Calculate FPS stuff even if frame is skipped

I decided ultimately to actually keep the frame skip optimization disabled, because I think it is actually a little bit helpful that you can still get accurate rendering perfstats while paused, however if we decide otherwise then we can have this optimization back without making the game act like it's lagging.

src/screen.c

@@ -451,18 +451,50 @@ boolean SCR_IsAspectCorrect(INT32 width, INT32 height)
 // moved out of os-specific code for consistency
 static boolean fpsgraph[TICRATE];
 static tic_t lasttic;
+static tic_t totaltics;
 
-void SCR_DisplayTicRate(void)
+static UINT32 fpstime = 0;
+static UINT32 lastupdatetime = 0;
+
+#define FPSUPDATERATE 1/20 // What fraction of a second to update at. The fraction will not simplify to 0, trust me.
+#define FPSMAXSAMPLES 16
+
+static UINT32 fpssamples[FPSMAXSAMPLES];
+static UINT32 fpssampleslen = 0;
+static UINT32 fpssum = 0;
+double aproxfps = 0.0f;
+
+void SCR_CalcAproxFps(void)
 {
-	tic_t i;
+	tic_t i = 0;
 	tic_t ontic = I_GetTime();
-	tic_t totaltics = 0;
-	INT32 ticcntcolor = 0;
-	const INT32 h = vid.height-(8*vid.dupy);
 
-	if (gamestate == GS_NULL)
-		return;
+	totaltics = 0;
 
+	// Update FPS time
+	if (I_PreciseToMicros(fpstime - lastupdatetime) > 1000000 * FPSUPDATERATE)
+	{
+		if (fpssampleslen == FPSMAXSAMPLES)
+		{
+			fpssum -= fpssamples[0];
+
+			for (i = 1; i < fpssampleslen; i++)
+				fpssamples[i-1] = fpssamples[i];
+		}
+		else
+			fpssampleslen++;
+
+		fpssamples[fpssampleslen-1] = I_GetPreciseTime() - fpstime;
+		fpssum += fpssamples[fpssampleslen-1];
+
+		aproxfps = 1000000 / (I_PreciseToMicros(fpssum) / (double)fpssampleslen);
+
+		lastupdatetime = I_GetPreciseTime();
+	}
+
+	fpstime = I_GetPreciseTime();
+
+	// Update ticrate time
 	for (i = lasttic + 1; i < TICRATE+lasttic && i < ontic; ++i)
 		fpsgraph[i % TICRATE] = false;
 
@@ -472,21 +504,30 @@ void SCR_DisplayTicRate(void)
 		if (fpsgraph[i])
 			++totaltics;
 
+	lasttic = ontic;
+}
+
+void SCR_DisplayTicRate(void)
+{
+	INT32 ticcntcolor = 0;
+	const INT32 h = vid.height-(8*vid.dupy);
+
+	if (gamestate == GS_NULL)
+		return;
+
 	if (totaltics <= TICRATE/2) ticcntcolor = V_REDMAP;
 	else if (totaltics == TICRATE) ticcntcolor = V_GREENMAP;
 
 	if (cv_ticrate.value == 2) // compact counter
-		V_DrawString(vid.width-(16*vid.dupx), h,
-			ticcntcolor|V_NOSCALESTART|V_USERHUDTRANS, va("%02d", totaltics));
+		V_DrawString(vid.width-(24*vid.dupx), h,
+			ticcntcolor|V_NOSCALESTART|V_USERHUDTRANS, va("%03.0f", aproxfps));
 	else if (cv_ticrate.value == 1) // full counter
 	{
-		V_DrawString(vid.width-(72*vid.dupx), h,
+		V_DrawString(vid.width-(88*vid.dupx), h,
 			V_YELLOWMAP|V_NOSCALESTART|V_USERHUDTRANS, "FPS:");
-		V_DrawString(vid.width-(40*vid.dupx), h,
-			ticcntcolor|V_NOSCALESTART|V_USERHUDTRANS, va("%02d/%02u", totaltics, TICRATE));
+		V_DrawString(vid.width-(56*vid.dupx), h,
+			ticcntcolor|V_NOSCALESTART|V_USERHUDTRANS, va("%03.0f/%03u", aproxfps, TICRATE));
 	}
-
-	lasttic = ontic;
 }
 
 void SCR_DisplayLocalPing(void)

src/screen.h

@@ -181,6 +181,7 @@ extern boolean R_SSE2;
 extern viddef_t vid;
 extern INT32 setmodeneeded; // mode number to set if needed, or 0
 extern UINT8 setrenderneeded;
+extern double aproxfps;
 
 void SCR_ChangeRenderer(void);
 
@@ -211,6 +212,8 @@ void SCR_CheckDefaultMode(void);
 // Set the mode number which is saved in the config
 void SCR_SetDefaultMode(void);
 
+void SCR_CalcAproxFps(void);
+
 FUNCMATH boolean SCR_IsAspectCorrect(INT32 width, INT32 height);
 
 // move out to main code for consistency

src/sdl/i_video.c

@@ -1178,12 +1178,11 @@ void I_UpdateNoBlit(void)
 // from PrBoom's src/SDL/i_video.c
 static inline boolean I_SkipFrame(void)
 {
-#if 0
+#if 1
+	return false;
+#else
 	static boolean skip = false;
 
-	if (rendermode != render_soft)
-		return false;
-
 	skip = !skip;
 
 	switch (gamestate)
@@ -1199,7 +1198,6 @@ static inline boolean I_SkipFrame(void)
 			return false;
 	}
 #endif
-	return false;
 }
 
 //
@@ -1210,6 +1208,8 @@ void I_FinishUpdate(void)
 	if (rendermode == render_none)
 		return; //Alam: No software or OpenGl surface
 
+	SCR_CalcAproxFps();
+
 	if (I_SkipFrame())
 		return;