Day-light transitions ,non-lagging rain and underwater effect

Hi, guys

What I am asking for maybe others talked about it. First of all how to simulate day-light transitions? i.e. which value should I change? sun_light or sun_color or what?

Also, I want to make a rain effect that doesn't cause lagging. Maybe, using particle effects ,but I can't figure out the code. Every time I try some code ,the engine crashes or it simply doesn't work. Also, I downloaded some code snippet but it was WDL script and I am using Lite-C


In the end, I want to learn how to make underwater effect? Also, what value should I change?

NOTE 1: Please, don't give me shader & material hard stuff. I want first to understand the code before I use it

NOTE 2: I want any code in Lite-C script ,not in WDL as I always have hard time changing it into Lite-C ,and at the end, I can't



Thank you for reading

mystimoods has a lite-c conversion and features both things: http://www.loopix-project.com/

shortly:

1) you can tweak sun_angle.pan and .tilt to set Sun position (a short time ago there was a contribution that sets it perfectly), sun_color to set a proper color, and sun_light to decrease sun_color brightness.

2) see TUST for effects, or mystimoods again

3) probably you need a blueish fog. if you can use shaders you can take the caustic shader from mystimoods simulating underwater lights, and maybe a refraction post process shader to distort the view a bit