mieki256's diary

_conf.lua

function love.conf(t)
  t.version = "11.3" -- love2d version
  t.window.title = "Arm - love2d"
  t.window.vsync = 1
  t.window.width = 1280
  t.window.height = 720

  -- t.window.fullscreen = true
  -- t.window.fullscreentype = "exclusive"
end

_main.lua

-- Arm on love2d

function love.load()
  love.graphics.setDefaultFilter("nearest", "nearest")

  img = love.graphics.newImage("circle02_64x64_take1_05_5bit32col_edit.png")

  scrw = love.graphics.getWidth()
  scrh = love.graphics.getHeight()
  bx = scrw / 2
  by = scrh / 2

  angles = {}
  pos_buf = {}
  for i = 1, 16 do
    angles[i] = 0
    pos_buf[i] = {bx, by}
  end

  ang = 0
  a0 = 15
  a1 = 30
end

function love.update(dt)
  ang = ang + 90 * dt

  mx, my = love.mouse.getPosition()
  a0 = 45 * (mx - (scrw / 2)) / (scrw / 2)
  a1 = 45 * (my - (scrh / 2)) / (scrh / 2)

  -- angles[1] = 0
  angles[1] = ang

  for i = 2, #angles do
    -- angles[i] = a1 + a1 * math.sin(math.rad(a0 * (i - 2)))
    angles[i] = a1 * math.sin(math.rad(ang * 0.75 + (i - 1) * a0))
  end

  local x = pos_buf[1][1]
  local y = pos_buf[1][2]
  local a = angles[1]

  -- local distance = 30
  local distance = 24 + 12 * math.cos(math.rad(ang * 1.4))

  for i = 2, #angles do
    a = a + angles[i]
    x = x + distance * math.cos(math.rad(a))
    y = y + distance * math.sin(math.rad(a))
    pos_buf[i] = {x, y}
  end
end

function love.draw()
  -- fill window background
  love.graphics.clear(0.4, 0.7, 0.8, 1.0)

  -- draw arm
  local ox, oy = img:getWidth() / 2, img:getHeight() / 2
  love.graphics.setColor(1.0, 1.0, 1.0, 1.0)
  for i = 1, #pos_buf do
    local px = pos_buf[i][1]
    local py = pos_buf[i][2]
    love.graphics.draw(img, px, py, 0, 1.0, 1.0, ox, oy)
  end

  love.graphics.print("a0=" .. tostring(a0), 2, 16)
  love.graphics.print("a1=" .. tostring(a1), 2, 32)

  -- draw FPS txet
  love.graphics.print("FPS: " .. tostring(love.timer.getFPS()), 2, 2)
end

function love.keypressed(key, isrepeat)
  if key == "escape" then
    -- ESC key to exit
    love.event.quit()
  end
end

動作に必要な画像は以下。CC0 / Public Domain ってことで。

_circle02_64x64_take1_05_5bit32col_edit.png

この3つのファイル、conf.lua、main.lua、*.png を適当なフォルダに置いて、「love フォルダ名」で実行できる。

仕組みは…。DXRuby で多関節のソレを書いた際の記事が参考になるはず。アレと同じ仕組みだし。

_mieki256's diary - DXRubyで例の多関節を実験

各関節が角度を持っていて、親の角度＋自分の持ってる角度を使って位置を決めていく、という説明でいいのかな。

余談。class を作って書いたほうがいいのかなと思ったけれど、この程度の処理なら、各関節の角度を保持しておく配列さえあれば動かせるなと思えてきたので、だらだらと書いてしまったり。

_conf.lua

function love.conf(t)
  t.version = "11.3" -- love2d version
  t.window.title = "Cubic bezier - love2d"
  t.window.vsync = 1
  t.window.width = 1280
  t.window.height = 720

