Debugging an application or screensaver.

DemoGL normally doesn't log that much information when starting up or when some event occurs. This can be switched off by setting the quickboot variable, DGL_VF_QUICKBOOT, to false, using DEMOGL_SetVariable. The bootphase of an application will take longer on slow machines but a lot more information is logged on the console. Also when TLE's are executed or other events occur, they are logged on the console. Errors are always logged on the console, with or without having DGL_VF_QUICKBOOT set to false.

From application code, developers can log runtime information on the console by calling DEMOGL_ConsoleLogLine or it's variable argument variant: DEMOGL_ConsoleLogLineV. DEMOGL_ConsoleLogLine is a little faster than DEMOGL_ConsoleLogLineV, but has the single string restriction. DEMOGL_ConsoleLogLineV works as printf and is a very flexible solution to log runtime variable contents.

Set the console buffer size to a large number. Default the buffer contains 500 lines, but DemoGL logs a lot of info so consider if that is enough. If not, change it with DEMOGL_ConsoleSetAppearance where you can also change the number of lines in the debug overlay.

Use the keys F2-F7 to list information about the current running application. To show the real frames per second, press F2 to enable that overlay. You can also enable that overlay by default by setting DGL_VF_SHOWFPS to true. To show the list of currently created layers, visible and hidden, plus the effects on those layers, press F3. This can be handy when effects dissapear while they shouldn't: an effectobject is started on a layer that contained already an effect. Press F4 to list all registered effects with their names known by DemoGL. This is important because objectnames are case sensitive. If TLE's don't behave as planned, use F7 to list the current timeline and all TLE's on it, if they're executed, the current timespot on the timeline, all TLE's commands, objectnames and parameters.

To start and stop effects during runtime, use the input prompt. This prompt can be enabled by enabling the debug overlay by pressing F5 first and then enable the input prompt by pressing F6. To execute a TLE, simply type it on the input prompt with out the timespot parameter and press ENTER. The TLE will be executed immediately. This way, the designer can test which effects to place on which layers and if the developer has added variable support to the Receive*() methods in the effectclasses, the designer can send parameters to the effects at runtime to check and test what is best.

When developing a screensaver, it's wise to first build it as a normal application, so it won't exit when a key is pressed. Then when it runs ok, it can be modified to act as a screensaver. Because DemoGL will take care of all the screensaver specific stuff, your application will run as planned when ran as a screensaver if it ran as planned in the form of an application. Don't forget to add a RESTART command TLE at the end of the script when creating a multipart screensaver.