Drawing basics

The Lua scripting language allows you to give your plugin more advanced features.

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Ølsken
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Drawing basics

#1

Post by Ølsken » Sun Apr 12, 2020 12:58

Introduction
Have you ever wanted to draw some image or text onto your screen?
If that's the case you came to the right place as I will tech you how to use drawing functions in Lua!
This tutorial is written for people who are familiar with JSON, if you are not I would highly recommend learning that first!
I made sure to include as much examples to make it easy to understand.
Any code in this tutorial is allowed to use without permission.

Getting started
Before you can start drawing images do a few things.
First you have to include a Lua script into your JSON file which can be done quite simply:

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[{
"id":"$drawing_tutorial",
"type":"script",
"script":"tutorial.lua"
}]
Now open your Lua script in my case it would be "tutorial.lua".
Now you have to write the following inside the Lua script:

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function script:update()
  stuff
end
I will breakdown what all of this means.
function -> Block of code that will be run when called
script:update -> Will tell TheoTown when to call the function (more information in Drawing methods)
stuff -> Not actual code; just a placeholder
end -> End the function

Drawing methods
There are 2 ways of drawing images or text on your screen:
script:update vs script:overlay
the difference would be:
script:update
  • Will only be drawn when in a city.
  • Draws under game UI.
script:overlay
  • Will always be drawn whether in a city or not.
  • Draws over game UI.
Drawing text
This is the simplest drawing function since you don't need anything to use it.

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Drawing.drawText(text,x,y,fontSize)
If you understand JSON you can think of it like:

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//JSON format
"Drawing":[
  "drawText":{"text":text, "x":x, "y":y, "size":fontSize}
]
Unlike JSON you have to remember the order since it doesn't tell you what value goes where, but you can write it much more faster.
So for example if you write:

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function script:update()
  Drawing.drawText("Hello Lua!",100,100)
end
This draws the text "Hello Lua!" at x = 100 and y = 100!
2020-04-12.png
Now if you want to play around with font size you can put one of these in fontSize

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TheoTown.RESOURCES.skin.fontSmall
TheoTown.RESOURCES.skin.fontDefault   -- This one will be used by default
TheoTown.RESOURCES.skin.fontBig

--example:
Drawing.drawText("Hello Lua!",100,100,TheoTown.RESOURCES.skin.fontBig) --This will draw "Hello Lua!" but bigger!
Drawing images
Drawing images will require a little bit more work than text, but it's definitely more fun!
Let's say you wanted to draw this image of a bear.
art.png
art.png (1.07 KiB) Viewed 436 times
First you would need to add an image as a form of an animation in your JSON file:

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[{
"id":"$drawing_tutorial",
"type":"script",
"script":"tutorial.lua"
},{
  "id":"$art_bear", //the image to display
  "type":"animation",
  "frames":[{"bmp":"art.png"}]
}]
Now you will need to load your image as a draft in Lua.
Simply put a draft is a JSON object like a building or in this case an animation.
You have to load it in to use it inside a Lua script.

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name = Draft.getDraft(id):getFrame(frameNumber)
Since you load a animation, which can have multiple frame you must specify the frame you want to display with getFrame()
as it can only display one frame at a time, Drawing animations with multiple frames are possible but
a little complicated so it won't be in this tutorial.

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function script:init()
  image = Draft.getDraft("$art_bear"):getFrame(1) 	--Do not forget the getFrame(1). Common error for me :P
end
script:init will be called when the game is initializing (loading). You have to load in drafts during initialization or you can't use them in
other game stages.
If you don't know what "image" is, it is a variable that holds the draft that we loaded.
Now let's use the image drawing function:

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Drawing.drawImage(draft,x,y)
Adding it in our code will look like:

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function script:init()
  image = Draft.getDraft("$art_bear"):getFrame(1)
end

function script:update()
  Drawing.drawText("Hello Lua!",100,100)
  Drawing.drawImage(image,200,100)
end
2020-04-12 (10).png
Set drawing color, opacity etc...
Plain text is boring, let's spice things up by adding some color to it using setColor():

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Drawing.setColor(r,g,b)

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function script:init()
  image = Draft.getDraft("$art_bear"):getFrame(1)
end

function script:update()
  Drawing.setColor(0,255,0)	--Make it green to make me look like I know what I am doing!
  Drawing.drawText("Hello Lua!",100,100)
  Drawing.drawImage(image,200,100)
end
2020-04-12 (12).png
As you can see that the color applied on everything.
The reason why is that setColor() applies to everything under it, so to fix that you need to use:

