ball.lua

--ball
clr=10
rad=2
x_prev=0
y_prev=0

function draw_ball()
	for ball in all(balls) do
		if ball.stuck then
			-- line(ball.x+ball.dx*4,ball.y+ball.dy*4,ball.x+ball.dx*7,ball.y+ball.dy*7,blink_2)
			local col1, col2, col3, col4 = getblinkcols()
			pset(ball.x+ball.dx*5,ball.y+ball.dy*5,col1)
			pset(ball.x+ball.dx*7,ball.y+ball.dy*7,col2)
			pset(ball.x+ball.dx*9,ball.y+ball.dy*9,col3)
			pset(ball.x+ball.dx*11,ball.y+ball.dy*11,col4)
		end
		if t_mega > 0 then
			circfill(ball.x,ball.y,rad,8)
			circ(ball.x,ball.y,rad,5)
		else
			circfill(ball.x,ball.y,rad,10)
		end
	end
end

function move_ball(ball)
	local x, dx, dy = ball.x, ball.dx, ball.dy
	--updates ball position
--	x_prev=x
--	y_prev=y
	if t_speed > 0 then
		ball.x=mid(0+rad,x+(dx/2),127-rad)
		ball.y+=(dy/2)
	else
		ball.x=mid(0+rad,x+dx,127-rad)
		ball.y+=dy
	end
	if ball.x+rad>=127 or ball.x-rad<=0 then
		ball.dx=-dx
		sfx(0)
	end
	if ball.y-rad<=7 then
		ball.dy=-dy
		sfx(0)
	end
	if  ball.y+rad>=131 then
		del(balls, ball)
		sfx(2)
		-- play a sound effect
		if #balls < 1 then
			lose_life()
			shkamnt = 0.4
		else
			shkamnt = 0.15
		end
		combo=1
	end
end

function check_collision(ball, obj_x,obj_y,obj_w,obj_h)
	-- if (ball.y+ball.dy)-rad > obj_y+obj_h then
    --     return false
    -- end
    -- if (ball.y+ball.dy)+rad < obj_y then
    --     return false
    -- end
    --     if (ball.x+ball.dx)-rad > obj_x+obj_w then
    --     return false
    -- end
    -- if (ball.x+ball.dx)+rad < obj_x then
    --     return false
    -- end
    -- return true
	return check_collision2(obj_x,obj_y,obj_w,obj_h,(ball.x+ball.dx)-rad,(ball.y+ball.dy)-rad,rad*2,rad*2)
end

function collision_direction(bx,by,bdx,bdy,tx,ty,tw,th)
	local slp
	if not(bdx==0) then
 		slp = bdy / bdx
 	else
 		slp = nil
 	end
 	local cx, cy
 	if bdx == 0 then
  		return false
 	elseif bdy == 0 then
  		return true
 	elseif slp > 0 and bdx > 0 then
  		cx = tx - bx
  		cy = ty - by
  		return cx > 0 and cy/cx < slp
 	elseif slp < 0 and bdx > 0 then
	 	cx = tx - bx
  		cy = ty + th - by
  		return cx > 0 and cy/cx >= slp
 	elseif slp > 0 and bdx < 0 then
  		cx = tx + tw - bx
  		cy = ty + th - by
  		return cx < 0 and cy/cx <= slp
 	else
 		cx = tx + tw - bx
  		cy = ty - by
  		return cx < 0 and cy/cx >= slp
 	end
end

function change_angle(ball, ang)
	ball.ang=ang
 	if ang==0 then
 		ball.dx=sgn(ball.dx)*1.3
 		ball.dy=sgn(ball.dy)*0.5
	elseif ang==2 then
 		ball.dx=sgn(ball.dx)*0.5
 		ball.dy=sgn(ball.dy)*1.3
	else
 		ball.dx=sgn(ball.dx)
 		ball.dy=sgn(ball.dy)
 	end
end

function newball()
	local b = {
		x     = 0,
		y     = 0,
		dx    = 0,
		dy    = 0,
		ang   = 0,
		stuck = false
	}
	return b
end

function copyball(ball)
	local b = {
		x     = ball.x,
		y     = ball.y,
		dx    = ball.dx,
		dy    = ball.dy,
		ang   = ball.ang,
		stuck = ball.stuck
	}
	return b
end

function releasestuck()
	for ball in all(balls) do
		ball.stuck = false
	end
end

function update_ball(ball)
	if ball.stuck then
		if last_dir=="right" then
			ball.dx=abs(ball.dx)
		else
			ball.dx=-abs(ball.dx)
		end
		ball.x=pad_x+offset
		ball.x=mid(0+rad,ball.x,127-rad)
		if ball.x-pad_x != offset then
			offset = ball.x - pad_x
		end
		ball.y = pad_y - 3
	--	x_prev=x
	--	y_prev=pad_y-3
	else
		
		--check if hit pad
		if check_collision(ball, pad_x,pad_y,pad_w,pad_h) then
			-- check direction
			if collision_direction(ball.x+ball.dx,ball.y+ball.dy,ball.dx,ball.dy,pad_x,pad_y,pad_w,pad_h) then
				ball.dx=-ball.dx
				if ball.x<pad_x+(pad_w/2) then
					ball.x=pad_x-rad
				else
					ball.x=pad_x+pad_w+rad
				end
			else
				ball.dy=-ball.dy
				--bottom
				if ball.y>pad_y then
					ball.y=pad_y+pad_h+rad
				else
				 --top
					ball.y=pad_y-rad
					--change angle
					if abs(pad_dx)>2 then
					 --	flatten angle
						if sgn(pad_dx)==sgn(ball.dx) then
							change_angle(ball, mid(0,ball.ang-1,2))
						else
							--raise angle
							if ball.ang==2 then
								ball.dx=-ball.dx
							else
								change_angle(ball, mid(0,ball.ang+1,2))
							end
						end
					end
				end
			end
			sfx(1)
			combo=1
			if sticky and ball.dy<0 then
				sticky=false
				hasstuck=true
				ball.stuck=true
				ball.x = flr(ball.x)
				offset=ball.x-pad_x
			end
		end
		move_ball(ball)
		for brick in all(bricks) do
			-- check if hit brick
			if not(brick.brk) and check_collision(ball,brick.x,brick.y,brick_w,brick_h) then
				local balldx = ball.dx
				local balldy = ball.dy
			-- no collision if megaball
				if t_mega <= 0 or brick.t=="i" then
				-- check direction
					if collision_direction(ball.x,ball.y,ball.dx,ball.dy,brick.x,brick.y,brick_w,brick_h) then
						ball.dx=-ball.dx
					else
						ball.dy=-ball.dy
					end
				end
				hitbrick(brick, true, balldx, balldy)
				break
			end
		end
		spawntrail(ball.x, ball.y)
	end
end

function multiball()
	--maybe make do random ball to split, only 2 balls, random angle
	if #balls > 2 then
		points+=50
		return
	end
	local brand = rnd(balls)
	local b2 = copyball(brand)
	-- local b3 = copyball(balls[1])
	add(balls, b2)
	-- add(balls, b3)
	if brand.ang == 0 then
		change_angle(b2, 2)
		--change_angle(b3, 2)
	elseif brand.ang == 1 then
		if not brand.stuck then
			change_angle(brand,0)
		end
		change_angle(b2, 2)
		--change_angle(b3, 2)
	else
		change_angle(b2, 0)
		--change_angle(b3, 1)
	end
	b2.stuck = false
end