====== Example: Hello, World ======
This is just about the simplest functional example possible. It demonstrates:

  * Setting up error and message callbacks.
  * Allocating and deleting a SpeedTree Engine object.
  * Loading a SpeedTree model file ([[input|STE or SPM]]).


<code cpp-qt>
#include <cstdio>
#include "speedtree_engine.h"

///////////////////////////////////////////////////////////////////////
//  SpeedTree Engine API error callback

static void MyEngineApiErrorCallback(const char* pError)
{
    fprintf(stderr, "    **[Error Report from SpeedTree Engine API]**: %s\n", pError);
}


///////////////////////////////////////////////////////////////////////
//  SpeedTree Engine API message callback

static void MyEngineApiMessageCallback(const char* pMessage)
{
    fprintf(stderr, "    [Message from SpeedTree Engine API]: %s\n", pMessage);
}


///////////////////////////////////////////////////////////////////////
//  Example_HelloWorld

bool Example_HelloWorld(const char* pModelFilename)
{
    bool bSuccess = false;

    // register callback message functions; when api calls fail, messages will be sent here
    SteSetErrorFunction(MyEngineApiErrorCallback);
    SteSetMessageFunction(MyEngineApiMessageCallback);

    // uses a C interface -- objects are created and initialized through function calls
    SSteEngine* pEngine = SteNew( );
    if (pEngine)
    {
        // this causes the model file to be loaded and parsed, but nothing is computed yet
        if (SteLoadSpeedTreeFile(pEngine, pModelFilename) == STE_SUCCESS)
        {
            printf("Hello, world. SpeedTree model loaded successfully.\n");
            bSuccess = true;
        }
        else
        {
            // if there's a failure, a message will be sent via the callback
        }

        // using C, so no destructors
        SteDelete(pEngine);
    }

    return bSuccess;
}
</code>