I've been wondering why Irrlicht and other game systems seem to promote LH coordinates and Y as up instead of Z. To me (and to whomever provided the sample 3D diagram on the Cartesian coordinates system at Wikipedia), Z and RH seem more intuitive.
I figured out how to make Bullet and Irrlicht work my way, but I'm wondering how silly I am to do this.
I'm not loading meshes. I realize I'd have to transform the vertices to get them worked out if I were.
What I haven't been able to find is the general philosophy of this stuff. Why do things one way vs. another?
Thanks much for any help.
Up Vector (Y vs. Z) and LH vs. RH
There may be a more factual/right reason for this, but I think
this has something to do with how 3D computer graphics started out on the computer.
It is simply intuitive to use x,y as coordinates on the screen as you have always done in 2D and use the z coordinate for depth. As in z-Buffer etc.
It also has something to do with the pinhole camera model used extensively throughout cg.
http://en.wikipedia.org/wiki/Pinhole_camera_model
Then someone started to use screen coordinates with x -> right, y ->down and then it got really messy(<- just my opinion) but you get used to it.
It is also strange that in image analysis, the layout of Matrices seems to be column major rather than row major, this is true for OpenGL too, but not for DirectX and most math systems etc.
To me it all seems to be a mess of personal preference, optimizations for computers, ,... and boneheadedness
this has something to do with how 3D computer graphics started out on the computer.
It is simply intuitive to use x,y as coordinates on the screen as you have always done in 2D and use the z coordinate for depth. As in z-Buffer etc.
It also has something to do with the pinhole camera model used extensively throughout cg.
http://en.wikipedia.org/wiki/Pinhole_camera_model
Then someone started to use screen coordinates with x -> right, y ->down and then it got really messy(<- just my opinion) but you get used to it.
It is also strange that in image analysis, the layout of Matrices seems to be column major rather than row major, this is true for OpenGL too, but not for DirectX and most math systems etc.
To me it all seems to be a mess of personal preference, optimizations for computers, ,... and boneheadedness
Well, when you think of a 2D system, X is width and Y is height, right? Well, when you add Z, Z is called depth. So, if you are looking at a given 3 dimensional scene from a logical viewpoint (which would be a person standing on the ground) X is width, or the horizontal axis compared to the viewer. Y is height, or the vertical axis compared the viewer. Z is depth, or the axis that follows the viewer's line of sight.
As for LH vs RH I don't know that one. I like it because I write with my right hand, so if I need to remind myself while I am writing, I can hold up my left hand and keep writing :p
As for LH vs RH I don't know that one. I like it because I write with my right hand, so if I need to remind myself while I am writing, I can hold up my left hand and keep writing :p