[英]write game with java3d
I write this program but it has exception in line 我写了这个程序,但是它有例外
group.addChild(tg);
but when i add 但是当我添加
TransformGroup tg = new TransformGroup();
into the for loop block it runs with any problem please tell me it's reason. 进入for循环块,它会出现任何问题,请告诉我原因。
Thanks. 谢谢。
this is my code 这是我的代码
public BranchGroup Creat()
{
BranchGroup group = new BranchGroup();
TransformGroup tg = new TransformGroup();
for(float x = 0.0f; x < 1.0f; x += 0.1f)
{
Transform3D td = new Transform3D();
Vector3f vector3f = new Vector3f(x, x, x);
td.setTranslation(vector3f);
tg.setTransform(td);
tg.addChild(new Cone(0.05f, 0.1f));
group.addChild(tg);
}
return group;
}
this is it's exception 这是例外
Exception in thread "main" javax.media.j3d.MultipleParentException: Group.addChild: child already has a parent
at javax.media.j3d.GroupRetained.checkValidChild(GroupRetained.java:478)
at javax.media.j3d.GroupRetained.addChild(GroupRetained.java:487)
at javax.media.j3d.Group.addChild(Group.java:290)
at t39.Draw.Creat(Draw.java:68)
at t39.Draw.<init>(Draw.java:50)
at t39.Main.main(Main.java:22)
The same element can't exist more than once in the scene graph. 同一元素在场景图中不能重复存在。 When you create a new TransformGroup
within the loop it doesn't break the rule, but if you don't create a new one for every addChild()
you break this rule. 当您在循环中创建一个新的TransformGroup
,它不会违反规则,但是,如果您没有为每个addChild()
创建一个新的TransformGroup
,则会违反此规则。
(There are exceptions to the "only once in the graph", via weaker references instead of parent/child, eg for attributes) (“图中仅一次”是例外,通过较弱的引用而不是父/子引用,例如属性)
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