Line inside setcontext crashes codea

Comments

• dave1707 Mod

  December 2021 Posts: 10,049

  @Pakz Not sure what you’re trying to do, but here’s how you might use set context.

  To post code, put 3 tildes ~~~ on a line before and after your code.

  Without seeing your complete code I can’t say why you were crashing. The above code didn’t crash my iPad.

  viewer.mode=FULLSCREEN
  
  function setup()
      im = image(64,64)
      setContext(im)
      stroke(255)
      strokeWidth(2)
      for x=0,64 do
          line(x,x/2,x,x/2)
          --rect(64-x,32-x/2,1,x)
      end
      setContext()
  end
  
  function draw()
      background(255, 190, 0)
      sprite(im,WIDTH/2,HEIGHT/2)
  end
  
• Pakz

  December 2021 Posts: 20

  Ah. When I put the code with the line command inside the setup function it does not crash. When outside that function(I put it outside a function on the top of the code) it does crash with the line command but not with the rect command.

  I think I need to start putting code like that inside setup()
• dave1707 Mod

  December 2021 edited December 2021 Posts: 10,049

  @Pakz Normally all of your code should be within a function, but with a few exceptions. The setup function needs to run first because there’s a lot things that needs to be initialized so the code runs right.
• Pakz

  December 2021 Posts: 20

  That makes sense and wil make sure to start putting most things inside functions now. I was a bit worried it just exited there.
• John Admin Mod

  December 2021 Posts: 787

  Before setup is called the graphics context hasn't been set up yet. Code outside of a function gets called first, so this is why you get issues with calls to graphics based functions
• RonJeffries Mod

  December 2021 edited December 2021 Posts: 1,364

  I might add that there are other issues with code outside of functions, some of which can be really confusing. It can be a pain, but I've come to think that what works best for me is to do one of two things:

  First, most commonly, I'll put initialization code in setup, or a function called from setup. This is a bit of a pain, because often I forget, and it makes exporting the code more difficult, as the receiving program needs to do the setup stuff.

  Second, I might use a "lazy init", some code like this, in code that needs initialization, such as a class Foo. (The "init" below is the one that defines an instance when you say. Foo().

  function Foo:init()
      if not FooInitialized then
          do the initialization here
          FooInitialized = true
      end
  end
  

  There are, of course, more "clever" ways to do this sort of thing but these two approaches are my most common.

  I was just bitten by the "init outside of a function" problem yesterday, so it still happens. I was so sure that this one was OK ...
• John Admin Mod

  December 2021 Posts: 787

  Yeah I can see how this is a pain. The new runtime I'm working on allows you to do anything you want outside of setup, so you can even load images, create shaders, etc. I haven't tested contexts in that way though.