Do all alpha testing early and only once

files/shaders/objects_fragment.glsl

@@ -109,11 +109,14 @@ void main()
 
 #if @diffuseMap
     gl_FragData[0] = texture2D(diffuseMap, adjustedDiffuseUV);
-    alphaTest();
 #else
     gl_FragData[0] = vec4(1.0);
 #endif
 
+    vec4 diffuseColor = getDiffuseColor();
+    gl_FragData[0].a *= diffuseColor.a;
+    alphaTest();
+
 #if @detailMap
     gl_FragData[0].xyz *= texture2D(detailMap, detailMapUV).xyz * 2.0;
 #endif
@@ -152,10 +155,6 @@ void main()
 
 #endif
 
-    vec4 diffuseColor = getDiffuseColor();
-    gl_FragData[0].a *= diffuseColor.a;
-    alphaTest();
-
     float shadowing = unshadowedLightRatio(linearDepth);
     vec3 lighting;
 #if !PER_PIXEL_LIGHTING