Using normalized global positions to create an up and down gradient.

Atmospheric rendering, this function is shared with all the other shaders. Same logic as gradient up & down, i use normalized world pos to create height gradient. I also added the the sun and moon impact on the atmospheric rendering.

To render the clouds, I used a 2D raymarching technique that involves layering the same 2D texture at different height levels while applying a bell-shaped gradient (0->1->0). To light the clouds, we sample the same texture, but with an offset.

For the moon and sun masks, I use world positions that are aligned with the sun rotation and then transformed into spherical coordinates to sample a 2D texture.

For the stars, I sample a 3D texture that rotates around an axis. I also sample a 3D noise to create a twinkling star effect.

All shader graph.