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This command allows you to switch which graphic page will be drawn to and shown. Graphic pages are 6 512x512 images you can edit. They can be used as sprite sheets and background tile sheets with the SPPAGE and BGPAGE commands respectively. There is a negative graphic page that contains the font, but it can only be used with GCOPY.
GPAGE display%, draw%GPAGE OUT display%, draw%| Parameter/Output | Description |
|---|---|
| display% | The graphic page to display. |
| draw% | The graphic page to use with drawing commands. |
This example displays each of the graphic pages (excluding the font page) for 1 second. After that, it edits one page while displaying another.
ACLS
FOR I=0 TO 5
'Run through each of the 6 graphic pages, showing their default graphics.
GPAGE I,I
?"Showing graphic page ";I;"."
WAIT 60 'Wait a second.
NEXT I
'Edit one page while showing another page
GPAGE 4,5
?"Showing graphic page 4 and editing graphic page 5."
GBOX 0,0,31,31,&hFF1F3F7F 'Pretty color
WAIT 60
GPAGE 5,4
?"Showing graphic page 5 and editing graphic page 4."
GBOX 32,32,63,63,&hFF7F1F3F 'Also just as pretty color
WAIT 60
?"Showing graphic page 5."
GPAGE 5,5
Drawing to one page and displaying another can create a “double-buffered” effect, where if one frame takes too long to draw, the gamer will see a complete picture instead of the currently drawing one.
ACLS
'This variable will hold our buffer page.
VAR BUFFPAGE=0
WHILE 1
'Set current page to either 0 or 1.
GPAGE BUFFPAGE,!BUFFPAGE
'Clears page we're going to write to.
GCLS
'Swaps buffer. 0 becomes 1, 1 becomes 0.
BUFFPAGE=!BUFFPAGE
FOR I=0 TO 15
'Draw some random boxes
GBOX RND(400),RND(240),RND(400),RND(240)
VSYNC 1 'Fake lag.
VSYNC
WEND
| Error | Cause |
|---|---|
| Out of Range | Either display% or draw% is less than 0 or greater than 5. If you’re trying to display the font page, you’ll need to GCOPY it to an accessible page. |
Fixed a bug where using GPAGE after setting a GCLIP area would reset the GCLIP area. 1
OUT variant added. 1
1 SmileBoom, “Additions/Changes in Ver. 3.2.0 (June 17, 2015)” http://smilebasic.com/debug/archive/