点, 不需要选中, 以上选中仅用于测试.
    # NOTE: run_init_scripts的作用主要是在Geometry中内置一个File SOP
    #       如果设置为了False就不会做这个事情了
    #       除此以外还有一些渲染相关的参数也不会被加到Geometry中
    box_node = geo_node.createNode("box", run_init_scripts=False) # type: hou.SopNode
    box_node.moveToGoodPosition()
    # 细分节点
    subd_node = geo_node.createNode("subdivide", run_init_scripts=False)# type: hou.SopNode
    # NOTE: 设置生成节点的参数
    iteration_parm = subd_node.parm("iterations") # type: hou.Parm
    if iteration_parm:
        iteration_parm.set(3)
    subd_node.setInput(0, box_node)
    subd_node.moveToGoodPosition() # 自动设置在Houdini 中的 layout
    subd_node.setDisplayFlag(True)
    subd_node.setRenderFlag(True)
    print("\n------------\n")
    print("Sub node count under {}:{}".format(geo_node.path(), geo_node.numItems()))

    # 参数获取
    box_tx_ch = hou.ch("{}/tx".format(box_node.path()))
    print("box_tx type: {} val: {}".format(type(box_tx_ch),box_tx_ch))
    box_scale = box_node.parm("scale") #type: hou.Parm
    print("box_scale type: {} val: {}".format(type(box_scale), box_scale.eval()))
    # 复数参数
    box_divs = box_node.parmTuple("divs") # type: hou.ParmTuple
    print("box_divs type: {} val: {}".format(type(box_divs), box_divs.eval()))
    box_parms_list =box_node.parms() # type: tuple[hou.Parm]
    print("\n------------\n")
    print(box_parms_list)
    print("\n------------\n")
    box_parm_tuples = box_node.parmTuples() #type: tuple[hou.ParmTuple]
    print(box_parm_tuples)
    print("\n------------\n")
    
    # NOTE:
    # ParmTuple -> size : tuple[Parm]
    # Parm -> sizex, sizey, sizez : Parm
    
    # 参数设置
    box_node.parm("tx").set(box_tx_ch + 0.5)
    box_node.parmTuple("size").set([0.5,0.5,0.5])
    box_scale.set(2)
    box_divs.set([0,10,0])
    

    # eval 用于返回表达式值
    # houdini的设置属性，一般都是set
    # 但是如果想获取到属性值，就必须得用eval，他没有对应的get函数，这个和平常不太一样
    val_box_div_a = box_divs.eval()
    val_box_div_b = box_node.evalParmTuple("divs")
    val_geo_tx_a = geo_node.evalParm("tx")
    val_geo_tx_b = geo_node.parm("tx").eval()
    print("divs:{}, divs:{}, tx:{}, tx:{}".format(val_box_div_a, val_box_div_b, val_geo_tx_a, val_geo_tx_b))

    geo_node.moveToGoodPosition()

get_and_set_node_parameters("TestNode")


#############################################
# 从节点反向生成代码
#############################################
# ref: https://elmagnifico.tech/2023/04/21/Houdini-GeometrySpreadsheet/

def get_code_from_object ():
    
    current_root_node = hou.node("/obj")# type: hou.Node
    geo_node = current_root_node.createNode("geo") #type: hou.ObjNode
    box_node = geo_node.createNode("box", run_init_scripts=False) # type: hou.SopNode
    geo_node.setSelected(True, clear_all_selected=True)
    
    # print(hou.node("/obj/box1").asCode())
    print(box_node.asCode())