Better skybox position precision

src/game/skybox.c

@@ -10,6 +10,9 @@
 #include "segment2.h"
 #include "sm64.h"
 
+#ifndef TARGET_N64
+#define BETTER_SKYBOX_POSITION_PRECISION
+#endif
 
 /**
  * @file skybox.c
@@ -49,10 +52,17 @@ struct Skybox {
     u16 yaw;
     /// The camera's pitch, which is bounded by +-16384, which maps to -90 to 90 degrees
     s16 pitch;
+#ifdef BETTER_SKYBOX_POSITION_PRECISION
+    /// The skybox's X position in world space
+    f32 scaledX;
+    /// The skybox's Y position in world space
+    f32 scaledY;
+#else
     /// The skybox's X position in world space
     s32 scaledX;
     /// The skybox's Y position in world space
     s32 scaledY;
+#endif
 
     /// The index of the upper-left tile in the 3x3 grid that gets drawn
     s32 upperLeftTile;
@@ -135,17 +145,32 @@ u8 sSkyboxColors[][3] = {
  *                 (how far is the camera rotated from 0, scaled 0 to 1)   *
  *                 (the screen width)
  */
-int calculate_skybox_scaled_x(s8 player, f32 fov) {
+#ifdef BETTER_SKYBOX_POSITION_PRECISION
+f32
+#else
+s32
+#endif
+calculate_skybox_scaled_x(s8 player, f32 fov) {
     f32 yaw = sSkyBoxInfo[player].yaw;
 
     //! double literals are used instead of floats
     f32 yawScaled = SCREEN_WIDTH * 360.0 * yaw / (fov * 65536.0);
+
+#ifdef BETTER_SKYBOX_POSITION_PRECISION
+    f32 scaledX = yawScaled;
+
+    if (scaledX > SKYBOX_WIDTH) {
+        scaledX -= (s32) scaledX / SKYBOX_WIDTH * SKYBOX_WIDTH;
+    }
+#else
     // Round the scaled yaw. Since yaw is a u16, it doesn't need to check for < 0
     s32 scaledX = yawScaled + 0.5;
 
     if (scaledX > SKYBOX_WIDTH) {
         scaledX -= scaledX / SKYBOX_WIDTH * SKYBOX_WIDTH;
     }
+#endif
+
     return SKYBOX_WIDTH - scaledX;
 }
 
@@ -155,17 +180,27 @@ int calculate_skybox_scaled_x(s8 player, f32 fov) {
  * fov may have been used in an earlier version, but the developers changed the function to always use
  * 90 degrees.
  */
-int calculate_skybox_scaled_y(s8 player, UNUSED f32 fov) {
+#ifdef BETTER_SKYBOX_POSITION_PRECISION
+f32
+#else
+s32
+#endif
+calculate_skybox_scaled_y(s8 player, UNUSED f32 fov) {
     // Convert pitch to degrees. Pitch is bounded between -90 (looking down) and 90 (looking up).
     f32 pitchInDegrees = (f32) sSkyBoxInfo[player].pitch * 360.0 / 65535.0;
 
     // Scale by 360 / fov
     f32 degreesToScale = 360.0f * pitchInDegrees / 90.0;
+
+#ifdef BETTER_SKYBOX_POSITION_PRECISION
+    f32 scaledY = degreesToScale + 5 * SKYBOX_TILE_HEIGHT;
+#else
     s32 roundedY = round_float(degreesToScale);
 
     // Since pitch can be negative, and the tile grid starts 1 octant above the camera's focus, add
     // 5 octants to the y position
     s32 scaledY = roundedY + 5 * SKYBOX_TILE_HEIGHT;
+#endif
 
     if (scaledY > SKYBOX_HEIGHT) {
         scaledY = SKYBOX_HEIGHT;