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I'm making an Asteroids clone in Haskell using Gloss.

I want the spaceship to come back from the left if it goes out on the right side of the screen. This is made unnecessarily tricky by the fact that the origin (0, 0) is in the middle of the screen.

Is there a way to move the origin to the top (or bottom) left?

My Main module (where I'm interacting with Gloss) looks like this:

module Main where

import           Graphics.Gloss    (Display (InWindow), black, play)

-- my own imported code
import           Assets            (loadAssets)
import           GameState         (defaultHeight, defaultWidth, initGameState)
import           HandleInput       (handleInput)
import           ProgressGameState (progressGameState)
import           Render            (render)

windowDisplay :: Display
windowDisplay = InWindow "Window" (defaultWidth, defaultHeight) (10, 10)

main :: IO ()
main = do
  assets <- loadAssets
  play
    windowDisplay
    black
    60
    initGameState
    (render assets)
    handleInput
    progressGameState
The Hoff
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1 Answers1

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I don't think there's an easy way to move the origin. But the conversion between whatever your format is a simple translation. You can use a function (or even a smart constructor) to do the calculation between the two.

For example, if (0,0) is at the center of a picture with the dimensions (x,y), but you would want it to be at the top left, all you have to do is substract (x/2,y/2) from all your points to make the math right again.

jbetzend
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