Hey Daniel! here it is:
Step 1: Press Ctrl+E or in the dropdown menu select Export... (you can also select Texture Packer)
Step 2: Select Png, Then PRess on the Atlas Setting as in the image below:
Step 3: Create the atlas settings as you wish, then press the Save button in the corner down left.
Step 4: You will be asked to save a json file. Save the json file inside one of the folder of your skins, call the json file pack.json
It should look like this:
Step 5: In my example, I have two folders:
I'll copy and paste the json in the other folder as well.
Step 6: Now we can run Texture Packer. Let's go to the menu (or press Ctrl+P)
Step 7: It's important to choose an export folder that is not inside the folder of images that Spine uses. We can then press Pack
And this is the result! Two separate pngs!
