Additions to ALS model shader suggested and partially implemented by Heiko Schulz: alternative reflection coloring model, Fresnel effect and normal map distortion of environment reflections in an efficient approximation

Effects/model-combined.eff

@@ -48,6 +48,8 @@ please see Docs/README.model-combined.eff for documentation
 		<reflection-enabled type="int">0</reflection-enabled>
 		<reflection-correction type="float">0.0</reflection-correction>
 		<reflect-map-enabled type="int">0</reflect-map-enabled>
+		<reflection-fresnel-factor type="float">0.0</reflection-fresnel-factor>
+		<reflection-type type="int">1</reflection-type>
 		<reflection-dynamic type="int">0</reflection-dynamic>
 		<texture n="4">
 			<image>Aircraft/Generic/Effects/ReflectMaps/reflectmap.png</image>
@@ -608,7 +610,7 @@ please see Docs/README.model-combined.eff for documentation
 				</value>
 		  	</uniform>
 			   
-			   <!-- 			reflection is used -->
+			   <!-- reflection is used -->
 			   <uniform>
 				   <name>refl_enabled</name>
 				   <type>int</type>
@@ -624,6 +626,15 @@ please see Docs/README.model-combined.eff for documentation
 					   <use>reflection-correction</use>
 				   </value>
 			   </uniform>
+
+			   <!-- Fresnel reflectivity -->
+			   <uniform>
+				   <name>refl_fresnel_factor</name>
+				   <type>float</type>
+				   <value>
+					   <use>reflection-fresnel-factor</use>
+				   </value>
+			   </uniform>
 			   
 			   <!-- use a reflection map-->
 			   <uniform>
@@ -633,6 +644,17 @@ please see Docs/README.model-combined.eff for documentation
 					   <use>reflect-map-enabled</use>
 				   </value>
 			   </uniform>
+
+			   <!-- how are colors merged in a reflection-->
+			   <uniform>
+				   <name>refl_type</name>
+				   <type>int</type>
+				   <value>
+					   <use>reflection-type</use>
+				   </value>
+			   </uniform>
+
+
 			   <!-- reflection is dynamic -->
 			   <uniform>
 				   <name>refl_dynamic</name>

Shaders/model-ALS-ultra.frag

@@ -33,6 +33,7 @@ uniform int lightmap_multi;
 uniform int nmap_dds;
 uniform int nmap_enabled;
 uniform int refl_enabled;
+uniform int refl_type;
 uniform int refl_map;
 uniform int grain_texture_enabled;
 uniform int rain_enabled;
@@ -52,6 +53,7 @@ uniform float lightmap_r_factor;
 uniform float nmap_tile;
 uniform float refl_correction;
 uniform float refl_fresnel;
+uniform float refl_fresnel_factor;
 uniform float refl_noise;
 uniform float refl_rainbow;
 uniform float grain_magnification;
@@ -233,17 +235,25 @@ void main (void)
 
     /// END grain overlay
 
+    vec3 reflVecN;
+
     ///BEGIN bump
     if (nmap_enabled > 0){
         N = nmap.rgb * 2.0 - 1.0;
+	// this is exact only for viewing under 90 degrees but much faster than the real solution
+	reflVecN = normalize (N.x * VTangent + N.y * VBinormal + N.z * reflVec);
         N = normalize(N.x * VTangent + N.y * VBinormal + N.z * VNormal);
         if (nmap_dds > 0)
             N = -N;
         } else {
             N = normalize(VNormal);
+	    reflVecN = reflVec;
         }
     ///END bump
-    vec4 reflection = textureCube(Environment, reflVec * dot(N,VNormal));
+
+
+
+    vec4 reflection = textureCube(Environment, reflVecN  );
     vec3 viewVec = normalize(vViewVec);
     float v      = abs(dot(viewVec, normalize(VNormal)));// Map a rainbowish color
     vec4 fresnel = texture2D(ReflGradientsTex, vec2(v, 0.75));
@@ -329,6 +339,12 @@ void main (void)
             } else {
                 reflFactor = gl_FrontMaterial.shininess* 0.0078125 + transparency_offset;
                 }
+
+	    // enhance low angle reflection by a fresnel term
+	    float fresnel_enhance = (1.0-smoothstep(0.0,0.4, dot(N,-normalize(vertVec)))) * refl_fresnel_factor;
+
+	    reflFactor+=fresnel_enhance;
+
             reflFactor = clamp(reflFactor, 0.0, 1.0);
 
             // add fringing fresnel and rainbow effects and modulate by reflection
@@ -339,7 +355,12 @@ void main (void)
             vec4 raincolor = vec4(noisecolor.rgb * reflFactor, 1.0);
             raincolor += Specular;
             raincolor *= light_diffuse;
-            mixedcolor = mix(texel, raincolor, reflFactor).rgb;
+
+	    if (refl_type == 1)
+            	{mixedcolor = mix(texel, raincolor, reflFactor).rgb;}
+	    else if (refl_type == 2)
+		{mixedcolor = ((texel +(reflcolor * reflFactor))-(0.5*reflFactor)).rgb;}
+
         } else {
             mixedcolor = texel.rgb;
         }