[3D] - A positive z up-vector using matrix_build_lookat() results in an upside down view

Description

I don't know if this is a bug or intentional, but using matrix_build_lookat() results in an upside down view when using a positive z up-vector. As far as I can remember, in previous GM's (like GM8 or Studio 1), a positive z value used to be the z up vector. Was that changed with Studio 2?

I added the "Contact Us Package" with the sample project here: MatrixBuildLookAt_Z_UpVector.zip

There are a few ways to circumvent this problem:

Use -1 as z up-vector and create your whole game upside down, so that it appears right side up in the game (not ideal)

Invert the FOV and aspect-ratio when building the projection matrix:

var view_mat = matrix_build_projection_perspective_fov(-60, -aspect_ratio, 1, 2000)

Or build your own look-at matrix (included in the sample project)

Expected Change

As mentioned, I don't know if this is intentional or a bug. The expected change would be to have z-positive as up-vector

Steps To Reproduce

Open GameMaker
Create a Camera Object and add it to a Room
Add a Draw Event with the following code:

var camera = camera_get_active();
var aspect_ratio = window_get_width() / window_get_height();

var proj_mat = matrix_build_projection_perspective_fov(60, aspect_ratio, 1, 2000);
var view_mat = matrix_build_lookat(0, 0, 200, room_width / 2, room_height / 2, 0, 0, 0, 1);

camera_set_proj_mat(camera, proj_mat);
camera_set_view_mat(camera, view_mat);

camera_apply(camera);

Run the Game

Now, you obviously have to add something to the room to see the result. I added the link to the sample project in the report description.

How reliably can you recreate this issue using your steps above?

Always

Which version of GameMaker are you reporting this issue for?

2024.4.1 (Monthly)

Which platform(s) are you seeing the problem on?

Windows

Contact Us Package Attached?

[X] I have attached my Contact Us Package

Sample Project Added?

[X] I have included a small sample project

YoYoGames / GameMaker-Bugs