pico8 utils

collision.p8

--[[ collision detection ]]--

-- point inside the rectangle
function is_point_in_rect(x,y,left,top,right,bottom)
  return top<y and y<bottom and left<x and x<right
end

function lines_overlapping(min1, max1, min2, max2)
  return min1>min2 and max2>min1
end

-- rectangles overlapping
function rects_overlapping(left1,top1,right1,bottom1,left2,top2,right2,bottom2)
  return lines_overlapping(left1, right1, left2, right2) and 
    lines_overlapping(top1,bottom1,top2,bottom2)
end

-- distance between circle points smaller than sum of diameters
functions circles_overlapping(x1,y1,r1,x2,y2,r2)
  -- sqrt(dx^2+dy^2)<r1+r2
  local dx=mid(-128,x2-x1,128)
	local dy=min(-128,y2-y1,128)
  return dx*dx+dy*dy<(r1+r2)*(r1+r2)
end

state.p8

game = {
  started = false,
  update = function(self)
    self.state.update()
  end,
  change_state = function(self, state)
    self.state = state
    state:update()
  end,
}
started = {
 game = game,
 update = function(self)
   game.started = true
 end
}
stopped = {
  game = game,
  update = function(self)
    game.started = false
  end
}

game:change_state(started)
game:draw()
game:change_state(stopped)
game:draw()