Glimmr Canvas-Based Drawing

version 2/101030 by Erik Temple

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  • Chapter: Troubleshooting

    Runtime error "cannot divide by zero" (or similar):

        The canvas dimensions have probably not been defined. Be sure you define the canvas before the window-drawing rules are run.

    Inform doesn't recognize the "image-ID" property, or a table in which it is used:

        Inform requires a figure to be defined in the source before it can be referred to. Be sure that your figures are defined in the source *above* the text in which you are attempting to define the associated sprites.

    When I click on a hyperlinked element, the game prints a blank line at the command prompt, and then prints my replacement command:

        This is how Glk is designed; the line space is unavoidable on most interpreters. A new version of the Glk standard will change this, and Glimmr will be updated when this happens. As of this writing, all major Glulx interpreters will respond in this way except for Zoom, which does not insert the extra line. If the line break bothers you, you may want to recommend Zoom to your OS X and Linux players.

    Performance issues:

        Be sure that your images are not too large. Images should be sized no larger than you want them to appear onscreen.

        Note that games played within the Inform IDE will be slower than games played in an external interpreter. The Mac IDE may sometimes show minor scaling artifacts that are not seen with external interpreters. Try pressing the Release button to produce a blorb file, and play that file in the latest version of a fast, modern interpreter.

        If you are using Glimmr debugging, the debugging statements in the routines will slow things down. Turn off Glimmr debugging whenever possible.


    Test your game in all the interpreters you can get your hands on, and recommend the best interpreter(s) to your players. At the time of this writing, Gargoyle and Zoom are both well optimized for graphics and other multimedia effects. Spatterlight on OS X is not, and also has a poor UI for mouse input. Windows Glulxe and Windows Git have a low-resolution timer, and neither is quite as fast with graphic display as Gargoyle, but they should be adequate for most purposes.