Image: fix mipmap generation flags not properly being updated

jme3-core/src/main/java/com/jme3/texture/Image.java

@@ -421,7 +421,8 @@ public class Image extends NativeObject implements Savable /*, Cloneable*/ {
     
     /**
      * @return True if the image needs to have mipmaps generated
-     * for it (as requested by the texture).
+     * for it (as requested by the texture). This stays true even
+     * after mipmaps have been generated.
      */
     public boolean isGeneratedMipmapsRequired() {
         return needGeneratedMips;
@@ -434,8 +435,9 @@ public class Image extends NativeObject implements Savable /*, Cloneable*/ {
     @Override
     public void setUpdateNeeded() {
         super.setUpdateNeeded();
-        if (!isGeneratedMipmapsRequired() && !hasMipmaps()) {
+        if (isGeneratedMipmapsRequired() && !hasMipmaps()) {
-            setNeedGeneratedMipmaps();
+            // Mipmaps are no longer valid, since the image was changed.
+            setMipmapsGenerated(false);
         }
     }
     
@@ -527,12 +529,14 @@ public class Image extends NativeObject implements Savable /*, Cloneable*/ {
         
         this();
 
-        if (mipMapSizes != null && mipMapSizes.length <= 1) {
+        if (mipMapSizes != null) {
+            if (mipMapSizes.length <= 1) {
                 mipMapSizes = null;
             } else {
                 needGeneratedMips = false;
                 mipsWereGenerated = true;
             }
+        }
 
         setFormat(format);
         this.width = width;