Images and fonts

If a shape will do, use a shape: it has no file, no memory cost and no rights question. Make an image the size of its place on screen, no more than 2048 for a mobile level and 4096 overall

Round the image size up to a power of two

Formats and size

Anything the engine can decode from a file's bytes loads. In practice that is png and jpg

The game puts no limit on the file size, the hardware does:

Memory

The real limit is memory. In memory an image is stored as raw pixels, however much the file weighs. A png takes 4 bytes per pixel. A jpg takes 3, because it has no transparency

What the player decides

Three items in every player's graphics settings decide how much memory an image takes:

• whether images are compressed on load. Compression divides the numbers above by 4-8
• the largest side of an image in memory. Half the side - a quarter of the memory
• whether to build mip-maps, reduced copies for drawing small

A phone compresses images and caps them at 2048 by default. A desktop PC keeps the full image and caps it at 4096

Your part is the fields on the image, first of all what it depicts. They sit next to the image in the resources list. A photograph survives scaling down and compression best. A drawing with hard edges survives them worse

Pixel Art never gets mip-maps, whatever the device would prefer. It also starts out uncompressed and unsmoothed, and the Compression and Sampling fields can change that

Mip-maps

Mip-maps stop a small image from shimmering. They are reduced copies drawn instead of the full image while it is small on screen. They cost a third more memory

Without mip-maps a scaled-down image does not smooth out, it ripples. A player can turn them off, and Pixel Art never gets them

A 4096 image that takes 200 pixels on screen costs 256 times the memory of the same image scaled down to 256 in advance

Shapes before images

A shape is cheaper than an image in every way: no file, no memory, no rights question. Built-in shapes are real geometry, not a picture on a rectangle. They have no transparent margins that get drawn and thrown away

This shows on a phone. On a mid-range mobile chip a scene of 1000 objects spends 95-97% of the GPU's time shading pixels. A shape covers 29.4% of its rectangle. The rest of a textured quad is transparent waste

An image is needed when you need exactly a picture: a logo, a photograph, hand-drawn art. For a geometric form, take a shape. If the one you need does not exist, draw it in the Shape editor

Fonts

Fonts load as ttf, otf, ttc. With no font of its own, text is drawn with whatever the system has, and that differs between devices

The Font Cache is the set of characters prepared for drawing in advance. A generator rebuilds it from the text the level contains. Run the generator once the text stops changing

Next: Level budget, Mobile devices