  -- t.window.fullscreen = true
  -- t.window.fullscreentype = "exclusive"
end

_main.lua

function get_cubic_bezier_point(p0x, p0y, v0x, v0y, v1x, v1y, p1x, p1y, t)
  local q = 1.0 - t
  local u0 = q * q * q
  local u1 = 3.0 * t * q * q
  local u2 = 3.0 * t * t * q
  local u3 = t * t * t
  local ox = u0 * p0x + u1 * v0x + u2 * v1x + u3 * p1x
  local oy = u0 * p0y + u1 * v0y + u2 * v1y + u3 * p1y
  return ox, oy
end

function love.load()
  love.graphics.setDefaultFilter("nearest", "nearest")

  img = love.graphics.newImage("circle02_64x64_take1_05_5bit32col_edit.png")

  scrw = love.graphics.getWidth()
  scrh = love.graphics.getHeight()
  bx = scrw * 0.95
  by = scrh / 2

  ctrl_points = {
    {100, 200},
    {scrw * 0.3, scrh * 0.1},
    {scrw * 0.6, scrh * 0.9},
    {bx, by}
  }

  points = {}

  ang = 0

  draw_ctrl_points = false
end

function love.update(dt)
  ang = ang + 180 * dt

  -- set control points
  mx, my = love.mouse.getPosition()
  ctrl_points[1][1] = mx
  ctrl_points[1][2] = my

  local a0 = math.sin(math.rad(ang))
  local a1 = math.sin(math.rad(ang * 0.6))

  -- ctrl_points[2][1] = mx + (bx - mx) * 0.3
  ctrl_points[2][2] = scrh * (a0 * 0.5 + 0.5)

  -- ctrl_points[3][1] = mx + (bx - mx) * 0.6
  ctrl_points[3][2] = scrh * (a1 * 0.7 + 0.5)

  -- get cubic bezier points
  local interpolate = 40
  local spd = 1.0 / interpolate
  local p0x, p0y, v0x, v0y, v1x, v1y, p1x, p1y
  p0x = ctrl_points[1][1]
  p0y = ctrl_points[1][2]
  v0x = ctrl_points[2][1]
  v0y = ctrl_points[2][2]
  v1x = ctrl_points[3][1]
  v1y = ctrl_points[3][2]
  p1x = ctrl_points[4][1]
  p1y = ctrl_points[4][2]

  points = {}
  local t, x, y
  for t = 0, 1.0, spd do
    x, y = get_cubic_bezier_point(p0x, p0y, v0x, v0y, v1x, v1y, p1x, p1y, t)
    points[#points + 1] = {x, y}
  end
  t = 1.0
  x, y = get_cubic_bezier_point(p0x, p0y, v0x, v0y, v1x, v1y, p1x, p1y, t)
  points[#points + 1] = {x, y}
end

function love.draw()
  -- fill window background
  love.graphics.clear(0.2, 0.5, 0.6, 1.0)

  -- draw arm
  local ox, oy = img:getWidth() / 2, img:getHeight() / 2
  love.graphics.setColor(1.0, 1.0, 1.0, 1.0)
  for i = #points, 1, -1 do
    local px = points[i][1]
    local py = points[i][2]
    love.graphics.draw(img, px, py, 0, 1.0, 1.0, ox, oy)
  end

  -- draw control points line
  if draw_ctrl_points then
    love.graphics.setColor(1.0, 1.0, 1.0, 0.7)
    love.graphics.line(
      ctrl_points[1][1],
      ctrl_points[1][2],
      ctrl_points[2][1],
      ctrl_points[2][2],
      ctrl_points[3][1],
      ctrl_points[3][2],
      ctrl_points[4][1],
      ctrl_points[4][2]
    )
    for i = 1, 4 do
      local px, py
      px = ctrl_points[i][1]
      py = ctrl_points[i][2]
      love.graphics.circle("line", px, py, 16)
    end
  end

  -- draw FPS
  love.graphics.setColor(1.0, 1.0, 1.0, 1.0)
  love.graphics.print("FPS: " .. tostring(love.timer.getFPS()), 2, 2)
  love.graphics.print("C key : Draw control points", 2, 20)
end

function love.keypressed(key, isrepeat)
  if key == "escape" then
    -- ESC key to exit
    love.event.quit()
  elseif key == "c" then
    draw_ctrl_points = not (draw_ctrl_points)
  end
end

動作に必要な画像は以下。CC0 / Public Domain ってことで。

_circle02_64x64_take1_05_5bit32col_edit.png

conf.lua、main.lua、*.png を適当なフォルダに置いて、「love フォルダ名」で実行できる。

余談。昔のCPUは、掛け算(乗算)を使うとクロック数が増えるし、固定小数点で演算してたので桁合わせが面倒だしで、掛け算を使いまくりのこういった処理は、ちと気分的に避けがちだったのだけど。今のCPUなら楽勝だろうなあ、と思ったので試しに書いてみたり。滑らかに動いてるし、さすがに全然余裕ですな…。