Function PerformWipe

source/common/2d/wipe.cpp:517–570

void PerformWipe(FTexture* startimg, FTexture* endimg, int wipe_type, bool stopsound, std::function<void()> overlaydrawer)
{
	// wipe update
	uint64_t wipestart, nowtime, diff;
	double diff_frac;
	bool done;

	GSnd->SetSfxPaused(true, 1);
	I_FreezeTime(true);
	twod->End();
	assert(startimg != nullptr && endimg != nullptr);
	auto starttex = MakeGameTexture(startimg, nullptr, ETextureType::SWCanvas);
	auto endtex = MakeGameTexture(endimg, nullptr, ETextureType::SWCanvas);
	auto wiper = Wiper::Create(wipe_type);
	wiper->SetTextures(starttex, endtex);

	wipestart = I_msTime();

	do
	{
		if (wiper->Interpolatable() && !cl_capfps)
		{
			nowtime = I_msTime();
			diff_frac = (nowtime - wipestart) * 40. / 1000.;	// Using 35 here feels too slow.
			wipestart = nowtime;
			twod->Begin(screen->GetWidth(), screen->GetHeight());
			done = wiper->RunInterpolated(diff_frac);
			if (overlaydrawer) overlaydrawer();
			twod->End();
			screen->Update();
			twod->OnFrameDone();
		}
		else
		{
			do
			{
				I_WaitVBL(2);
				nowtime = I_msTime();
				diff = (nowtime - wipestart) * 40 / 1000;	// Using 35 here feels too slow.
			} while (diff < 1);
			wipestart = nowtime;
			twod->Begin(screen->GetWidth(), screen->GetHeight());
			done = wiper->Run(1);
			if (overlaydrawer) overlaydrawer();
			twod->End();
			screen->Update();
			twod->OnFrameDone();
		}
	} while (!done);
	delete wiper;
	I_FreezeTime(false);
	GSnd->SetSfxPaused(false, 1);

}