processSampler( map ) {

    		const json = this.json;

    		if ( ! json.samplers ) json.samplers = [];

    		const samplerDef = {
    			magFilter: THREE_TO_WEBGL[ map.magFilter ],
    			minFilter: THREE_TO_WEBGL[ map.minFilter ],
    			wrapS: THREE_TO_WEBGL[ map.wrapS ],
    			wrapT: THREE_TO_WEBGL[ map.wrapT ]
    		};

    		return json.samplers.push( samplerDef ) - 1;

    	}
Process sampler
@param  {Texture} map Texture to process
@return {Integer}     Index of the processed texture in the "samplers" array