- I have no idea why a fov of exactly 90° does not work.

Changing this by one in either direction makes the problem go away.

source/blood/src/view.cpp

@@ -3103,7 +3103,10 @@ void viewDrawScreen(bool sceneonly)
             newaspect_enable = 1;
             videoSetCorrectedAspect();
         }
-        renderSetAspect(Blrintf(float(viewingrange) * tanf(r_fov * (PI / 360.f))), yxaspect);
+
+        int v1 = Blrintf(double(viewingrange) * tan(r_fov * (PI / 360.)));
+
+        renderSetAspect(v1, yxaspect);
         int cX = gView->pSprite->x;
         int cY = gView->pSprite->y;
         int cZ = gView->zView;

source/build/include/compat.h

@@ -11,6 +11,8 @@
 # include "windows_inc.h"
 #endif
 
+#include "xs_Float.h"
+
 ////////// Compiler detection //////////
 
 #ifdef __GNUC__
@@ -499,9 +501,9 @@ static inline int32_t atoi_safe(const char *str) { return (int32_t)strtoll(str,
 #define Batoi(x) atoi_safe(x)
 #define Batol(str) (strtol(str, NULL, 10))
 
-static constexpr inline int Blrintf(const double x)
+static inline int Blrintf(const double x)
 {
-    return int(x);
+    return xs_CRoundToInt(x);
 }
 
 #if defined(__arm__)

source/build/src/engine.cpp

@@ -10062,6 +10062,7 @@ void videoSetViewableArea(int32_t x1, int32_t y1, int32_t x2, int32_t y2)
 //
 void renderSetAspect(int32_t daxrange, int32_t daaspect)
 {
+    if (daxrange == 65536) daxrange--;  // This doesn't work correctly with 65536. All other values are fine. No idea where this is evaluated wrong.
     viewingrange = daxrange;
     viewingrangerecip = divscale32(1,daxrange);
 #ifdef USE_OPENGL

source/duke3d/src/game.cpp

@@ -755,7 +755,7 @@ void G_DrawRooms(int32_t playerNum, int32_t smoothRatio)
 #endif
                                   )));
 
-        vr = Blrintf(float(vr) * tanf(r_fov * (fPI/360.f)));
+        vr = Blrintf(double(vr) * tan(r_fov * (PI/360.)));
 
         if (!r_usenewaspect)
             renderSetAspect(vr, yxaspect);