How to generate sprite art assets for different resolution screens?

2
votes

I'm working on a game using OpenGL displaying sprites, i.e. 2d quad-mapped graphics with no projection, that will be displayed on several different resolution screens. (i.e. iPhone retina/non-retina, iPad.. my next project the problem will expand to desktop resolutions which are far more numerous)

I'm OK with handling different aspect ratios, that can be handled by opengl and my placement of the sprites. I'm also OK with slightly different resolutions - use same art and either border the screen, or display a little bit more info.. but when things start to grow/shrink by like 50%+ it's a major issue.

What is standard procedure for generating the art assets in this situation? Generate for the largest resolution and just let OpenGL worry about resizing during it's rasterizing, or do people generate art sets for each main resolution?

Rasterized sprite art tends to get ugly when it's stretched (interpolated), so I'm concerned.. but generating different sizes really means for practical purposes I have to go with vector drawings and export several resolutions. Limits the artist and is somewhat complicated as far as loading and managing the assets

(Yes, I can "just try it" to an extent, but I already have an idea of the results. I'm looking for solutions people use and angles I maybe wouldn't have thought of. This question does have an answer(s) it's not subjective or lazy)

1
graphicsopengl-es2dsprite

1 Answers

3
votes

You are correct that scaling bitmaps tends to make sprites bad. There are a couple of ways of dealing with that:

  1. Draw them (pixelart) at all required resolutions. That is a lot of work but gives you full control.
  2. Draw them (vectors) and render them at all required resolutions. Less work but scaling up or down beyond 50% or 200% might give bad results.
  3. Draw them (3D appliction) and render them at all required resolutions. Quite some work but a very consistent set of sprites.

For each of these options you are free to post-process the bitmaps to clean them up or add details but if you do this for options 2 and 3, you are breaking the chain and will have to apply the changes again when rendering the same set again.

An other option is to limit the variation of resolutions.

As far as I know it is very common in the (game) industry to make all (or the most used/visible) sprites as pixel perfect as possible. This is what they pay the artists for...