it is done

core/src/mindustry/entities/traits/ScaleTrait.java

@@ -0,0 +1,43 @@
+package mindustry.entities.traits;
+
+import arc.math.Interpolation;
+
+public interface ScaleTrait{
+    /** 0 to 1. */
+    float fin();
+
+    /** 1 to 0 */
+    default float fout(){
+        return 1f - fin();
+    }
+
+    /** 1 to 0 */
+    default float fout(Interpolation i){
+        return i.apply(fout());
+    }
+
+    /** 1 to 0, ending at the specified margin */
+    default float fout(float margin){
+        float f = fin();
+        if(f >= 1f - margin){
+            return 1f - (f - (1f - margin)) / margin;
+        }else{
+            return 1f;
+        }
+    }
+
+    /** 0 to 1 **/
+    default float fin(Interpolation i){
+        return i.apply(fin());
+    }
+
+    /** 0 to 1 */
+    default float finpow(){
+        return Interpolation.pow3Out.apply(fin());
+    }
+
+    /** 0 to 1 to 0 */
+    default float fslope(){
+        return (0.5f - Math.abs(fin() - 0.5f)) * 2f;
+    }
+}