SuperTuxKart 1.5 upstream source (from official release tarball)

data/shaders/utils/decodeNormal.frag

@@ -0,0 +1,9 @@
+vec3 DecodeNormal(vec2 n)
+{
+    n = n * 2.0 - 1.0;
+    vec3 ret = vec3(n.x, n.y, 1.0 - abs(n.x) - abs(n.y));
+    float t = max(-ret.z, 0.0);
+    ret.x += ret.x >= 0.0 ? -t : t;
+    ret.y += ret.y >= 0.0 ? -t : t;
+    return normalize(ret);
+}