tween() is a new feature in Codea version 1.5 that facilitates animation. The code below allows the form of the built-in easing functions to be explored, and illustrates the use of a custom easing function (myEasing(t, b, c, d)).
The code also uses the callback argument of the parameter.boolean() and parameter.integer() functions.
--
-- Tween Explorer
--
-- A custom easing function
-- t is the current time
-- d is the duration of the animation
-- b is the initial animated value
-- c is the change in the animated value by the end of the animation
function myEasing(t, b, c, d)
t = t / d
return b + c * math.pow(math.sin(t * math.pi * 2.5), 2)
end
supportedOrientations(LANDSCAPE_ANY)
function setup()
easingType = {
"quad", "cubic", "quart", "quint",
"expo", "sine",
"circ", -- Undocumented in Codea 1.5(16)
"back", "bounce", "elastic"}
inOutType = {"In", "Out", "InOut", "OutIn"}
duration = 3
dim = math.min(WIDTH, HEIGHT)
offset = dim / 4
margin = dim / 20
width = margin / 10
dim = dim - offset * 2 - margin - width
easingFunction = 1
inOutFunction = 1
parameter.boolean("isCustomEasingFunction", true, reset)
parameter.integer("easingFunction", 1, #easingType, 1,
resetEF)
parameter.watch("easingType[easingFunction]")
parameter.integer("inOutFunction", 1, #inOutType, 1, resetEF)
parameter.watch("inOutType[inOutFunction]")
local col = color(255, 255, 0)
fill(col)
stroke(col.r * 0.5, col.g * 0.5, col.b * 0.5)
rectMode(CORNER)
spriteMode(CORNER)
ellipseMode(CORNER)
fontSize(32)
end
function draw()
background(64)
text(easingString..": touch Viewer to rerun.",
WIDTH / 2, HEIGHT - 50)
strokeWidth(5)
line(offset, offset + margin,
offset + margin + dim + width, offset + margin)
line(offset + margin, offset,
offset + margin, offset + margin + dim + width)
noStroke()
rect(offset, subjectY.y + offset + margin, margin, width)
rect(subjectX.x + offset + margin, offset, width, margin)
setContext(img)
ellipse(subjectX.x, subjectY.y + offset + margin, width)
setContext()
sprite(img, offset + margin, 1)
end
function touched(touch)
if touch.state == BEGAN then reset() end
end
function resetEF()
if isCustomEasingFunction then return end
reset()
end
function reset()
img = image(dim + width, dim + width + offset * 2)
subjectX = {x = 1}
local targetX = {x = dim}
tween(duration, subjectX, targetX)
subjectY = {y = 1}
local targetY = {y = dim}
if isCustomEasingFunction then
easingString = "myEasing"
tweenId = tween(duration, subjectY, targetY, myEasing)
else
easingString = easingType[easingFunction]..
inOutType[inOutFunction]
tweenId = tween(duration, subjectY, targetY, easingString)
end
end