The API itself is often times made as simple as possible. Images are referred by their string names, and the API handles the loading part. You just draw with it! Touch information is stored in a global variable for easy polling. The game loop is already set up. And there are plenty of utility shape drawing functions.
The downside is that the API is too simple at times - I could overlook this if the app didn't claim to provide an environment enabling a person to make completely polished games for the App Store. The simple API is great for prototyping simple interactions.
Consider the simple task of a button. A button is ubiquitous, it should handle presses and provide appropriate feedback. Many of the more complex examples shipped with Codea use a button, yet each has its own abstraction. Spiritely, the pixel art tool, goes just as far as to try to replicate the native iOS feel. But that is difficult...
Let me explain, when a button is pressed, a typical UI will make it give user feedback. Like get darker, bevel in, etc. If the finger wanders off the button, but not off the touchscreen, then no other button should provide feedback. Imagine that where the finger goes down on a button, all events go back to that button. Such a feature requires planning, and above all simply reimplementing what's been already done a million times.
Yes, there are multiple interaction paradigms. The home screen on iOS uses the one described above.
In the end, if I were creating just the game scene on pong, then Codea would be perfect. If I wanted menus and more, then maybe I'd want something similar to a rudimentary GUI framework. Which I provide below.
One last note, the tabs are executed in order. So a super class should appear before any inheriting classes in the tabs.
In the end, I recommend Codea for prototyping on the go. Have an idea for something? Prototype quickly and show it to people right then and there. No need to lug a mac to fine tune interactions in a game prototype. It's kind of nice that way,
Below are a series of objects to use in Codea that may prove useful for UI work. It's in progress, but starting to make my development easier (I'm slowly progressing on it):
XControl = class()
function XControl:init(position, size)
self.position = position
self.size = size
self.parent = nil
self.children = {}
self.onDraw = {}
self.pvtxc = {}
end
function XControl:pvtDraw()
self:draw()
for i,v in ipairs(self.children)
do
pushMatrix()
translate(self.position.x, self.position.y)
v:pvtDraw()
for ind, drw in ipairs(self.onDraw)
do
drw(self)
end
popMatrix()
end
end
function XControl:addDrawFn(fn)
local l = #self.onDraw
self.onDraw[l] = fn
end
function XControl:draw()
end
function XControl:addChild(inChild)
inChild:removeFromParent()
local cid = #(self.children)+1
self.children[cid] = inChild
inChild.parent = self
inChild.pvtxc.childId = cid
end
function XControl:removeFromParent()
if self.parent == nil
then
return
end
local pcid = table.getn(self.parent.children)
if self.parent.pvtxc.count ~= 1 then
self.parent.children[self.pvtxc.childId]
= self.parent.children[pcid]
self.parent.children[self.pvtxc.childId].pvtxc.childId
= self.pvtxc.childId
end
table.remove(self.parent.children)
end
function XControl:pvtGetTouchedControl(pt)
for i,v in ipairs(self.children)
do
if v:isWorldPointWithin(pt)
then
return v:pvtGetTouchedControl(pt)
end
end
return self
end
function XControl:isPointWithin(pt)
return (pt.x >= 0 and pt.y >= 0
and pt.x <= self.size.x
and pt.y <= self.size.y)
end
function XControl:isWorldPointWithin(pt)
return self:isPointWithin(self:world2local(pt))
end
function XControl:isTouchWithin(touch)
return self:isWorldPointWithin(vec2(touch.x, touch.y))
end
function XControl:local2world(v2)
if self.parent == nil
then
return v2 + self.position
else
return self.parent:local2world(v2 + self.position)
end
end
function XControl:world2local(v2)
if self.parent == nil
then
return v2-self.position
else
return self.parent:local2world(v2 - self.position)
end
end
function XControl:pvtOnTouched(touch)
end
And for a button...
XButton = class(XControl)
function XButton:init(position, size)
XControl.init(self, position, size)
self.onPress = nil
self.onRelease = nil
self.onDrag = nil
self.onTouch = nil
end
function XButton:pvtOnTouched(touch)
if touch.state == BEGAN and self.onPress ~= nil
then
self.onPress(touch)
end
if touch.state == MOVING and self.onDrag ~= nil
then
self.onDrag(touch)
end
if touch.state == ENDED
then
if self.onRelease ~= nil
then
self.onRelease(touch)
end
if self:isTouchWithin(touch) and self.onTouch ~= nil
then
self.onTouch(touch)
end
end
end
