function lerp(a, b, c)
  return a + (b - a) * c
end

function dlerp(a, b, c)
  return lerp(b, a, 0.5^c)
end

function bton(bool)
  return bool and 1 or 0
end

function try(fn, ...)
  if fn then
    fn(...)
  end
end

function min(a, b)
  if a < b then
    return a
  end
  return b
end

function normalize(x, y)
  if x == 0 and y == 0 then
    return 0, 0
  end

  local leng = math.sqrt(x*x + y*y)
  return x / leng, y / leng
end

-- Top left corner
function point_in_rect(px, py, rx, ry, rw, rh)
  return px > rx and px < rx + rw and py > ry and py < ry + rh
end

function dist(x1, y1, x2, y2)
  local dx = x1 - x2
  local dy = y1 - y2
  return (dx*dx + dy*dy)^0.5
end

function sign(x)
  if x == 0 then
    return 0
  end
  return x < 0 and -1 or 1
end

function round(x)
  return math.floor(x + 0.5)
end

function clamp(a, min, max)
  return math.min(max, math.max(a, min))
end

function snap(x, step)
  return round(x / step) * step
end

function frac(x)
  return x - math.floor(x)
end

local function angle_diff(a, b)
  local diff = (b - a) % (math.pi * 2)
  return (2 * diff) % (math.pi * 2) - diff
end

function lerp_angle(a, b, t)
  return a + angle_diff(a, b) * (1 - 0.5^t)
end

function dot(x, y, xx, yy)
  return x*xx + y*yy
end

function vec_sqlen(x, y)
  return x*x + y*y
end

function vec_len(x, y)
  return math.sqrt(x*x + y*y)
end

function rotate_vec(x, y, r)
  local angle = math.atan2(y, x) + r
  local len = mathx.vec_len(x, y)
  return math.cos(angle) * len, math.sin(angle) * len
end

function table.shallow_copy(t)
  local t2 = {}
  for k,v in pairs(t) do
    t2[k] = v
  end
  return t2
end