how to display bob correctly with double buffering

Blackgoat · 15 March 2016, 10:25

Hello, i have scrolling playfield, and some bobs... and they flicker lot when screen is scrolling...

Its supposed to be, because according to AMOS manuals, if double buffering is used, to avoid bob flickering, there must be "genuine connection" and "sensible progress" between screen 0 and screen 1... ok, what it means??

now i have something like this:

autoback 0
double buffer

rem mainloop
do

bob clear

...here is joystick check, changing bob & screen coordinates ...

Screen copy physic to logic
screen swap : wait vbl

bob draw

loop

I tried play with bob update, pastebob etc. but it usually make flickering worse, or make some strange effect like double bob into two images which moves separatelly

Samurai_Crow · 15 March 2016, 18:34

The Wait Vbl goes before the screen swap.

Blackgoat · 15 March 2016, 22:10

Thank you, problem solved. Still there is some minor flickering of few colours, probably because screen copy is faster than blitter (if I put somethink like wait 16 into main loop, it stop, but then scrolling is unusable slow...)

15 March 2016, 10:25	#1
Blackgoat Registered User Join Date: Feb 2016 Location: Czech Republic Posts: 26	how to display bob correctly with double buffering Hello, i have scrolling playfield, and some bobs... and they flicker lot when screen is scrolling... Its supposed to be, because according to AMOS manuals, if double buffering is used, to avoid bob flickering, there must be "genuine connection" and "sensible progress" between screen 0 and screen 1... ok, what it means?? now i have something like this: autoback 0 double buffer rem mainloop do bob clear ...here is joystick check, changing bob & screen coordinates ... Screen copy physic to logic screen swap : wait vbl bob draw loop I tried play with bob update, pastebob etc. but it usually make flickering worse, or make some strange effect like double bob into two images which moves separatelly

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15 March 2016, 18:34	#2
Samurai_Crow Total Chaos forever! Join Date: Aug 2007 Location: Waterville, MN, USA Age: 49 Posts: 2,186	The Wait Vbl goes before the screen swap.

15 March 2016, 22:10	#3
Blackgoat Registered User Join Date: Feb 2016 Location: Czech Republic Posts: 26	Thank you, problem solved. Still there is some minor flickering of few colours, probably because screen copy is faster than blitter (if I put somethink like wait 16 into main loop, it stop, but then scrolling is unusable slow...)

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