void Terrain_Paint(int x, int y)
{
	ENTITY* Terr = Terrain[x][y];
	CONTACT* c1;
	int i; //vertex info for terrain
	
	BMAP* Source_BM;
	
	BMAP* OldSkin;
	VECTOR Pixel_pos; //pixel coordinates for skin bmap
	
	var height;
	
	var pixel_source; var pixel_dest;
	//var t_format1; var t_format2;
	COLOR* t_color; var t_alpha; 
	
	BMAP* NewSkin = bmap_create("Terrain_Sand.tga");
	t_format1=bmap_lock(NewSkin,0);
	
	c1 = ent_getvertex(Terr,NULL,1);
	
	for(Pixel_pos.y=0;Pixel_pos.y<512;Pixel_pos.y++)
	{
		for(Pixel_pos.x=0;Pixel_pos.x<512;Pixel_pos.x++)
		{
			i = (integer((Pixel_pos.x)/16)+1) + (((integer((Pixel_pos.y)/16)+1)*33));
			height = get_height(Pixel_pos.x,Pixel_pos.y,i,c1);
			
			if(height>16)
			{
				if(height<=16)//sand
				{
					Source_BM=Sand_BM;
				}
				else if(height<75)//grass
				{
					Source_BM=Grass_BM;
				}
				else if(height<150)//stone
				{
					Source_BM=Rock_BM;
				}
				else//snow
				{
					Source_BM=Snow_BM;
				}
				pixel_source = pixel_for_bmap(Source_BM,Pixel_pos.x,Pixel_pos.y);
				t_color = pixel_to_vec(NULL, t_alpha ,t_format2,pixel_source);
				
				//paint pixel on selected terrain's texture
				pixel_dest=pixel_for_vec(t_color,t_alpha,t_format1);
				pixel_to_bmap(NewSkin,Pixel_pos.x,Pixel_pos.y,pixel_dest);
			}
		}
	}

	bmap_unlock(NewSkin);
	OldSkin=ent_getskin(Terr,1);
	ptr_remove(OldSkin);
	ent_setskin(Terr,NewSkin,1);
}

var get_height(var Px, var Py, int SW, CONTACT* c1)
{
	//P = point that we want the height of (x,y,0)
	//SW = vertex number of terrain ent closest towards the lower left corner of the square
	//c1 = pointer to our terrain vertex info
	
	
	VECTOR P;
	//TRANSFORM SKIN PIXEL COORDS TO LOCAL ENT COORD SYSTEM
	vec_set(P,vector(Px,Py,0));
	P.x-= 256;
	P.y = 256-P.y;
	
	VECTOR Triangle[3];
	VECTOR temp_vec;
	ANGLE temp_ang;
	VECTOR Director[2];
	
	VECTOR formula;
	var ind_term;
	
	//retrieve first point of containing triangle (base corner)
	Triangle[0].x=(c1.v)[SW].x;
	Triangle[0].y=(c1.v)[SW].z;
	Triangle[0].z=(c1.v)[SW].y;
	
	//retrieve second point of containing triangle (diagonal to base)
	Triangle[1].x=(c1.v)[SW-32].x;
	Triangle[1].y=(c1.v)[SW-32].z;
	Triangle[1].z=(c1.v)[SW-32].y;
	
	//determine third point of containing triangle (varying point)
	vec_set (temp_vec, P);
	vec_sub (temp_vec,Triangle[0].x);
	vec_to_angle (temp_ang.pan,temp_vec);
	
	//retrieve third point of containing triangle (varying point)
	if(temp_ang.pan>45)
	{
		Triangle[2].x = (c1.v)[SW-33].x;
		Triangle[2].y = (c1.v)[SW-33].z;
		Triangle[2].z = (c1.v)[SW-33].y;
		
	}
	else
	{
		Triangle[2].x = (c1.v)[SW+1].x;
		Triangle[2].y = (c1.v)[SW+1].z;
		Triangle[2].z = (c1.v)[SW+1].y;
		
	}
	
	//calculate the triangle's plane normal for the formula coeficients
	vec_set(Director[0],Triangle[1]);
	vec_sub(Director[0],Triangle[0]);
	vec_set(Director[1],Triangle[2]);
	vec_sub(Director[1],Triangle[0]);
	vec_cross(formula,Director[0],Director[1]);
	//set the independant term of the formula
	ind_term=(-1*formula.x*Triangle[0].x)+(-1*formula.y*Triangle[0].y)+(-1*formula.z*Triangle[0].z);
	//calculate our point's height plugging our values into the formula
	P.z=(-1*((formula.x*P.x)+(formula.y*P.y)+ind_term))/formula.z;
	return(P.z);
}