atlas texture size vs dimensions

[Mike018]

So the max dimensions of your atlas should be 2048 x 2048 on mobile, but I'm guessing the actual image size is the thing that actually matters, not the dimensions? Mainly because my bitmap font file is bigger than 2048 x 2048, but the size is less than half of my atlases. So I'm wondering if that might be the cause of some crashes and slowness that some devices have been experiencing with my app. So is it dimensions or size that actually matters?

[Antriel]

The actual dimension matters. When the atlas is loaded it's decompressed from whatever format it is (png, jpeg) into pure bitmap (well, some gpus are able to use certain compressions natively, but let's not go there). That means your bitmap font will take exactly the same memory as any other atlas of the same dimensions.

Afaik, the dimensions matter only for GPUs, i.e. webgl mode. They have a certain max size that they support, which makes sense if you think about how GPU works.