Dynamic Rain Shader
This resource pack transforms rain in Minecraft using built-in shader capabilities without requiring additional mods. It changes the angle of falling raindrops, making them appear more natural and realistic compared to the standard straight vertical direction.
Beyond altering rain trajectory, the resource pack also enhances several related visual effects. Raindrop textures receive new designs for greater realism, and impact splashes have been redesigned to maintain visual consistency. Additionally, clouds become transparent with improved fog gradients, creating a more atmospheric sky during precipitation.

Future versions plan to modify water dripping particles that flow down blocks, which in the standard version have a fixed dark blue color and don't match the updated aesthetic.
Compatibility
Dynamic Rain is compatible with Sodium, although sometimes this mod can disrupt standard and modified rendering in Minecraft. When issues occur, installing Indium is recommended, as it fixes such problems, though additional solutions aren't usually necessary.
Important limitation: The resource pack doesn't work with shader packs
Technical Features
The resource pack operates through a vertex shader that identifies a specific alpha channel value in the rain texture (38% opacity) and rotates the particle matrix to change the angle. Transparent backgrounds are required for proper texture display, so the fragment shader performs masking, removing the green background and leaving only raindrops.
The author notes that the code could have been implemented more efficiently, as this is an experimental development using shaders. More optimal methods for declaring and modifying matrices may be suggested by experienced developers.