SimplexNoise2D.snoise_vec2(0.1, 0.5)
SimplexNoise3D.snoise_vec3(0.1, 0.5, 0.1)
snoise_vec4(vec4.fromValues(0.1, 0.5, 0.1, 1.0))
For more precision use Float64Array or Array instead of Float32Array in glMatrix.