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World Coordinates are not Cartesian

by Jason Cahill · in Torque Game Builder · 04/15/2006 (8:50 am) · 7 replies

OK, I admit it... I'm not the best when it comes to math... and I'll also admit that I've owner T2D for over a year and I'm just noticing this now: the default coordinates are not Cartesian! When you say:

sceneWindow2D.setCurrentCameraPosition("0 0 100 75");

you end up with a screen from (-50, -37.5) in the top-left to (50, 37.5) in the bottom-right. Is there anyway to make T2B use Cartesian coordinates, so I would get:

(-50, 37.5) in the top-left and (50, -37.5) in the bottom-right?

Thanks!
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Torque 3D Owner Tom Perry
#1
04/15/2006 (9:04 am)
I don't know why the y co-ordinates are wrong...I first noticed because it took 1 hour of debugging to work out why my scripts weren't working! I think its the same in GM as well, have to wonder why! :P

Torque Owner Jason Cahill
Default Studio Name
#2
04/15/2006 (11:05 am)
I understand the motivation to have "computer coordinates" as an option. So for example:

sceneWindow2D.setCurrentCameraPosition("50 37.5 100 75");

which will give you a camera space from (0, 0)-(100, 75), which is very "computer friendly." (0, 0) is the top-left.

But, it seems like there should be an equivalent setting for normal "math friendly" coordinates as I mention in my first post.

Torque Owner Jared Coliadis
#3
04/15/2006 (11:42 am)
Off the top of my head: sceneWindow2D.setCurrentCameraArea("0 0 100 75");

Torque Owner Jason Cahill
Default Studio Name
#4
04/15/2006 (11:52 am)
Sorry, but huh? If you read my first post, your example is not cartesian. The Y-axis is reversed.

Torque Owner Jason Cahill
Default Studio Name
#5
04/15/2006 (1:23 pm)
Looking at the sources, the notion of a "normalized rectangle" looks extremely hardcoded.

Melv: Out of curiousity, why did you choose this solution? Is there something about it in particular? Are you just in favor of "computer friendly" coordinates?

Torque Owner Jason Cahill
Default Studio Name
#6
04/15/2006 (1:31 pm)
Also, please don't take my comments as judgemental. I'm not saying that TGB sucks because of this choice. I'm simply curious why this decision was made. The impetus beyond the question is: I'm using Lightwave to do level rendering and layout and having to flip all of the Y coords is a bit of a hassle. At first, nothing was working (everything was upside down). Then, when I figured it out, it was workaroundable, but a minor hassle.

Torque 3D Owner Marc Dreamora Schaerer
Gayasoft
#7
04/16/2006 (6:19 am)
This coordinates are "godgiven" ... (ok not god but computer graphics).

This is due for the simple fact that 0,0 is always top left (beside the windows desktop that behaves nonstandard ) extending to width-1,height-1 on the bottom right.
Choosing the coordinates this way in TGB is a good thing as textures follow that 0,0 - width-1,height-1 as well (as their UVs do)

If you would make it like some geometry teachers and Windows Desktop do and choose the 0,0 at bottom left, then you would end with a lot of recalculation for UV, drawing etc to make it look correct again. processortime you could use for better things, I'm sure :)

Beside that: cartesian coordinates are not fixed as well ... those know as well of left-handed and right-handed which invert a coordinate axis if you switch between those systems. So its a point of view what the "positive" and what "negative" axis alignement is.