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Drawing.reset()

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  ...
  Drawing.setColor(0,255,0)	--Make it green to make me look like I know what I am doing!
  Drawing.setAlpha(0.5)	--lets also set the opacity to 50%
  Drawing.drawText("Hello Lua!",100,100)
  Drawing.reset()	--This should isolate setColor() to drawText() only
  ...
2020-04-12 (15).png
Examples
If you prefer learning by looking or playing around with examples I have a few for you:
Show
move imitation
If you want to imitate the move BBCode in TheoTown this is the code for that:
:lua:

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function script:init()
  image = Draft.getDraft("$art_bear"):getFrame(1)
end

local x = 0
local imageWidth = 44
local speed = 3

function move()
  x = x - speed
  if x <= imageWidth * -1 then
    x = select(1,Drawing.getSize())
  end
  return x
end

function script:update()
  Drawing.drawImage(image,move(),200)
end
Show
blinking images
This will create a blinking image that will appear and then disappear in random places

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function script:init()
  image = Draft.getDraft("$art_bear"):getFrame(1)
end

local opacity = 0
local width,height = Drawing.getSize()
local x = 0
local y = 0
local factor = -0.1 --speed
local imageWidth = 44
local imageHeight = 35

function script:update()
  if opacity <= 0 then
    math.randomseed(os.time())
    x = math.random(0,width - 1 - imageWidth)
    y = math.random(0,height - 1 - imageHeight)
    factor = factor * -1
  elseif opacity >= 1 then 
    factor = factor * -1
  end
  Drawing.setAlpha(opacity)
  opacity = opacity + factor
  Drawing.drawImage(image,x,y)
end
ImageJust my opinion

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Re: Drawing basics

#2

Post by JustAnyone » Sun Apr 12, 2020 13:46


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Re: Drawing basics

#3

Post by KINGTUT10101 » Sun Apr 12, 2020 18:15

Do these images and text scale and move with changes in resolution?

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Re: Drawing basics

#4

Post by KINGTUT10101 » Sun Apr 12, 2020 18:18

Also, is it possible to make these tiles interactable? I would like to detect when a user taps on a picture, if possible.

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Re: Drawing basics

#5

Post by Ølsken » Sun Apr 12, 2020 21:55

KINGTUT10101 wrote:
Sun Apr 12, 2020 18:18
Also, is it possible to make these tiles interactable? I would like to detect when a user taps on a picture, if possible.
I would just do it as:

Code: Select all

function script:update()
  Drawing.drawImage(draft,imageX,imageY)
end

function script:tap(tx,ty,x,y)
  if x >= imageX and x <= imageX + imageWidth and y >= imageY and y <= imageY + imageHeight then
    --something
    return false
  end
end
return false is to prevent game stuff from activating when clicking on the screen. For example, if you had a building behind the image and you clicked on the image the building info will pop up return false prevents that.
ImageJust my opinion

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Re: Drawing basics

#6

Post by Ølsken » Sun Apr 12, 2020 21:57

KINGTUT10101 wrote:
Sun Apr 12, 2020 18:15
Do these images and text scale and move with changes in resolution?
Yes
ImageJust my opinion

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Re: Drawing basics

#7

Post by KINGTUT10101 » Sun Apr 12, 2020 22:02

Thank you. This explains a lot. I'll try looking into this for my prison plug-in.

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Re: Drawing basics

#8

Post by BLUEISH27 » Sun May 17, 2020 17:54

Well It doesnt work on me Why ?

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Re: Drawing basics

#9

Post by Ølsken » Tue May 19, 2020 10:02

BLUEISH27 wrote:
Sun May 17, 2020 17:54
Well It doesnt work on me Why ?
Hmm, you need to be more specific for me to help.
Provide me the code and I can take a look. ;)
ImageJust my opinion

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Re: Drawing basics

#10

Post by BLUEISH27 » Mon May 25, 2020 9:59

Ølsken wrote:
Tue May 19, 2020 10:02
BLUEISH27 wrote:
Sun May 17, 2020 17:54
Well It doesnt work on me Why ?
Hmm, you need to be more specific for me to help.
Provide me the code and I can take a look. ;)
Luckily it works

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