game_dir: glsl: implemented discarding non-opaque texels during light pass on transparent meshes

Author: SNMetamorph

game_dir/glsl/forward/light_bmodel_fp.glsl

@@ -202,6 +202,12 @@ void main()
 #endif
 #endif
 
+#if !defined( HAS_TRANSPARENCY )
+	// skipping lighting for fragments that aren't opaque
+	if( albedo.a < 0.999 )
+		discard;
+#endif
+
 	vec3 light = u_LightDiffuse * DLIGHT_SCALE;	// light color
 	float shadow = 1.0;
 	float NdotL = saturate( dot( N, L ));

game_dir/glsl/forward/light_studio_fp.glsl

@@ -163,6 +163,13 @@ void main( void )
 	}
 #endif
 #endif
+
+#if !defined( HAS_TRANSPARENCY )
+	// skipping lighting for fragments that aren't opaque
+	if( diffuse.a < 0.999 )
+		discard;
+#endif
+
 	if (shadow <= 0.0) 
 		discard; // fast reject