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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#include <string>
#include "VerticalSync.h"
#include "GL/myGL.h"
#include "System/myMath.h"
#include "System/Config/ConfigHandler.h"
#include "System/Log/ILog.h"
#include <SDL_video.h>
static constexpr int MAX_ADAPTIVE_INTERVAL = -6;
static constexpr int MAX_STANDARD_INTERVAL = +6;
static CVerticalSync instance;
CONFIG(int, VSync).
defaultValue(0).
minimumValue(MAX_ADAPTIVE_INTERVAL).
maximumValue(MAX_STANDARD_INTERVAL).
description(
"Synchronize buffer swaps with vertical blanking interval."
" Modes are -N (adaptive), +N (standard), or 0 (disabled)."
);
CVerticalSync* CVerticalSync::GetInstance()
{
return &instance;
}
void CVerticalSync::WrapNotifyOnChange()
{
configHandler->NotifyOnChange(this, {"VSync"});
}
void CVerticalSync::WrapRemoveObserver()
{
// can't do this in the dtor because VerticalSync outlives configHandler
configHandler->RemoveObserver(this);
}
void CVerticalSync::ConfigNotify(const std::string& key, const std::string& value)
{
SetInterval(configHandler->GetInt("VSync"));
}
void CVerticalSync::Toggle()
{
// no-arg switch, select smallest interval
switch (Clamp(SDL_GL_GetSwapInterval(), -1, 1)) {
case -1: { SetInterval( 0); } break;
case 0: { SetInterval(+1); } break;
case +1: { SetInterval(-1); } break;
default: {} break;
}
}
void CVerticalSync::SetInterval() { SetInterval(configHandler->GetInt("VSync")); }
void CVerticalSync::SetInterval(int i)
{
// recursion is already prevented (Set only notifies on changed
// values), this just avoids making the SDL calls a second time
if ((i = Clamp(i, MAX_ADAPTIVE_INTERVAL, MAX_STANDARD_INTERVAL)) == interval)
return;
configHandler->Set("VSync", interval = i);
#if defined HEADLESS
return;
#endif
// adaptive (delay swap iff frame-rate > vblank-rate)
if (interval < 0 && SDL_GL_SetSwapInterval(interval) == 0) {
LOG("[VSync::%s] interval=%d (adaptive)", __func__, interval);
return;
}
// standard (<interval> vblanks per swap)
if (interval > 0 && SDL_GL_SetSwapInterval(interval) == 0) {
LOG("[VSync::%s] interval=%d (standard)", __func__, interval);
return;
}
// disabled (never wait for vblank)
SDL_GL_SetSwapInterval(0);
LOG("[VSync::%s] interval=%d (disabled)", __func__, interval);
}
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