[Linux] Graphics vsync unchangeable

Archives Forums/BlitzMax Bug Reports/[Linux] Graphics vsync unchangeable

plash

(Posted 2010) [#1]

Unchangeable from on, that is.
Start up the code, note fps (should be rather high), press space (turning on vsync).
Now the fps should be at your monitor's refresh rate.
After that, trying to turn off vsync does not show any change in fps.
I've been able to visually see this (via lag - apart from fps alone) in another project.

SuperStrict

Framework brl.basic
Import brl.standardio
Import brl.glmax2d

' Fullscreen gives the same results
If Graphics(800, 600, 0) = Null Then Throw("Failed to create graphics")

Local vsync:Int = 0
While KeyHit(KEY_ESCAPE) = False
	Cls()
	If KeyHit(KEY_SPACE) = True Then vsync:~ 1
	DrawText("fps: " + TFPSCounter.GetFPS() + " vsync: " + vsync, 0, 0)
	DrawRect(100, 100, 100, 100)
	Flip(vsync)
	TFPSCounter.Update()
End While

Type TFPSCounter
	
	Global g_fps:Int, g_counter:Int
	Global g_time:Int = Millisecs()
	
	Function Update()
		g_counter:+1
		If MilliSecs() >= g_time
			g_fps = g_counter
			g_counter = 0
			g_time = MilliSecs() + 1000
		End If
	End Function
	
	Function GetFPS:Int()
		Return g_fps
	End Function
	
End Type

xlsior

(Posted 2010) [#2]

(Nevermind, didn't see the 'linux' part)

Otus	(Posted 2010) [#3]

For me it's unchangeable from 'off' (~235 fps) regardless of how the app starts.

marksibly

(Posted 2010) [#4]

Hi,

Not really sure what to do about vsync on Linux.

The enable/disable vsync extension seems to be pretty much randomly useful - as does whether vsync is on or off in fullscreen. Must be REALLY, REALLY tricky to implement or something...

bmx used to do a flaky 'is vsync working' timing loop, but this caused flickers on a few setups so I removed it and (stupidly) decided to 'trust' the driver - ie: if the extension was advertised as working, it should, erm, work. Perhaps I should restore this?

Currently then, the only way to guarantee vsync is to do manual timing and *try* to turn vsync off. Sorry about this, but Linux is pretty frustrating when it comes this stuff!