#include "gbaio.h"

#define O 0x01,
#define _ 0x00,

char sf1[] = {
					_ O _ _ _ O _ _
					O O _ O _ O _ _
					_ O O _ O O O _
					O _ _ O O _ _ _
					O _ O _ O _ O _
					_ _ O _ O O _ _
					_ O O _ O _ O _
					_ _ _ _ _ _ _ _		};

char sf2[] = {
					_ _ _ _ O _ _ _
					_ _ O _ _ _ O _
					_ O _ O O O _ _
					_ O O O _ O _ O
					_ _ _ O O O _ _
					_ _ O _ _ O _ O
					_ O _ O _ O _ _
					_ _ _ _ _ _ _ _		};

char sf3[] = {
					_ _ _ _ _ _ _ _
					_ _ _ O _ O _ _
					_ _ _ O _ _ _ _
					_ O _ O O O _ O
					_ _ O O O _ O _
					_ O _ _ _ O O _
					_ O _ O _ O _ O
					_ _ O _ _ _ O _		};

char sf4[] = {
					_ _ _ _ _ _ _ _
					_ _ _ O _ _ _ _
					_ O O _ O _ _ _
					_ O _ O _ O _ _
					O _ O O O O O _
					_ O _ O _ O _ _
					O _ O _ O _ O _
					_ _ _ O _ O _ _		};


#undef O
#undef _
			//these chars are loaded into memory before the main function even begins

int main(void) {

start_game();

load_image(1, sf1, IMAGE_8x8);	//image number 1,2,3, and 4 are each associated with the chars above,
load_image(2, sf2, IMAGE_8x8);	//so these 4 image numbers point to the images in the sf1,sf2,sf3, and sf4 images respectively.
load_image(3, sf3, IMAGE_8x8);
load_image(4, sf4, IMAGE_8x8);

int sf[30], i, sfx[30], sfy[30];
float speed=1;  //speed is a float, not an int, so it can be changed by .01

for (i=0; i<30; i++) {    	//this for loop counter sets i to 0, runs through the following "body", adds one to i, and
							//then, if i is still less than 30, it goes through the following body again, adds one to i, and
							//then, if i is still less than 30, it goes through the following body again, adds one to i, and
							//so on until i is 30.
	sf[i]=i;				//assign initial number to each of the variables in this array of all the sprite numbers
	sfx[i]=rand(0,300);	//assign initial number to each of the variables in this array of all the sprite x's  
	sfy[i]=-8;				//assign initial number to each of the variables in this array of all the sprite y's
	}
	
for (i=0; i<30; i++)
	set_sprite_image(sf[i], rand(1,4)); //each of the sprite numbers in the sf[30] array, which are numbered 0-29,
										 //are taken one at a time and a random image number from 1 to 4 is associated with those sprite numbers
while (1) {

	start_input();						// wake up and smell the buttons, GBA
		if (button_held(A_BUTTON))		// press the a or b button to change the snowflake speed
			speed = speed+0.01;
		if (button_held(B_BUTTON))
			speed = speed-0.01;

	for (i=0; i<30; i++) {				//run through the following, but each time increase the variable i by one.
										//i starts at 0, and end this loop when i hits 30.
		sfx[i]=sfx[i]+rand(-3*speed, 3*speed);		//Take the snowflake x in the sfx[30] array that corrisponds to what i is for this run through 
													//the loop and add a random number between -3s and 3s where s is how fast my snowflakes are going.
		sfy[i]=sfy[i]+rand(1*speed, 3*speed);		//Do the same thing with y, but instead of adding a random number between -3s and 3s, add a random 
													//number between s and 3s.  This makes the snowflakes go down and not up, but randomly side to side.
		if (sfy[i]>270) {							//On each run through this for loop, if the snowflake y in the sfy[i] array that corrisponds to what 
													//i is for this run through the loop is at the bottom, then
		set_sprite_image(sf[i], rand(1,4));		//change that snowflake's image to a random snowflake image and
		sfy[i] = -8;								//move it to the top, or, more accurately, above the top of the screen, just off screen.
		};
	};
		start_drawing();				//wait until the right moment, so it doesn't look like a broken TV, and then show the changes made above
	for (i=0; i<30; i++)				//another counter from 0 to 29.  It runs through the body of this for loop, then adds 1 to i, then starts over
										//until adding 1 to i makes it 30
		draw_sprite(i, sfx[i], sfy[i]);//for each run through this loop, the sprite at sprite number i is drawn 
										//at the snowflake x in the sfx[30] array that is equal to i and
										//at the snowflake y in the sfy[30] array that is equal to i.
										//You have to understand how this draws all the sprites, one on each trip through this loop,
										//in order to understand what you're changing in the code above.
										//In other words, the manipulated arrays don't mean anything until they're drawn,
										//so you have to know how they're being used in the draw_sprite function to know how to manipulate them.
	}
	
	return 0; 

}