Geometry renderer

[barsoosayque]

Summary

SUMMARY: Infrastructure "Decouple rectangle rendering in SDL related code"

Purpose of change

First of all, decoupling and documenting the rendering code. Making it more modular and easier to tweak.

I'm working on a fix for I-am-Erk/CDDA-Tilesets#133, more specifically: rendering a symbol in no sprite for item is found. I need fonts for that, and I can't use them since fonts are using hardcoded static variables and functions from sdltiles.cpp. To decouple fonts, I first need to decouple the mechanism to draw rectangles (since it actually uses two different implementations depending on options user selected).

Describe the solution

Introduce an interface which whole purpose is to render geometry. Use that interface instead of hardcoded functions.

Good:

• Non-intrusive
• Modular
• Easy to understand and use

Bad:

• vtables :(

Describe alternatives you've considered

Maybe using some template magic to reduce usage of virtual stuff. However, I don't think that is going to work, since that one option is known only at runtime, and this option decides what rectangle rendering mechanism to use.

Testing

Loaded up the game, everything works and renders. Color modulated option works. No performance impact is noticed.

[Qrox]

No performance impact is noticed.

Have you tested using debug menu - info - draw benchmark?

[barsoosayque]

Have you tested using debug menu - info - draw benchmark?

I haven't 😓 (Didn't know that was possible). Anyway, yes, the draw benchmark confirms that there is no performance decrease:

On the top is this PR, on the bottom -- master branch