I have needed sometimes merge a list of PNG in one png. Here is a tool usefull for this job. You can export a sequence of png files (with blender, for example) an merge all into a single png.
- Press the "Select Files" Button. Browse your project and select all pngs you want.
- Configure your grid with the options of the right of the tool: with of each frame, height and number of frames per row.
- Press the "Process" Button and select a File.
Your file will be created instantly.
These files are located in addons/spritesheet-from-files
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