Text Drawing Is Expensive - Possible To Cache Text Drawings?

JeZxLee

Hi,

We are working on a new game using Godot Engine. We made our 1st test build and tested on HTML5 and Android. We are noticing performance issues on Android devices.

Text drawing is rather expensive. Is there any way of putting drawn text into a cache? Draw the text one time and save the drawn text in a texture then draw the texture?

Below is a text cache code(SDL2) we created: https://github.com/SLNTHERO/TetriCrisis_4_110Percent_A.I._Turbo/blob/master/src/visuals.cpp#L1188

Let us know, thanks!

Jesse

TwistedTwigleg

Maybe you could use a Viewport, draw the text in there, and then use the Viewport texture? I'm not sure if it would be better for performance or not, but that's how I'd look at taking a Label and render it into a texture.

Edit: I also think I remember reading that there was improvements to sprite caching, I think, that helped improve text performance. I think I saw it on a Tweet. I'll go see if I can find it and will edit this post if I do.

Edit 2: Found it! I was thinking about sprite batching, which was added in 3.2.4 it seems. Godot blog post Lawnjelly (developer who worked on it) Tweet * GameFromScratch post mentioning the feature

I have no idea if its on by default or not, but if its not on by default than maybe it would improve performance a bit?

Calinou

First, make sure to use the GLES2 renderer when targeting mobile/web platforms. This way, you'll benefit from 2D batching as it's only implemented in GLES2 in Godot 3.2.3. (2D batching will also be available in GLES3 starting from Godot 3.2.4.)

Is there any way of putting drawn text into a cache?

DynamicFont characters are already cached after they're drawn once, but you need to draw each character you plan to use at least once for caching to work. You can do this by creating a Label that displays all the letters/numbers (typically the ASCII) range then hiding it after one frame has passed. (This should be done for each DynamicFont instance you're using.)

In 4.0, DynamicFont preloading will be a built-in feature if this pull request is merged.

JeZxLee

Good stuff, thank you!