How seamless noise works: Instead of sampling flat 2D noise (which has hard edges), we map each (x,y) pixel coordinate onto the surface of a 4D torus using cos/sin pairs: (cos(2πx), sin(2πx), cos(2πy), sin(2πy)). Because a circle wraps perfectly, the noise is automatically periodic — left edge equals right edge, top equals bottom. No blending or mirroring needed.