bounding box

eventhorizon02

Hi,
I'm new to Spine so excuse my ignorance......
I'm using the SFML with C++ and the Spine runtimes.
I'm not sure on how to get the bounding box out of my image.
I saw that the SkeletonBox struct has a maxX, minX, maxY, minY members, I tried to use those but I kept getting 0.
It looks fairly easy to set the image position with the SkeletonDrawable class but I can not find a way to get the bounding box for the whole image.
I read somewhere that you have to set up in spine a bounding box for each image separately and then in code combine all the boxes into one general box. Is that the only way? I just need a simple bounding box or rect for simple collision detection or physics movement, etc.
Is there a tutorial somewhere with more details on how to retrieve and manipulate different properties of your runtimes animation?
cheers
🙂

Pharan

I don't think you'd like the results if you had it auto-generate a bounding box from all the individual images.
It would include all the invisible parts of your skeleton and the collisions would not look good nor work intuitively and fairly.
Calculating this all the time incurs some performance cost if you have a lot of images, and it would keep changing the shape, which, depending on your system, would not behave correctly and possibly be updated at a wrong time step.

What you actually could do is just define one big box for your skeleton in Spine, then use that. No need for the many small boxes.
http://esotericsoftware.com/spine-bounding-boxes

Don't be confused with the terminology; the editor's "bounding box" doesn't mean an axis-aligned bounding box. It's actually just a solid 2D polygon.
You can add it on a slot on the root bone so it doesn't move. (as long as the root bone doesn't move). But you can add it on any other bone too.

At runtime, the type is a BoundingBoxAttachment (or spBoundingBoxAttachment in spine-c).

eventhorizon02

Thanks, what if I have to scale my character does the bounding polygon scale as well?

Pharan

It scales like a normal image or mesh. If you scale its bone, or any of its parent/ancestor bones, it will scale.

BinaryCats

^this means you can do super cool stuff with BB's and animations.

eventhorizon02

So in the runtime example code for SFML there is the part that is supposed to change spine boys color when the mouse hovers over it.

I assume that this is how you would use bounding boxes with the run times.
The thing is that it doesn't work in the sample code provided. Is it because the animation was created without bounding boxes or is it a bug in the c api?

ashwani

http://esotericsoftware.com/forum/Spine-Box2d-Skinned-Mesh-5901

Take a look might help u 🙂

Nate

eventhorizon02 wrote
The thing is that it doesn't work in the sample code provided. Is it because the animation was created without bounding boxes or is it a bug in the c api?

Ah, the JSON didn't have the bounding box attachment visible. It's fixed in Git now.

eventhorizon02

Thanks Nate, works good, lasts long time.

Ok, one last question, I promise.
If in spine I have created numerous bounding boxes, how do I access individual boxes by name or by any other means?

Nate

See Skeleton#getAttachment to get an attachment for a slot by name. Also SkeletonBounds#getBoundingBoxes is a list of bounding boxes that are currently visible on the skeleton (update the SkeletonBounds first).