Houdini Engine是Houdini的一个无图形界面简化版，可以通过houdini engine与houdini内核交互，完成houdini fx中的操作。官方有For Maya, For Max, For Unity, For Unreal四个插件，可以在这四个host程序中调用houdini engine。这是极好的，意味着开发的HDA资源可以直接应用在host程序中。
不过笔者并不满足于此，是否可以不用host环境直接调用houdini engine？当然可以，官方提供了一套C API . 只不过笔者看着它就头疼，主要两个问题
- 面向过程，不面向对象
- 语法繁琐
这也是笔者开发pyhapi的初衷，希望面向对象，简化语法。
文档请见 https://pyhapi.readthedocs.io
如何安装
已经发布到PyPI，安装直接使用pip即可
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pip install pyhapi |
要求
- py>3.6, 因为用了asyncio异步库
- numpy>1.15
- Houdini17.5测试没问题，需要commercial license. Houdini18尚未测试
当然要注意的是，请确保houdini dll路径在PATH中
使用
目前支持的功能:
- 实例化节点，HDA
- 节点连接操作
- 节点参数设置
- 节点异步cook
- 传入/出 曲线，模型
还不支持的：
- 传入/出 体素
- PDG
举例来说，如果想实例化一个HDA，传入参数，cook，可以这样：
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# -*- coding: utf-8 -*- """Example of getting/setting params of HDA asset Author : Maajor Email : hello_myd@126.com """ import pyhapi as ph def main(): session = ph.HSessionManager.get_or_create_default_session() #load hda asset and instantiate hda_asset = ph.HAsset(session, "hda/SideFX_spaceship.otl") asset_node = hda_asset.instantiate(node_name="Spaceship") #Set node's parameters asset_node.set_param_value("seed", 1.0) asset_node.set_param_value("rop_geometry1_sopoutput", "$HIP/spaceship.obj") #Press button asset_node.press_button("rop_geometry1_execute", status_report_interval=1.0) session.save_hip("spaceship.hip") if __name__ == "__main__": main() |
执行完以后就可以输出spaceship.obj模型啦
对比一下C API的官方案例Parameters.c两百多行其实就干了一件事：实例化一个HDA，打印出它所有参数
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#include <HAPI/HAPI.h> #include <iostream> #include <string> #define ENSURE_SUCCESS( result ) \ if ( (result) != HAPI_RESULT_SUCCESS ) \ { \ std::cout << "Failure at " << __FILE__ << ": " << __LINE__ << std::endl; \ std::cout << getLastError() << std::endl; \ exit( 1 ); \ } #define ENSURE_COOK_SUCCESS( result ) \ if ( (result) != HAPI_RESULT_SUCCESS ) \ { \ std::cout << "Failure at " << __FILE__ << ": " << __LINE__ << std::endl; \ std::cout << getLastCookError() << std::endl; \ exit( 1 ); \ } static std::string getLastError(); static std::string getLastCookError(); static std::string getString( HAPI_StringHandle stringHandle ); int main( int argc, char ** argv ) { const char * hdaFile = argc == 2 ? argv[ 1 ] : "examples/SideFX_spaceship.otl"; HAPI_CookOptions cookOptions = HAPI_CookOptions_Create(); HAPI_Session session; HAPI_CreateInProcessSession( &session ); ENSURE_SUCCESS( HAPI_Initialize( &session, &cookOptions, true, -1, nullptr, nullptr, nullptr, nullptr, nullptr ) ); HAPI_AssetLibraryId assetLibId; ENSURE_SUCCESS( HAPI_LoadAssetLibraryFromFile( &session, hdaFile, true, &assetLibId ) ); int assetCount; ENSURE_SUCCESS( HAPI_GetAvailableAssetCount( &session, assetLibId, &assetCount ) ); if (assetCount > 1) { std::cout << "Should only be loading 1 asset here" << std::endl; exit ( 1 ); } HAPI_StringHandle assetSh; ENSURE_SUCCESS( HAPI_GetAvailableAssets( &session, assetLibId, &assetSh, assetCount ) ); std::string assetName = getString( assetSh ); HAPI_NodeId nodeId; ENSURE_SUCCESS( HAPI_CreateNode( &session, -1, assetName.c_str(), "AnAsset", false, &nodeId ) ); ENSURE_SUCCESS( HAPI_CookNode( &session, nodeId, &cookOptions ) ); int cookStatus; HAPI_Result cookResult; do { cookResult = HAPI_GetStatus( &session, HAPI_STATUS_COOK_STATE, &cookStatus ); } while (cookStatus > HAPI_STATE_MAX_READY_STATE && cookResult == HAPI_RESULT_SUCCESS); ENSURE_SUCCESS( cookResult ); ENSURE_COOK_SUCCESS( cookStatus ); HAPI_NodeInfo nodeInfo; ENSURE_SUCCESS( HAPI_GetNodeInfo( &session, nodeId, &nodeInfo ) ); HAPI_ParmInfo * parmInfos = new HAPI_ParmInfo[ nodeInfo.parmCount ]; ENSURE_SUCCESS( HAPI_GetParameters( &session, nodeId, parmInfos, 0, nodeInfo.parmCount ) ); // Print parameter info std::cout << "Parameters: " << std::endl; for( int i = 0; i < nodeInfo.parmCount; ++i ) { std::cout << "==========" << std::endl; std::cout << " Name: " << getString( parmInfos[ i ].nameSH ) << std::endl; std::cout << " Values: ("; if ( HAPI_ParmInfo_IsInt( &parmInfos[ i ] ) ) { int parmIntCount = HAPI_ParmInfo_GetIntValueCount( &parmInfos[ i ] ); int * parmIntValues = new int[ parmIntCount ]; ENSURE_SUCCESS( HAPI_GetParmIntValues( &session, nodeId, parmIntValues, parmInfos[ i ].intValuesIndex, parmIntCount ) ); for ( int v = 0; v < parmIntCount; ++v ) { if ( v != 0 ) std::cout << ", "; std::cout << parmIntValues[ v ]; } delete [] parmIntValues; } else if ( HAPI_ParmInfo_IsFloat( &parmInfos[ i ] ) ) { int parmFloatCount = HAPI_ParmInfo_GetFloatValueCount( &parmInfos[ i ] ); float * parmFloatValues = new float[ parmFloatCount ]; ENSURE_SUCCESS( HAPI_GetParmFloatValues( &session, nodeId, parmFloatValues, parmInfos[ i ].floatValuesIndex, parmFloatCount ) ); for ( int v = 0; v < parmFloatCount; ++v ) { if ( v != 0 ) std::cout << ", "; std::cout << parmFloatValues[ v ]; } delete [] parmFloatValues; } else if ( HAPI_ParmInfo_IsString( &parmInfos[ i ] ) ) { int parmStringCount = HAPI_ParmInfo_GetStringValueCount( &parmInfos[ i ] ); HAPI_StringHandle * parmSHValues = new HAPI_StringHandle[ parmStringCount ]; ENSURE_SUCCESS( HAPI_GetParmStringValues( &session, nodeId, true, parmSHValues, parmInfos[ i ].stringValuesIndex, parmStringCount ) ); for ( int v = 0; v < parmStringCount; ++v ) { if ( v != 0 ) std::cout << ", "; std::cout << getString( parmSHValues[ v ] ); } delete [] parmSHValues; } std::cout << ")" << std::endl; } delete [] parmInfos; char in; std::cout << "Press any key to exit" << std::endl; std::cin >> in; HAPI_Cleanup( &session ); return 0; } static std::string getLastError() { int bufferLength; HAPI_GetStatusStringBufLength( nullptr, HAPI_STATUS_CALL_RESULT, HAPI_STATUSVERBOSITY_ERRORS, &bufferLength ); char * buffer = new char[ bufferLength ]; HAPI_GetStatusString( nullptr, HAPI_STATUS_CALL_RESULT, buffer, bufferLength ); std::string result( buffer ); delete [] buffer; return result; } static std::string getLastCookError() { int bufferLength; HAPI_GetStatusStringBufLength( nullptr, HAPI_STATUS_COOK_RESULT, HAPI_STATUSVERBOSITY_ERRORS, &bufferLength ); char * buffer = new char[ bufferLength ]; HAPI_GetStatusString( nullptr, HAPI_STATUS_COOK_RESULT, buffer, bufferLength ); std::string result( buffer ); delete[] buffer; return result; } static std::string getString( HAPI_StringHandle stringHandle ) { if ( stringHandle == 0 ) { return ""; } int bufferLength; HAPI_GetStringBufLength( nullptr, stringHandle, &bufferLength ); char * buffer = new char[ bufferLength ]; HAPI_GetString ( nullptr, stringHandle, buffer, bufferLength ); std::string result( buffer ); delete [] buffer; return result; } |
用pyhapi的话十行以内
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import pyhapi as ph def main(): session = ph.HSessionManager.get_or_create_default_session() #load hda asset and instantiate hda_asset = ph.HAsset(session, "hda/SideFX_spaceship.otl") asset_node = hda_asset.instantiate(node_name="Spaceship") #Query node's parameters for name in asset_node.get_param_names(): print("Query param: {0} has value: {1}".format(name, asset_node.get_param_value(name))) if __name__ == "__main__": main() |
当然我们还可以把一个模型/曲线，传入/取出houdini engine，比如mesh_marshall_input.py这个例子，传进去一个方块，然后做了细分
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# -*- coding: utf-8 -*- """Example of setting mesh data into hengine Author : Maajor Email : hello_myd@126.com """ import numpy as np import pyhapi as ph def main(): """Main """ session = ph.HSessionManager.get_or_create_default_session() #create an inputnode where you can set geometry geo_inputnode = ph.HInputNode(session, "Cube") #create a geomesh cube_geo = ph.HGeoMesh( vertices=np.array( [[0.0, 0.0, 0.0], [0.0, 0.0, 1.0], [0.0, 1.0, 0.0], [0.0, 1.0, 1.0], [1.0, 0.0, 0.0], [1.0, 0.0, 1.0], [1.0, 1.0, 0.0], [1.0, 1.0, 1.0]], dtype=np.float32), faces=np.array( [[0, 2, 6, 4], [2, 3, 7, 6], [2, 0, 1, 3], [1, 5, 7, 3], [5, 4, 6, 7], [0, 4, 5, 1]], dtype=np.int32)) #set this geomesh as geometry of inputnode geo_inputnode.set_geometry(cube_geo) #create a node whose input is inputnode ph.HNode(session, "Sop/subdivide", "Cube Subdivider").connect_node_input(geo_inputnode) session.save_hip() if __name__ == "__main__": main() |
内部实现
Python可以和C很好地实现交互。类似其他几个平台：Unity 用的c#，dllimport就行；Unreal就是cpp，include进来就行
Python用ctypes就能加载dll
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sys = platform.system() if sys == "Windows": HAPI_LIB = ctypes.cdll.LoadLibrary("libHAPIL") elif sys == "Linux": HAPI_LIB = ctypes.cdll.LoadLibrary("libHAPIL.so") |
这就直接可以调用libHAPIL的方法了
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HAPI_LIB.HAPI_IsSessionValid(byref(session)) |
源码里hapi.py里全部是对libHAPIL的封装，hdata.py里全是houdini engine的struct
除此以外，hsession封装session对象，hnode封装node对象，hgeo封装geo对象，hasset封装HDA对象。总共就这六个文件
可以干什么
为了Houdini Pipeline咯
可以做：
- 资产自动化处理
- HDA自动化测试
- HDA管理
- etc…
最后， 祝读者春节快乐，百病不侵！
参考资料
Houdini Engine API Documentation
Houdini Engine API入門 日本人jyouryuusui写的，作者介绍了下API用法，写了个Qt UI调用Houdini Engine C API
Intro to Houdini Engine Scripting API 官网上2014年的教程，有点老，当时还是Houdini13
牛！！！