Here is a simple snowing script.
It is a demo with a simple black box getting more and more covered with white dots.
snowing demo
The dots are very small (it depends on the size of the skin), so I want to add additional painting around the dots, but when I use the following part, it shows weird effects and eventually crashes. Maybe, someone has an idea to solve this issue?
Thanks in advance.
Code:
while(coords_cur_x <= (coords_x + coords_area))
			{
				pixel_to_bmap(canvas,coords_cur_x, coords_cur_y,pixel);
				coords_cur_y += 1;
				if(coords_cur_y > (coords_y + coords_area))
				{
					coords_cur_x += 1;
					coords_cur_y = coords_y - coords_area;
				}
			}



This is the whole script.
Code:
#include <litec.h>
#include <d3d9.h>

#include <acknex.h>
#include <default.c>

#define PRAGMA_ZERO

BMAP* canvas;

var format; 
var pixel;
var coords_x;
var coords_y;

function snowing()
{
	while(1)
	{
		c_trace(vector(random(30)-15,random(30)-15, 100), vector(random(30)-15,random(30)-15, -100), IGNORE_PASSABLE | IGNORE_ME | SCAN_TEXTURE | ACTIVATE_SHOOT);
		wait(1);				
	}	
}

function snowEvent()
{
	coords_x = hit.u1;
	coords_y = hit.v1;
}

action get_snow()//needs an own variable to prevent it from colliding with similar tarrain actions
{
	set(my, POLYGON);
 	my.emask |= ENABLE_SHOOT;
  	my.event = snowEvent;
	while(1)
	{
//		if(mouse_left)
//		{
//			while(mouse_left){wait(1);}
//			coords_x = random(10);
//			coords_y = random(10);
			var coords_area = 1;
			var coords_cur_x = coords_x - coords_area;
			var coords_cur_y = coords_y - coords_area;
			canvas = bmap_for_entity(my, 0);	//1 is the number of the skin
	
			format = bmap_lock(canvas, 0); // lock the canvas bitmap
			pixel = pixel_for_vec(vector(255,255,255), 100, format);
			pixel_to_bmap(canvas, coords_x, coords_y, pixel); // now write the pixel at the coords_x, coords_y position
//			while(coords_cur_x <= (coords_x + coords_area))
//			{
//				pixel_to_bmap(canvas,coords_cur_x, coords_cur_y,pixel);
//				coords_cur_y += 1;
//				if(coords_cur_y > (coords_y + coords_area))
//				{
//					coords_cur_x += 1;
//					coords_cur_y = coords_y - coords_area;
//				}
//			}
			bmap_unlock(canvas); // unlock the bitmap now
			bmap_to_mipmap(canvas);
//		}
		wait(1);
	}
}

function main()
{
	level_load(NULL);
	camera.z = 30;
	camera.tilt = -90;
	ent_create("cube_black.mdl", vector(0,0,0), get_snow);
	snowing();
}