GameMaker 3D Issues with camera

[FireflyX91]

Hello Gamemakers, I'm currently working on a 3D project and I've ran into a couple of issues that I can't seem to solve so I was hoping somebody would take a look at my code and help me out.

The problem is that my camera is displaying the world upside down. I believe this is due to GMS2 displaying the Z axis the opposite way to previous versions of GM. However I don't know how to modify this code to display it correctly. The code below was actually taken from an older version and I've had to replace all the d3d functions with their newer equivalents.

This is what I have in my camera objects "Create" event:

view_enabled = true;
view_set_visible(0,true);

var aspect = view_get_wport(0) / view_get_hport(0);   

camera = camera_create();

projection_matrix = matrix_build_projection_perspective_fov(45,aspect,1,32000);
camera_set_proj_mat(camera,projection_matrix);

view_set_camera(0,camera);

camera_set_update_script(camera,scr_cam_update);

The camera update script "scr_cam_update" is most likely the source of the problem:

var cam_x = obj_char.x;
var cam_y = obj_char.y;
var cam_z = obj_char.z + obj_char.height;
var cam_dir = obj_char.direction;
var cam_pitch = obj_char.pitch;

var matrix = matrix_build_lookat(
    cam_x,cam_y,cam_z,
    cam_x + lengthdir_x(1, cam_dir),
    cam_y + lengthdir_y(1, cam_dir),
    cam_z + lengthdir_y(1, cam_pitch),
    0,0,1
    );
    
camera_set_view_mat(view_camera[0],matrix);

Thanks for taking the time to view this thread and I hope somebody can point me in the right direction.

 

[Kobold]

change this

projection_matrix = matrix_build_projection_perspective_fov(45,aspect,1,32000);

to that:

projection_matrix = matrix_build_projection_perspective_fov(-45,-aspect,1,32000);

 

[FireflyX91]

That was even simpler than I thought and it now does what I need. Thanks for your help with that