1 files changed, 36 insertions, 10 deletions
diff --git a/indra/newview/app_settings/shaders/class1/deferred/spotLightF.glsl b/indra/newview/app_settings/shaders/class1/deferred/spotLightF.glsl
index c918a42c73..adfe012e4d 100755
--- a/indra/newview/app_settings/shaders/class1/deferred/spotLightF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/spotLightF.glsl
@@ -65,16 +65,42 @@ uniform vec2 screen_res;
 
 uniform mat4 inv_proj;
 
-vec3 decode_normal (vec2 enc)
-{
-    vec2 fenc = enc*4-2;
-    float f = dot(fenc,fenc);
-    float g = sqrt(1-f/4);
-    vec3 n;
-    n.xy = fenc*g;
-    n.z = 1-f/2;
-    return n;
-}
+#ifdef SINGLE_FP_ONLY
+vec2 encode_normal(vec3 n)
+{
+	float f = sqrt(2 * n.z + 2);
+	return (n.xy / vec2(f)) + vec2(0.5f);
+}
+
+vec3 decode_normal (vec2 enc)
+{
+    vec2 fenc = enc - 0.5f;
+    float f = dot(fenc,fenc);
+    f = clamp(f,0.0f,1.0f);
+    float g = sqrt(1-f);
+    vec3 n;
+    n.xy = fenc*g;
+    n.z = 1.0f - (f * 0.5f);
+    return normalize(n);
+}
+#else
+vec2 encode_normal(vec3 n)
+{
+	float f = sqrt(8 * n.z + 8);
+	return n.xy / f + 0.5;
+}
+
+vec3 decode_normal (vec2 enc)
+{
+    vec2 fenc = enc*4-2;
+    float f = dot(fenc,fenc);
+    float g = sqrt(1-f/4);
+    vec3 n;
+    n.xy = fenc*g;
+    n.z = 1-f/2;
+    return n;
+}
+#endif
 
 vec4 correctWithGamma(vec4 col)
 {