getAttribLocation(name) {
		const attr = this.attributes[name];
		if (typeof attr !== "undefined") {
			return attr;
		} else {
			return -1;
		}
	}
returns the location of an attribute variable in this shader program
@param {string} name - the name of the attribute variable whose location to get.
@returns {GLint} number indicating the location of the variable name if found. Returns -1 otherwise