VEX JSON Bindings

Introduction

This repo is an attempt to provide a small set of VEX functions that gives access to JSON entries in VEX.

Features

• shared, threadsafe storage
• access to data through variadic arguments
• detailed error reporting
• no external dependencies

Installation

Compiled DSO place into ~/houdiniX.X/dso/vex directory. In addition you need to add an entry to ~/houdiniX.X/vex/VEXdso: vex/libVEX_json.so.

Functions:

• jsonvalue access values
• jsonkeys access dictionary keys
• jsontype returns string representation of the type

Supported return data types:

• simple, such as: int, float and string
• arrays of: int, float and string
• dictionary keys as array of string
• vector and matrix types can be handled by VEX unserialize function.

Function declarations

• int jsonvalue(string inputFile, string& outputError, type& output, ... );

  int jsonvalue(string inputFile, string& outputError, type& output[], ... );

  returns value at specified path, if path is not found returns error.

• int jsontype(string inputFile, string& outputError, string& output, ... );

  type at path: bool, int, float, string, key, array, map

• int jsonkeys(string inputFile, string& outputError, string& output[], ... );

  dictionary keys at given path

Function arguments

• int return value: 0 - failure to get value, 1 - success
• string inputPath a full path to the JSON file
• string& outputError error message
• type& output returned value
• ... variadic arguments, a path to the value, accepts string or int type only.

Numeric data precission

Numeric data types are casted automatically based on provided output argument. For instance JSON int data can be read as float. Same for float can be read as int, but beware of precission loss.

Compilation and dependencies

JSON parsing is based on HDK's UT_JSONValue utility class, therefore compilation doesn't require any external dependencies. For smart pointers standard library is used, for caching tbb::map and tbb::unordered_set.

Example JSON

JSON file:

{
    "abc_geo_count": 30,
    "anim_end": 1123,
    "anim_start": 1001,
    "asset_name": "Peter",
    "asset_scale": 1.1,
    "asset_type": "Character",
    "cache_by": 1.0,
    "cache_end": 1126,
    "cache_start": 998,
}

VEX functions to retrieve values:

string json = ".../example2.json";
string error;
string keys[];
if(!jsonkeys(json, error, keys ))
{
    error(error);
}

foreach(string key; keys)
{
    string type;
    if(!jsontype(json, error, type, key))
    {
        error(error);
    }
    
    if(type == "int")
    {
        int value;
        if(!jsonvalue(json, error, value, key))
        {
            error(error);
        }
        setpointattrib(geoself(), key, i@ptnum, value);
    }
    else if(type == "float")
    {
        float value;
        if(!jsonvalue(json, error, value, key))
        {
            error(error);
        }
        setpointattrib(geoself(), key, i@ptnum, value);
    }
    else if(type == "string")
    {
        string value;
        if(!jsonvalue(json, error, value, key))
        {
            error(error);
        }
        setpointattrib(geoself(), key, i@ptnum, value);
    }
    
}

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.