试用 Houdini Engine Python API

本文主要是介绍试用 Houdini Engine Python API，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

介绍

hapi 这个python包是HoudiniEngine的一层python封装。

使用python的优势是灵活性，因为C代码总需要编译，使得迭代较慢。

Tips：
hapi中的内容总可以查阅HoudiniEngine的文档，因为概念和函数是相同的。

使用环境

1. Houdini编辑器内：Python Shell

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在其中可以 import hapi：

2. Houdini命令行工具：hython.exe

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启动它相当于启动python，当然Houdini同时也应该设置了必要的环境。
在其中可以导入hapi：

试用

代码来源于HAPI Cookbook : Create an Input Mesh（但做了些许改动）：

import hapi
import numpy# Create an in process HAPI session. It's also possible to
# connect to a remote session, such as a Houdini SessionSync
# session, if one is available. For example:
# session = hapi.createThriftSocketSession("localhost", 9090)
session = hapi.createInProcessSession()# Init the session with default cook options.
options = hapi.CookOptions()
hapi.initialize(session, options)# Define vertex positions for our test geometry
vertexPositions = numpy.array([-0.5, -0.5, -0.5,0.5, -0.5, -0.5,0.5, -0.5,  0.5,-0.5, -0.5,  0.5,-0.5,  0.5, -0.5,0.5,  0.5, -0.5,0.5,  0.5,  0.5,-0.5,  0.5,  0.5])# Face and vert info for our test geometry
vertexIndices = numpy.array([1,5,4,0,2,6,5,1,3,7,6,2,0,4,7,3,2,1,0,3,5,6,7,4])
faceCounts = numpy.array([4, 4, 4, 4, 4, 4])
nVerts = len(vertexPositions)//3
nFaces = len(vertexIndices)//4# Construct an input node to stash our geo into 
input_id = hapi.createInputNode(session, "input_node")
geo_info = hapi.getDisplayGeoInfo(session, input_id)# Build the the part info and store it to our geo info. This is an example
# of what access a HAPI struct in Python looks like. Python provides a 
# constructor for the struct that default-initializes all of the fields. Theh
# fields can then be accessed as properties on the object.
part_info = hapi.PartInfo()
part_info.vertexCount = len(vertexIndices)
part_info.faceCount = nFaces
part_info.pointCount = nVerts
part_info.type = hapi.partType.Meshhapi.setPartInfo(session, geo_info.nodeId, 0, part_info)# Define the attribute info for the P attribute
p_info = hapi.AttributeInfo()
p_info.exists = True
p_info.owner = hapi.attributeOwner.AttrownerPoint
p_info.count = nVerts
p_info.tupleSize = 3
p_info.storage = hapi.storageType.Float
p_info.originalOwner = hapi.attributeOwner.AttrownerInvalid# P attribute can then be added to the geo
hapi.addAttribute(session, geo_info.nodeId, 0, "P", p_info)# We still need to tell HAPI how many values to extract from the input array.
# HAPI is able to use less than the total number of values.
hapi.setAttributeFloatData_np(session, geo_info.nodeId, 0, "P", p_info,vertexPositions, 0, nVerts)# Set the face and vert info on the geo itself.
hapi.setFaceCounts_np(session, geo_info.nodeId, 0, faceCounts, 0,len(faceCounts))
hapi.setVertexList_np(session, geo_info.nodeId, 0, vertexIndices, 0,len(vertexIndices))# Submit all of the geometry changes we've made so they're added to Houdini.
hapi.commitGeo(session, geo_info.nodeId)# We can then ask the node to save it's geometry to disk.
hapi.saveGeoToFile(session, geo_info.nodeId, '/tmp/hapi_createmesh.bgeo.sc')