How to set position use anchor point Vec2(0.5, 0.5) like cocos creator?

[antn9x]

How to set position in center of parent node with anchor point (0.5, 0.5) like cocos creator do?

[DelinWorks]

you can use node->setAnchor(0.5F, 0.5F);

[aismann]

Why you set it not on each new Sprite?
If you change it on ALL nodes also the parent node ist changed ( Not tested)

[antn9x]

Because I want to have behavior like cocos creator with default is anchor (0.5, 0.5) and child node will draw at center of parent node.

[DelinWorks]

you don't have to change the node.cpp file to anchor a node. You should make that node anchor to 0.5 from within your project code not the engine's, not its source, everything derives from node so if you set anchor to 0.5 in node.cpp then everything including the camera will be of 0.5 anchor so there is no effect, you should make that change in the helloworld class of the project.

[antn9x]

Do you have any sample code worked?

[DelinWorks]

you need to locate HelloWorldScene.cpp and change the code where it creates the hello world sprite so that it anchors to 0.5, at first you will notice that it's indeed in the middle but that's because the position was shifted beforehand, you need to comment the set position line and set the anchor to 0.5 like this:

    // add "HelloWorld" splash screen"
    auto sprite = Sprite::create("HelloWorld.png"sv);
    if (sprite == nullptr)
    {
        problemLoading("'HelloWorld.png'");
    }
    else
    {
        // position the sprite on the center of the screen
        // this should be commented to test anchoring 
        // sprite->setPosition(Vec2(visibleSize.width / 2 + origin.x, visibleSize.height / 2 + origin.y));
        sprite->setAnchorPoint(Vec2(0.5,0.5));

        // add the sprite as a child to this layer
        this->addChild(sprite, 0);

        auto drawNode = DrawNode::create();
        drawNode->setPosition(Vec2(0, 0));

        addChild(drawNode);

        drawNode->drawRect(safeArea.origin, safeArea.origin + safeArea.size, Color4F::BLUE);
    }

[antn9x]

That's not what I need. I want add label to sprite, and then label in center of sprite without set position.

[DelinWorks]

We'll let @rh101 decide what's the right fix for this problem, do you think a setAnchorPointSprite function is any good?

[rh101]

I just read this entire thread. First thing, this engine isn't based on Cocos Creator, but rather on Cocos2d-x v4, so we can't expect the same behaviour of nodes as Cocos Creator. If something isn't working the same as Cocos Creator, it doesn't mean it's a bug in Axmol.

We'll let @rh101 decide what's the right fix for this problem, do you think a setAnchorPointSprite function is any good?

I'm not certain why you think it's my decision for this, but my opinion regarding it is that we shouldn't be introducing custom methods like this. We can add any kind of child node to a another node, so having setAnchorPointSprite doesn't make sense, since it can be any node, and not just a sprite.

Now, regarding this specific issue, the anchor point is not the same as the position. The default position is, I assume, set to 0,0, for any newly created node, and when this is added as a child to another node, it'll be drawn at 0,0, and adjusted based on the anchor point of that child object. You can't get around not setting the position and whatever other methods need to be called.

[DelinWorks]

it's actually a flaw in the engine, instead of moving the vertices of a quad so that it's in the center, the node itself is used to anchor the sprite which is completely wrong and doesn't make sense. it's actually a thing I wanted to point out for so long and because sometimes it becomes infuriating when building UI systems with the current sprite anchoring system, what about making the function setAnchorPoint override the node class and position the sprite vertices accordingly? of course, that would break compatibility but there should be another solution, I asked for your decision/opinion on the function naming and future-proofing the fix, not on whether this fix should exist or not. my bad I didn't clarify.

[rh101]

What you're suggesting is that the 0,0 position of child nodes is in the center of a parent node. Is my understanding of that correct?

What it would do is affect a lot more than just the visual position of the child node. Have you tested the impact it would have on the world position of that child node, and also the target position for touch handling etc.?

when building UI systems with the current sprite anchoring system, what about making the function setAnchorPoint override the node class and position the sprite vertices accordingly?

If sprites are to be used as UI elements with different behavior of the anchor point, then Sprite should sub-classed and a UI system built off that.

Unless I'm not quite understanding what the issue is here, in my opinion, how they work at the moment is correct, and a position of 0,0 on a child sprite should be drawn at the bottom left of the parent node; the child sprite with 0,0 position should not be drawn in the middle of the parent.

[DelinWorks]

I agree with you but for some use cases it's better to have an option in a method that makes you choose what type of anchor you want

[aismann]

Have a look at
cpp-test:
24: Testing Sprite
25. Testing SpriteBatchNode

[antn9x]

I read example code, but not what i need to sprite render by anchor point.

[rh101]

I read example code, but not what i need to sprite render by anchor point.

The behaviour of Cocos2d-x and Axmol is not the same as Cocos Creator. This is not an issue in this engine, and you can't avoid not setting the position.

[aismann]

Try this (answer on cocos2dx forum):

auto parentNode = Node::create();
parentNode->setContentSize(Size(200, 200));

// child
auto sprite = Sprite::create("sample.png");
sprite->setAnchorPoint(Vec2::ANCHOR_MIDDLE);  // (0.5, 0.5)
sprite->setPosition(parentNode->getContentSize() / 2);

parentNode->addChild(sprite);

[aismann]

Here is a working code (setPosition is needed):

        auto sprite = Sprite::create("Images/grossini_dance_08.png");
        sprite->setPosition(Vec2(s.width / 2, s.height / 2));
        addChild(sprite);
        auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);
        label->setPosition(sprite->getPosition());
        addChild(label);

Using an own method can hidden this.

[antn9x]

It should be label->setPosition(sprite-> getContentSize() / 2);

[antn9x]

I did this but it need to use setPosition that is not what i want.

[rh101]

It should be label->setPosition(sprite-> getContentSize() / 2);

No, that's not correct for the snippet of code you're referring to. If you read the code, you will notice that label is not a child of the sprite, but at the same level as the sprite (so both are children of the same parent). That would mean the original code posted is correct, being:
label->setPosition(sprite->getPosition()); (assuming the anchor point of the label is Vec(0.5, 0.5)).

For the first snippet posted by aismann, you'll notice that the label is a child of the sprite, so it correctly has this:
sprite->setPosition(parentNode->getContentSize() / 2);

So, both snippets of code are correct for what they're trying to achieve.

I did this but it need to use setPosition that is not what i want.

What you want and what is correct seem to be clashing here. There is absolutely no bug with the current implementation in this engine. So, once again, you cannot avoid setPosition.

If you want it to behave in the way you keep insisting on, then implement a sub-class of Label, and override all the methods you need to get the functionality you desire.