Frustum culling implementation uses wrong coordinate system

[jfsantos]

Hello,

first of all, thanks for your amazing work on this library!

I am implementing a 3D game using SaturnRingLib and SaturnMathPP and was trying to implement frustum culling and found your implementation. I just noticed that the coordinates you use are not like the ones from SGL. The coordinate system from SGL is (from section 4.1 in the SGL's User Manual):

+X goes right
-Y goes up
-Z goes towards the screen

but in your implementation (from frustum.hpp):

     * Coordinate system:
     * - Uses a right-handed coordinate system where:
     *   - +X is right
     *   - +Y is up
     *   - -Z is forward (into the screen)

Is this intentional or a bug? Since it's not wired into SaturnRingLib yet I could not understand why the coordinate system is different from SGL.

[robertoduarte]

Hi! First of all, thank you so much for using the library!
​You are right to question this. This is happening mainly due to two reasons:
​Independent Development: SaturnMath++ was developed as a standalone library, independent of SRL/SGL. Since it wasn't intended to be an SGL wrapper, I didn't prioritize making the orientation conform to SGL standards at the start.
​Testing Focus: Historically, only the features used within SRL were extensively tested, leaving these orientation discrepancies less explored.
​This has recently become an issue in SRL as we started integrating it into newer examples. The core problem is that Matrix43 is row-major while SGL is column-major. I’ve since realized that column-major is more cache-line efficient, so you can expect a new column-major Matrix34 to be implemented in the near future. This update will also align the coordinate system with SGL, as both legacy and modern tools expect this.
​I’m sorry for the inconvenience; I’m actively working on it, although my free time is currently limited. Thanks for your patience!

[jfsantos]

Please don't apologize, this is amazing work and I'm glad I could leverage it for my game :)

Let me know if I can help somehow. I am getting more familiar with SRL and SaturnMathPP and would love to help test features.