I am brand new to Codea and halfway through my tutorials and they are enlightening and I can’t wait to get stuck in, but just wanted to enquire whether it is possible to touch and drag objects from one point to another and if so, is there existing code or tutorials based on this specifically?
thanks
You could make the X and Y of a sprite touch.x and touch.y
Example:
function draw()
sprite("SpaceCute:Background",touch.x,touch.y)
Quick example using a class (so you can make multiple instances)
--# Main
function setup()
exobj = Object(WIDTH/2, HEIGHT/2)
end
function draw()
background(40, 40, 50)
exobj:draw()
end
function touched(touch)
exobj:touched(touch)
end
--# Object
Object = class()
function Object:init(x,y)
self.pos = vec2(x, y)
self.selected = false
self.size = 100
end
function Object:draw()
rectMode(CENTER)
fill(255, 141, 0, 255)
rect(self.pos.x, self.pos.y, self.size, self.size)
end
function Object:touched(touch)
if touch.state == BEGAN then
-- If you touch the object, select it
if touch.x > self.pos.x - self.size/2 and touch.x < self.pos.x + self.size/2 and
touch.y > self.pos.y - self.size/2 and touch.y < self.pos.y + self.size/2 then
self.selected = true
end
-- Center on touch
if self.selected then
self.pos = vec2(touch.x, touch.y)
end
elseif touch.state == MOVING then
-- If the object is selected, follow the touch
if self.selected then
self.pos = vec2(touch.x, touch.y)
end
elseif touch.state == ENDED then
-- When you let go, deselect the object
self.selected = false
end
end
@jamesfootlight Here’s another example. Just select a character and drag it around.
displayMode(FULLSCREEN)
function setup()
selected=0
ex=390 -- ellipse x
ey=410 -- ellipse y
ea=200 -- ellipse a radius
eb=100 -- ellipse y radius
rx=70
ry=120
rw=630
rh=580
tab={}
for z=1,5 do -- create 5 objects
table.insert(tab,vec2(math.random(70,700),math.random(120,700)))
end
tab1={} -- table of sprites
table.insert(tab1,readImage("Planet Cute:Character Boy"))
table.insert(tab1,readImage("Planet Cute:Character Horn Girl"))
table.insert(tab1,readImage("Planet Cute:Character Cat Girl"))
table.insert(tab1,readImage("Planet Cute:Character Pink Girl"))
table.insert(tab1,readImage("Planet Cute:Character Princess Girl"))
end
function draw()
background(40, 40, 50)
noFill()
stroke(255)
strokeWidth(2)
rect(rx,ry,rw,rh)
ellipse(ex,ey,ea*2,eb*2) -- draw ellipse
for a,b in pairs(tab) do -- draw each objects
if checkEllipse(b.x,b.y) then
sprite("Planet Cute:Heart",b.x,b.y)
else
sprite(tab1[a],b.x,b.y)
end
end
end
function checkRect(x,y)
if x>rx and x<rx+rw and y>ry and y<ry+rh then
return true
end
return false
end
function checkEllipse(x,y)
-- determine if touched value is inside ellipse
if (x-ex)^2/ea^2+(y-ey)^2/eb^2 <= 1 then
return true
end
return false
end
function touched(t)
if t.state==BEGAN then -- check which object is selected
v1=vec2(t.x,t.y)
for a,b in pairs(tab) do
if v1:dist(vec2(b.x,b.y))<50 then
selected=a
break
end
end
end
if t.state==MOVING and selected>0 then -- move selected object
if checkRect(t.x,t.y) then
tab[selected].x=t.x
tab[selected].y=t.y
end
end
if t.state==ENDED then -- done moving
selected=0
end
end
You guys are amazing, it works like a dream. Following this up, does anyone know if it’s possible for an image to react at different points on the screen? Eg if there were 4 quadrants on a page and if u moved an object into this quadrant or area could a command come up on the screen or the movable object change opacity ?
@jamesfootlight Yes. You would just have to compare the x,y value of what you’re moving. If it’s in a special area, then you do something special.
@jamesfootlight I changed my above code. See if that’s what you’re thinking of. Move the character into the rectangle.
@jamesfootlight - this formula will tell you which quadrant you are in, numbered 1 to 4 ( I’ll leave it to you to work out which is which)
q = math.floor(x*2/WIDTH)*2+math.floor(y*2/HEIGHT) +1
Excellent, thanks. If I wanted 5 different objects that all had seperate images, would i reference them in the function draw() section? ie sprite1 etc?
yes, but if you don’t know this, then I suggest you may be getting a bit ahead of yourself.
