Houdini Plugin Development

Build Houdini Digital Assets (HDAs) and plugins using msvc-kit.

Requirements

Houdini Version	MSVC Version	Windows SDK
Houdini 20.5	14.38	10.0.22621.0
Houdini 20.0	14.34	10.0.22000.0
Houdini 19.5	14.32	10.0.19041.0
Houdini 19.0	14.29	10.0.19041.0

Setup

1. Download MSVC

# For Houdini 20.5
msvc-kit download --msvc-version 14.38 --sdk-version 10.0.22621.0

2. Setup Environment

msvc-kit setup --script --shell powershell | Invoke-Expression

3. Set Houdini Environment

$env:HFS = "C:\Program Files\Side Effects Software\Houdini 20.5.xxx"
$env:PATH = "$env:HFS\bin;$env:PATH"

Building with hcustom

Houdini provides hcustom for building plugins:

# Setup MSVC environment
msvc-kit setup --script --shell powershell | Invoke-Expression

# Build with hcustom
& "$env:HFS\bin\hcustom.exe" SOP_MyNode.cpp

Manual Build

Simple SOP Plugin

// SOP_Star.cpp
#include <SOP/SOP_Node.h>
#include <OP/OP_Operator.h>
#include <OP/OP_OperatorTable.h>
#include <PRM/PRM_Include.h>
#include <GU/GU_Detail.h>
#include <UT/UT_DSOVersion.h>

class SOP_Star : public SOP_Node {
public:
    static OP_Node* myConstructor(OP_Network*, const char*, OP_Operator*);
    static PRM_Template myTemplateList[];
    
protected:
    SOP_Star(OP_Network* net, const char* name, OP_Operator* op);
    virtual ~SOP_Star();
    virtual OP_ERROR cookMySop(OP_Context& context);
};

// Implementation...

void newSopOperator(OP_OperatorTable* table) {
    table->addOperator(new OP_Operator(
        "star", "Star",
        SOP_Star::myConstructor,
        SOP_Star::myTemplateList,
        0, 0
    ));
}

Compile

msvc-kit setup --script --shell powershell | Invoke-Expression

# Get Houdini compile flags
$HOUDINI_CFLAGS = & "$env:HFS\bin\hcustom.exe" -c
$HOUDINI_LDFLAGS = & "$env:HFS\bin\hcustom.exe" -m

# Compile
cl /c /O2 /MD /EHsc $HOUDINI_CFLAGS SOP_Star.cpp

# Link
link /DLL /OUT:SOP_Star.dll SOP_Star.obj $HOUDINI_LDFLAGS

CMake Build

CMakeLists.txt

cmake_minimum_required(VERSION 3.20)
project(HoudiniPlugin)

set(CMAKE_CXX_STANDARD 17)

# Find Houdini
set(HOUDINI_ROOT "C:/Program Files/Side Effects Software/Houdini 20.5.xxx"
    CACHE PATH "Houdini installation path")

# Get Houdini configuration
execute_process(
    COMMAND "${HOUDINI_ROOT}/bin/hcustom.exe" -c
    OUTPUT_VARIABLE HOUDINI_CFLAGS
    OUTPUT_STRIP_TRAILING_WHITESPACE
)

execute_process(
    COMMAND "${HOUDINI_ROOT}/bin/hcustom.exe" -m
    OUTPUT_VARIABLE HOUDINI_LDFLAGS
    OUTPUT_STRIP_TRAILING_WHITESPACE
)

# Plugin
add_library(SOP_Star SHARED
    src/SOP_Star.cpp
)

target_include_directories(SOP_Star PRIVATE
    ${HOUDINI_ROOT}/toolkit/include
)

target_compile_options(SOP_Star PRIVATE ${HOUDINI_CFLAGS})
target_link_options(SOP_Star PRIVATE ${HOUDINI_LDFLAGS})

set_target_properties(SOP_Star PROPERTIES
    SUFFIX ".dll"
    PREFIX ""
)

Build

msvc-kit setup --script --shell powershell | Invoke-Expression

cmake -B build -G "NMake Makefiles" -DCMAKE_BUILD_TYPE=Release
cmake --build build

VEX Custom Functions

VEX DSO

#include <UT/UT_DSOVersion.h>
#include <VEX/VEX_VexOp.h>

static void my_vex_func(int argc, void* argv[], void*) {
    float* result = (float*)argv[0];
    float input = *(float*)argv[1];
    *result = input * 2.0f;
}

void newVEXOp(void*) {
    new VEX_VexOp("my_func@&FF", my_vex_func);
}

Build VEX DSO

msvc-kit setup --script --shell powershell | Invoke-Expression

cl /c /O2 /MD /EHsc `
   /I"$env:HFS\toolkit\include" `
   my_vex_func.cpp

link /DLL /OUT:my_vex_func.dll `
     my_vex_func.obj `
     /LIBPATH:"$env:HFS\custom\houdini\dsolib"

Library API Usage

use msvc_kit::{download_msvc, download_sdk, setup_environment, DownloadOptions};
use std::process::Command;

async fn build_houdini_plugin(houdini_version: &str) -> msvc_kit::Result<()> {
    let msvc_version = match houdini_version {
        "20.5" => "14.38",
        "20.0" => "14.34",
        "19.5" => "14.32",
        _ => "14.38",
    };
    
    let options = DownloadOptions {
        msvc_version: Some(msvc_version.to_string()),
        ..Default::default()
    };
    
    let msvc = download_msvc(&options).await?;
    let sdk = download_sdk(&options).await?;
    let env = setup_environment(&msvc, Some(&sdk))?;
    
    // Setup environment
    std::env::set_var("INCLUDE", env.include_path_string());
    std::env::set_var("LIB", env.lib_path_string());
    
    let hfs = format!("C:\\Program Files\\Side Effects Software\\Houdini {}.xxx", houdini_version);
    
    // Use hcustom
    Command::new(format!("{}\\bin\\hcustom.exe", hfs))
        .arg("SOP_MyNode.cpp")
        .status()?;
    
    Ok(())
}

Installation

Copy the built DSO to Houdini's plugin directory:

$HOUDINI_USER = "$env:USERPROFILE\Documents\houdini20.5"
Copy-Item SOP_Star.dll "$HOUDINI_USER\dso\"

Or set HOUDINI_DSO_PATH:

$env:HOUDINI_DSO_PATH = "C:\MyPlugins;&"

Troubleshooting

"Cannot find Houdini headers"

Check HFS environment variable:

echo $env:HFS
Test-Path "$env:HFS\toolkit\include\SOP\SOP_Node.h"

Version Mismatch

Ensure MSVC version matches Houdini's build:

& "$env:HFS\bin\houdini.exe" -version

DSO Not Loading

Check Houdini's console for errors:

Houdini > Windows > Shell