diff --git a/lib/shader.js b/lib/shader.js
index 3cf40f1..a4b1f2a 100644
--- a/lib/shader.js
+++ b/lib/shader.js
@@ -87,7 +87,7 @@ Shader.prototype.fragmentMain = [
     " float l = dot(color.rgb, W);",
     " color.a = iTransition < 1.0 ? iTransition * clamp(0.2,1.0,l): 1.0;",
     "#else",
-    " color.a = iTransition < 1.0 ? 0.66: 1.0;",
+    " color.a = iTransition < 1.0 ? iTransition * max(color.b, max(color.r, color.g)): 1.0;",
     "#endif",
     " gl_FragColor = color;",
     "}"