refactor

main.lua

@@ -1,25 +1,25 @@
 function love.load()
- b = love.graphics.newImage("Snow_Ball.png")
  b_x, b_y = 100, 100
- b_w, b_h = 36, 36
+ R = 20
 
  v_x, v_y = 0, 0
  love.graphics.setColor(255,255,255)
  love.graphics.setBackgroundColor(0,0,0)
 
  a = 0
  a_k = 500 
+ k_s = 2 -- slingshot strength
 end
 
 function love.draw()
- local x, y = love.mouse.getPosition()
- love.graphics.draw(b, b_x, b_y)
+ love.graphics.circle("fill", b_x, b_y, R)
 
+ local x, y = love.mouse.getPosition()
  if love.mouse.isDown(1) then
  love.graphics.line(x,y,x_press,y_press)
  end
  if love.mouse.isDown(2) then
- love.graphics.line(x,y,b_x+b_w/2,b_y+b_h/2)
+ love.graphics.line(x,y,b_x,b_y)
  end
  love.graphics.print("k="..a_k .." a="..a, 10, 10)
 end
@@ -28,21 +28,16 @@ function love.update(dt)
  local x, y = love.mouse.getPosition()
 
  if love.mouse.isDown(1) then
- b_x = x - b_w / 2
- b_y = y - b_h / 2
- return -- quit function?
+ b_x = x
+ b_y = y
  elseif love.mouse.isDown(2) then
  local t = love.timer.getTime()
  local dx, dy = x - b_x, y - b_y
- local d = norm(dx, dy)
- local d = math.max(d, 10)
- -- local k = 500
- -- a = k * (t - t_start) / (d*d)
- k = 500
+ local d = math.sqrt(dx*dx+dy*dy)
+ local d = math.max(d, R) -- else acceleration gets huge at small distance
  a = a_k / (d*d)
  v_x = v_x + dx/d * a
  v_y = v_y + dy/d * a 
-
  end
 
  b_x = b_x + v_x * dt
@@ -54,23 +49,15 @@ function love.mousepressed(x, y, button, istouch)
  x_press = x
  y_press = y
  end
- if button == 2 then
- t_start = love.timer.getTime()
- end
 end
 
 function love.mousereleased(x, y, button, istouch)
  if button == 1 then
- local k = 1
- v_x = k * (x_press - x)
- v_y = k * (y_press - y)
+ v_x = k_s * (x_press - x)
+ v_y = k_s * (y_press - y)
  end
 end
 
 function love.wheelmoved(x, y)
- a_k = a_k + 20 * y
-end
-
-function norm(x, y)
- return math.sqrt(x*x+y*y)
+ a_k = a_k + a_k / 20 * y -- 5% change
 end