function getMaxShaderPrecision(gl) {
	if (
		gl.getShaderPrecisionFormat(gl.VERTEX_SHADER, gl.HIGH_FLOAT).precision >
			0 &&
		gl.getShaderPrecisionFormat(gl.FRAGMENT_SHADER, gl.HIGH_FLOAT).precision > 0
	) {
		return "highp";
	}
	if (
		gl.getShaderPrecisionFormat(gl.VERTEX_SHADER, gl.MEDIUM_FLOAT).precision >
			0 &&
		gl.getShaderPrecisionFormat(gl.FRAGMENT_SHADER, gl.MEDIUM_FLOAT).precision >
			0
	) {
		return "mediump";
	}
	return "lowp";
}
return the highest precision format supported by this device for GL Shaders
@ignore
@param {WebGLRenderingContext} gl - the current WebGL context
@returns {boolean} "lowp", "mediump", or "highp"