From d9d6255107b40290ca5a2695dc417bdd1fca2d7a Mon Sep 17 00:00:00 2001
From: Frederic Bouvier <fredfgfs01@free.fr>
Date: Sun, 22 Jul 2012 19:53:27 +0200
Subject: [PATCH 1/2] Fix 'Phong distortion' artifact on specular lighting and
 disappearing emission (due to undefined pow(0,0) called) in Rembrandt -
 forgotten shaders

---
 Shaders/sunlight-nofiltering.frag | 15 +++++++--------
 Shaders/sunlight-noshadow.frag    | 15 +++++++--------
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/Shaders/sunlight-nofiltering.frag b/Shaders/sunlight-nofiltering.frag
index af9d0699e..4a6c2e3a0 100644
--- a/Shaders/sunlight-nofiltering.frag
+++ b/Shaders/sunlight-nofiltering.frag
@@ -61,8 +61,6 @@ void main() {
     if ( spec_emis.a < 0.1 )
         discard;
     vec3 normal = normal_decode(texture2D( normal_tex, coords ).rg);
-    float len = length(normal);
-    normal /= len;
     vec3 viewDir = normalize(ray);
     vec3 pos = position( viewDir, coords, depth_tex );
 
@@ -72,14 +70,15 @@ void main() {
     lightDir = normalize( lightDir );
     vec3 color = texture2D( color_tex, coords ).rgb;
     vec3 Idiff = clamp( dot( lightDir, normal ), 0.0, 1.0 ) * color * fg_SunDiffuseColor.rgb;
-    vec3 halfDir = lightDir - viewDir;
-    len = length( halfDir );
+    vec3 halfDir = normalize( lightDir - viewDir );
     vec3 Ispec = vec3(0.0);
     vec3 Iemis = spec_emis.z * color;
-    if (len > 0.0001) {
-        halfDir /= len;
-        Ispec = pow( clamp( dot( halfDir, normal ), 0.0, 1.0 ), spec_emis.y * 128.0 ) * spec_emis.x * fg_SunSpecularColor.rgb;
-    }
+
+    float cosAngIncidence = clamp(dot(normal, lightDir), 0.0, 1.0);
+    float blinnTerm = clamp( dot( halfDir, normal ), 0.0, 1.0 );
+
+    if (cosAngIncidence > 0.0)
+        Ispec = pow( blinnTerm, spec_emis.y * 128.0 ) * spec_emis.x * fg_SunSpecularColor.rgb;
 
     float matID = texture2D( color_tex, coords ).a * 255.0;
     if (matID >= 254.0)
diff --git a/Shaders/sunlight-noshadow.frag b/Shaders/sunlight-noshadow.frag
index 2045b0f1c..23ad141d0 100644
--- a/Shaders/sunlight-noshadow.frag
+++ b/Shaders/sunlight-noshadow.frag
@@ -17,22 +17,21 @@ void main() {
     if ( spec_emis.a < 0.1 )
         discard;
     vec3 normal = normal_decode(texture2D( normal_tex, coords ).rg);
-    float len = length(normal);
-    normal /= len;
     vec3 viewDir = normalize(ray);
 
     vec3 lightDir = (fg_ViewMatrix * vec4( fg_SunDirection, 0.0 )).xyz;
     lightDir = normalize( lightDir );
     vec3 color = texture2D( color_tex, coords ).rgb;
     vec3 Idiff = clamp( dot( lightDir, normal ), 0.0, 1.0 ) * color * fg_SunDiffuseColor.rgb;
-    vec3 halfDir = lightDir - viewDir;
-    len = length( halfDir );
+    vec3 halfDir = normalize( lightDir - viewDir );
     vec3 Ispec = vec3(0.0);
     vec3 Iemis = spec_emis.z * color;
-    if (len > 0.0001) {
-        halfDir /= len;
-        Ispec = pow( clamp( dot( halfDir, normal ), 0.0, 1.0 ), spec_emis.y * 255.0 ) * spec_emis.x * fg_SunSpecularColor.rgb;
-    }
+
+    float cosAngIncidence = clamp(dot(normal, lightDir), 0.0, 1.0);
+    float blinnTerm = clamp( dot( halfDir, normal ), 0.0, 1.0 );
+
+    if (cosAngIncidence > 0.0)
+        Ispec = pow( blinnTerm, spec_emis.y * 128.0 ) * spec_emis.x * fg_SunSpecularColor.rgb;
 
     float matID = texture2D( color_tex, coords ).a * 255.0;
     if (matID >= 254.0)

From 0604e3975bb725132cd5f2e946fc2f221f29e6bb Mon Sep 17 00:00:00 2001
From: Stuart Buchanan <stuart_d_buchanan@yahoo.co.uk>
Date: Tue, 24 Jul 2012 22:12:11 +0100
Subject: [PATCH 2/2] Add an additional random rotation to trees so the quads
 are not all oriented N/S and E/W, helping to disguise the limited set of
 textures used.

---
 Shaders/tree.vert | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Shaders/tree.vert b/Shaders/tree.vert
index cdaa0ce09..65b3d2d7e 100644
--- a/Shaders/tree.vert
+++ b/Shaders/tree.vert
@@ -18,8 +18,12 @@ void main(void)
   float numVarieties = gl_Normal.z;
   float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties;
   texFract += floor(gl_MultiTexCoord0.x) / numVarieties;
-  float sr = sin(gl_FogCoord);
-  float cr = cos(gl_FogCoord);
+  
+  // Determine the rotation for the tree.  The Fog Coordinate provides rotation information
+  // to rotate one of the quands by 90 degrees.  We then apply an additional position seed
+  // so that trees aren't all oriented N/S
+  float sr = sin(gl_FogCoord + gl_Color.x);
+  float cr = cos(gl_FogCoord + gl_Color.x);
   gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0);
 
   // scaling