Remove use_texture_alpha compatibility code for nodeboxes & meshes (#13929)

src/nodedef.h

@@ -258,7 +258,7 @@ enum AlphaMode : u8 {
 	ALPHAMODE_BLEND,
 	ALPHAMODE_CLIP,
 	ALPHAMODE_OPAQUE,
-	ALPHAMODE_LEGACY_COMPAT, /* means either opaque or clip */
+	ALPHAMODE_LEGACY_COMPAT, /* only sent by old servers, equals OPAQUE */
 };
 
 
@@ -466,11 +466,9 @@ struct ContentFeatures
 		case NDT_NORMAL:
 		case NDT_LIQUID:
 		case NDT_FLOWINGLIQUID:
-			alpha = ALPHAMODE_OPAQUE;
-			break;
 		case NDT_NODEBOX:
 		case NDT_MESH:
-			alpha = ALPHAMODE_LEGACY_COMPAT; // this should eventually be OPAQUE
+			alpha = ALPHAMODE_OPAQUE;
 			break;
 		default:
 			alpha = ALPHAMODE_CLIP;
@@ -529,16 +527,6 @@ struct ContentFeatures
 #endif
 
 private:
-#ifndef SERVER
-	/*
-	 * Checks if any tile texture has any transparent pixels.
-	 * Prints a warning and returns true if that is the case, false otherwise.
-	 * This is supposed to be used for use_texture_alpha backwards compatibility.
-	 */
-	bool textureAlphaCheck(ITextureSource *tsrc, const TileDef *tiles,
-		int length);
-#endif
-
 	void setAlphaFromLegacy(u8 legacy_alpha);
 
 	u8 getAlphaForLegacy() const;