added fallback shader

1 files changed, 15 insertions, 13 deletions

diff --git a/shaders/earth_fallback.fp b/shaders/earth_fallback.fp
index c8d6d2a..872d45b 100644
--- a/shaders/earth_fallback.fp
+++ b/shaders/earth_fallback.fp
@@ -10,27 +10,29 @@ void main()
 {
     vec3 fragNormal = normalize( fragmentNormal ) ;
 
-    float f = dot( fragNormal, normalize( lightVector  ) );
+    float light = dot( fragNormal, normalize( lightVector  ) );
     float c = dot( fragNormal, normalize( cameraVector ) );
     c = (c - 0.5) * 2.0 ;
 
-    vec4 color = texture2D(tex,gl_TexCoord[0].xy + vec2( 0.5, -0.2 ));
+    vec4 color = texture2D(tex,gl_TexCoord[0].xy);
 
-    float bluef = (1.0f / (1.0f + exp(-f * 150.0f)));
-
-    float bluef2  = (1.0f / (1.0f + exp(c * 20.0f))) * f;
-    float redf2   = (1.0f / (1.0f + exp(c * 20.0f))) * pow(f,2) * f;
+    float bluef2  = (1.0f / (1.0f + exp(c * 20.0f))) * light;
+    float redf2   = (1.0f / (1.0f + exp(c * 20.0f))) * pow(light,2.0) * light;
     float greenf2 = redf2;
 
-    float alpha   = (1.0f / (1.0f + exp(c * 30.0f))) * f;
-    
     /* Each color has its own drop off rate */
-    float greenf = (1.0f / (1.0f + exp(-f * 60.0f)));
-    float redf   = (1.0f / (1.0f + exp(-f * 30.0f)));
+
+    float bluef  = pow(light, 3.0) ;
+    float greenf = pow(light, 2.0) ;
+    float redf   = pow(light, 1.0) ;
+
+    if( bluef < 0.0 ) bluef = 0.0 ; 
+    if( greenf < 0.0 ) greenf = 0.0 ; 
+    if( redf < 0.0 ) redf = 0.0 ; 
 
     gl_FragColor = vec4(
-        redf*color[0] + 1000.0*redf2,
+        redf*color[0]   + 1000.0*redf2,
         greenf*color[1] + 1000.0*greenf2,
-        bluef*color[2] + 1000.0*bluef2,
-        1.0-1000.0*alpha );
+        bluef*color[2]  + 1000.0*bluef2,
+        1.0 );
 }