Unit assembler shader fix

core/src/mindustry/graphics/Shaders.java

@@ -232,6 +232,8 @@ public class Shaders{
 
     public static class BlockBuildShader extends LoadShader{
         public float progress;
+        //Alpha changes the opacity of *everything*, while the provided batch color only changes the outline
+        public float alpha = 1f;
         public TextureRegion region = new TextureRegion();
         public float time;
 
@@ -243,6 +245,7 @@ public class Shaders{
         public void apply(){
             setUniformf("u_progress", progress);
             setUniformf("u_time", time);
+            setUniformf("u_alpha", alpha);
 
             if(region.texture == null){
                 setUniformf("u_uv", 0f, 0f);