Method preload

src/cinder/GeomIo.cpp:4970–4988

}

void SourceModsContext::preload( const AttribSet &requestedAttribs )
{
	if( ! mSource ) {
		CI_LOG_E( "SourceModsContext::preload() called with a NULL source." );
		return;
	}

	// If we have modifiers, initiate the chain by calling the last modifier's process() method.
	// This in turn will call processUpstream(), which will call the next modifier's process(), until there
	// are no remaining modifiers. Finally processUpstream() will call loadInto() on the Source
	if( ! mModiferStack.empty() ) {
		auto modifier = mModiferStack.back();
		mModiferStack.pop_back();
		modifier->process( this, requestedAttribs );
	}
	else { // no modifiers; just loadInto on the soucre directly
		mSource->loadInto( this, requestedAttribs );
	}
}

// Expects preload() to have been called on 'rhs'
void SourceModsContext::combine( const SourceModsContext &rhs )