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

//bitmap to be generated
BMAP* map;

//tile bmaps
BMAP* tile1 = "plain001.tga";
BMAP* tile2 = "plain002.tga";

//display for our bitmap
PANEL* viewer =
{
	pos_x = 5;
	pos_y = 5;
	layer = 10;
	alpha = 100;
	flags = SHOW | TRANSLUCENT;
}

//small utility function to ensure vector components are smaller than a certain value
void vec_trunc(var *vec, var limit)
{
	vec[0] = minv(vec[0], limit);
	vec[1] = minv(vec[1], limit);
	vec[2] = minv(vec[2], limit);
}

//adds feature bitmap to the map at the (X,Y) position. you have to manually lock and unlock bitmaps
void add_bmap(var X, var Y, BMAP *map, var map_format, BMAP *feature, var feature_format)
{
	var temp_map_pixel[3];
	var temp_feature_pixel[3];
	var temp_map_alpha;
	var temp_feature_alpha;

	var i, j;
	for(i = 0; i < bmap_width(feature); i++)
	{
		for(j = 0; j < bmap_height(feature); j++)
		{
			//ensure we stay within main bitmap bounds to prevent engine crashing
			if(X+i >= bmap_width(map) || Y+j >= bmap_height(map)) continue;
			
			//read map pixel
			pixel_to_vec(temp_map_pixel, temp_map_alpha, map_format, pixel_for_bmap(map, X+i, Y+j));
			//read feature pixel
			pixel_to_vec(temp_feature_pixel, temp_feature_alpha, feature_format, pixel_for_bmap(feature, i, j));
			
			//color mixing in 3 steps
			//1.multiply feature pixel's color with normalized alpha
			vec_scale(temp_feature_pixel, temp_feature_alpha/100);
			//2.add resulting color to the map pixel's color
			vec_add(temp_map_pixel, temp_feature_pixel); 
			//3.check that resulting vector components stay within 0-255 range
			vec_trunc(temp_map_pixel, 255);
			
			//write the resulting color to the map
			pixel_to_bmap(map, X+i, Y+j, pixel_for_vec(temp_map_pixel, temp_map_alpha, map_format));
		}
	}
}

void main()
{
	level_load(NULL);
	wait(3);
	
	//create a blank map
	map = bmap_createblack(512, 512, 32);
	bmap_fill(map, vector(1,1,1), 100);
	viewer.bmap = map;
	
	var i;//our index var

	//lock main bitmap
	var map_format = bmap_lock(map, 0);

	//lock first feature bitmap - called only once instead of locking\unlocking bitmap every time
	var feature_format = bmap_lock(tile1, 0);
	
	//add 20 features at random positions
	for(i = 0; i < 20; i++)
	{
		add_bmap(random(bmap_width(map)), random(bmap_height(map)), map, map_format, tile1, feature_format);
	}
	
	//we're done with first feature - can unlock it's bitmap
	bmap_unlock(tile1);
	
	//do the same routine for the second feature type
	var feature_format = bmap_lock(tile2, 0);
	
	for(i = 0; i < 20; i++)
	{
		add_bmap(random(bmap_width(map)), random(bmap_height(map)), map, map_format, tile2, feature_format);
	}
	
	bmap_unlock(tile2);
	
	//unlock main bitmap
	bmap_unlock(map);
}