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49 lines
1.6 KiB
Plaintext
49 lines
1.6 KiB
Plaintext
{{DISPLAYTITLE:_GL}}
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In order to use OpenGL drawing commands, you must do so from inside a [[SUB]] procedure called '''_GL''', which enables the commands to be rendered.
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{{PageSyntax}}
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:[[SUB]] _GL
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:: ''REM Your OpenGL code here
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: [[END]] [[SUB]]
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{{PageDescription}}
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* OpenGL commands are valid outside of '''SUB _GL''', as long as the sub procedure exists in your code.
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* Attempting to use OpenGL commands without having '''SUB _GL''' in a program will result in a '''Syntax error''', even if the syntax is valid.
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* SUB '''_GL''' cannot be invoked manually. The code inside it will be called automatically at approximately 60 frames per second.
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* Using [[INPUT]] inside SUB '''_GL''' will crash your program.
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* If your program needs to perform any operations before SUB _GL must be run, it is recommended to use a shared variable as a flag to allow SUB _GL's contents to be run. See example below.
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==Example==
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{{CodeStart}} '' ''
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{{Cl|DIM}} allowGL {{Cl|AS}} {{Cl|_BYTE}}
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'perform startup routines like loading assets
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allowGL = -1 'sets allowGL to true so SUB _GL can run
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{{Cl|DO}}
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{{Cl|_LIMIT}} 1 'runs the main loop at 1 cycle per second
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'notice how the main loop doesn't do anything, as SUB _GL will be running
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'continuously.
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{{Cl|LOOP}}
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{{Cl|SUB}} {{Cl|_GL}}
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{{Cl|IF}} NOT allowGL {{Cl|THEN}} {{Cl|EXIT}} {{Cl|SUB}} 'used to bypass running the code below until
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' startup routines are done in the main module
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'OpenGL code starts here
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'The code in this area will be run automatically at ~60fps
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{{Cl|END}} {{Cl|SUB}} '' ''
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{{CodeEnd}}
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{{PageSeeAlso}}
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* [[_GLRENDER]]
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* [[SUB]]
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{{PageNavigation}}
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