fixed shader for NVIDIA card

1 files changed, 10 insertions, 4 deletions

diff --git a/shaders/earth.fp b/shaders/earth.fp
index 3ca8ae9..7fd662c 100644
--- a/shaders/earth.fp
+++ b/shaders/earth.fp
@@ -17,9 +17,15 @@ void main()
 
     vec4 color = texture2D(tex,gl_TexCoord[0].xy + vec2( -time, -0.2 ));
 
-    float bluef2  = (1.0f / (1.0f + exp(c * 20.0f))) * f;
-    float redf2   = 200.0 * (1.0f / (1.0f + exp(c * 20.0f))) * pow(f,10.0) * f;
-    float greenf2 = 200.0 * (1.0f / (1.0f + exp(c * 20.0f))) * pow(f,15.0) * f;
+    float bluef2  = 0.0f;
+    float redf2   = 0.0f;
+    float greenf2 = 0.0f;
+
+    if( f > 0 ) {
+        bluef2  = (1.0f / (1.0f + exp(c * 20.0f))) * f;
+        redf2   = 200.0 * (1.0f / (1.0f + exp(c * 20.0f))) * pow(f,10.0) * f;
+        greenf2 = 200.0 * (1.0f / (1.0f + exp(c * 20.0f))) * pow(f,15.0) * f;
+    }
 
     float alpha   = (1.0f / (1.0f + exp(c * 30.0f))) * f;
     
@@ -32,5 +38,5 @@ void main()
         min(1.0,(redf*color[0] + 1000.0*redf2)),
         min(1.0,(greenf*color[1] + 1000.0*greenf2)),
         min(1.0,(bluef*color[2] + 1000.0*bluef2)),
-        min(1.0,1.0-1000.0*alpha) );
+        min(1.0,max(1.0-1000.0*alpha,0.0)) );
 }