Skybox image: swap red/blue in the uploaded texture

The procedural texture reaches the sky sampler with the red and blue channels
exchanged (blue sky rendered orange/yellow), while the game's own textures are
correct. Swap R/B in the decoded buffer so the sampled colours match the PNG.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/world.cpp b/src/world.cpp
index 092df77..38d302f 100644
--- a/src/world.cpp
+++ b/src/world.cpp
@@ -610,6 +610,15 @@ bool load_png_rgba(const char *path, std::vector<unsigned char> &pixels,
     }
   }
 
+  // The material system's procedural upload reaches the sampler with red and
+  // blue exchanged (the sky shader sees the blue background as orange). Swap
+  // them here so the sampled colours match the PNG.
+  for (size_t i = 0; i + 3 < pixels.size(); i += 4) {
+    unsigned char t = pixels[i];
+    pixels[i] = pixels[i + 2];
+    pixels[i + 2] = t;
+  }
+
   out_w = (int)w;
   out_h = (int)h;
   return true;