engine: cap framerate to 1000 even if r_maxfps is 0

For anyone that really thinks they need more than 1000 fps, "r_maxfps -2" will revert to the previous completely unthrottled behavior.

source/build/include/baselayer.h

@@ -323,15 +323,14 @@ void maybe_redirect_outputs(void);
 extern uint64_t g_frameDelay;
 static inline uint64_t calcFrameDelay(int maxFPS)
 {
-    uint64_t perfFreq = timerGetNanoTickRate();
-
     switch (maxFPS)
     {
+        case -2: return 0;
         case -1: maxFPS = refreshfreq; break;
-        case 0: perfFreq = 0; break;
+        case 0: maxFPS = 1000; break;
     }
 
-    return tabledivide64(perfFreq, maxFPS);
+    return tabledivide64(timerGetNanoTickRate(), maxFPS);
 }
 extern int engineFPSLimit(void);
 #ifdef __cplusplus

source/build/src/baselayer.cpp

@@ -818,7 +818,7 @@ int32_t baselayer_init(void)
         { "r_novoxmips","turn off/on the use of mipmaps when rendering 8-bit voxels",(void *) &novoxmips, CVAR_BOOL, 0, 1 },
         { "r_rotatespriteinterp", "interpolate repeated rotatesprite calls", (void *)&r_rotatespriteinterp, CVAR_BOOL, 0, 1 },
         { "r_voxels","enable/disable automatic sprite->voxel rendering",(void *) &usevoxels, CVAR_BOOL, 0, 1 },
-        { "r_maxfps", "limit the frame rate", (void *)&r_maxfps, CVAR_INT | CVAR_FUNCPTR, -1, 1000 },
+        { "r_maxfps", "limit the frame rate", (void *)&r_maxfps, CVAR_INT | CVAR_FUNCPTR, -2, 1000 },
 #ifdef YAX_ENABLE
         { "r_tror_nomaskpass", "enable/disable additional pass in TROR software rendering", (void *)&r_tror_nomaskpass, CVAR_BOOL, 0, 1 },
 #endif
@@ -897,7 +897,7 @@ int engineFPSLimit(void)
     static uint64_t nextFrameTicks;
     static uint64_t savedFrameDelay;
 
-    if (!r_maxfps)
+    if (r_maxfps == -2)
         return true;
 
     g_frameDelay = calcFrameDelay(r_maxfps);