I suggest you stick with the tutorials until you have the basics of putting stuff on the screen, so you don’t ask unnecessarily basic questions. It’s not that we mind helping, but we prefer to fix problems than provide personal tuition 
Of course, thanks, I completely appreciatte that. I will keep on working on my code and learn some more! thanks
So, i’m almost there with my objects on my new background, however, i need them to react within an ellipse area in the centre of my screen, i have adapted the code below to try to get them to react to an ellipse area but to no avail, i keep getting an error message ‘then’ expected near’,', can anyone help?
displayMode(FULLSCREEN)
function setup()
tab={}
for z=1,5 do -- create 5 objects
table.insert(tab,vec2(math.random(WIDTH),math.random(HEIGHT)))
end
end
function draw()
background(40, 40, 50)
ellipse(390,410,0,0)
for a,b in pairs(tab) do -- draw each objects
if b.x<390,410 and b.y<390,410 then
sprite("Planet Cute:Character Princess Girl",b.x,b.y)
else
sprite("Planet Cute:Character Boy",b.x,b.y)
end
end
end
function touched(t)
if t.state==BEGAN then -- check which object is selected
v1=vec2(t.x,t.y)
for a,b in pairs(tab) do
if v1:dist(vec2(b.x,b.y))<50 then
selected=a
break
end
end
end
if t.state==MOVING and selected>0 then -- move selected object
tab[selected].x=t.x
tab[selected].y=t.y
end
if t.state==ENDED then -- done moving
selected=0
end
end
@jamesfootlight - first, put three ~ at the top and bottom of your code to format it nicely. (I fixed it for you).
The problem is probably with
If b.x<390,410
What is the comma and the 410 doing there? They will cause an error (and so will the y value later on that line).
Other than that, your code looks pretty good.
Thanks, the problem i have is I need the sprites to change when they enter/leave the ellipse and they are currently only changing in the bottom left of the screen.
and the 390,410 (I originally had if b.x<ellipse and b.y<ellipse then
but this caused an error
ignatz thanks again,and dave1707 I’m sending you digital hugs!
my interactive risk map is now really taking shape thanks to all your help, I now need to ensure my objects cannot be moved out of a rectangle (70,120,630,580) that sits just outside the ellipse, would I first of all code the rectangle in function set up():
rx=70
ry=120
rw=630
rh=580
then in function draw():
rect(rx,ry,rw,rh)
fill (0,0,0,0)
then do function checkSprite ()
if b.x,b.y-sprite<rw or b.x,b.y+sprite >rw then stop
if b.x,b.y-sprite<rh or b.x,b.y+sprite >rh then stop
My ipad just ran out of juice so unable to check till later, but is this the right direction?
thanks guys!
@jamesfootlight Here’s a routine you could use. Just call checkRect with the x,y values of the sprites. If you get stuck, see my code above. I added it there.
function checkRect(x,y)
if x>rx and x<rx+rw and y>ry and y<ry+rh then
return true
end
return false
end
@jamesfootlight. you are in the community. (CC)??
in the community there are many examples that you can download and you can provide enough support.
Also u can see the Wikis created by @ignatz
Thanks Luismi, in the below code, how would i attribute each image in the table to change into an individual image, rather than each one changing into the heart?
ie each image changes into a different image when entering the ellipse?
function setup()
selected=0
ex=390 -- ellipse x
ey=410 -- ellipse y
ea=200 -- ellipse a radius
eb=100 -- ellipse y radius
rx=70
ry=120
rw=630
rh=580
tab={}
for z=1,5 do -- create 5 objects
table.insert(tab,vec2(math.random(70,700),math.random(120,700)))
end
tab1={} -- table of sprites
table.insert(tab1,readImage("Planet Cute:Character Boy"))
table.insert(tab1,readImage("Planet Cute:Character Horn Girl"))
table.insert(tab1,readImage("Planet Cute:Character Cat Girl"))
table.insert(tab1,readImage("Planet Cute:Character Pink Girl"))
table.insert(tab1,readImage("Planet Cute:Character Princess Girl"))
end
function draw()
background(40, 40, 50)
noFill()
stroke(255)
strokeWidth(2)
rect(rx,ry,rw,rh)
ellipse(ex,ey,ea*2,eb*2) -- draw ellipse
for a,b in pairs(tab) do -- draw each objects
if checkEllipse(b.x,b.y) then
sprite("Planet Cute:Heart",b.x,b.y)
else
sprite(tab1[a],b.x,b.y)
end
end
end
function checkRect(x,y)
if x>rx and x<rx+rw and y>ry and y<ry+rh then
return true
end
return false
end
function checkEllipse(x,y)
-- determine if touched value is inside ellipse
if (x-ex)^2/ea^2+(y-ey)^2/eb^2 <= 1 then
return true
end
return false
end
function touched(t)
if t.state==BEGAN then -- check which object is selected
v1=vec2(t.x,t.y)
for a,b in pairs(tab) do
if v1:dist(vec2(b.x,b.y))<50 then
selected=a
break
end
end
end
if t.state==MOVING and selected>0 then -- move selected object
if checkRect(t.x,t.y) then
tab[selected].x=t.x
tab[selected].y=t.y
end
end
if t.state==ENDED then -- done moving
selected=0
end
end