axis help?

I am trying to convert a program from c++ to blitz, and am doing a good job, but the program uses a different coordinate system than what Blitz uses. Lucky for me, it has a comment that says that the y axis points left, the z axis points up, and the x axis points into the screen. It also says that it has to convert this axis system from this to DirectDraw's coordinate system, which sounds like blitz's. It just says:


...//screen x = -y simulation
//screen y = z simulation
//screen z = x simulation

How would I go about converting the angles? (what i have done doesn't work, which is exaclty what it says, the same as for direction.) This is probably silly, but can someone help?

It is the common axis system used by many app => like 3dsmax .

you have to operate a -90° rotation on z axis ( from the original axis system ) then a +90° rotation on X axis ( from the original axis system ) , and you'll get the Blitz3D axis system.
But if you want to convert all the original C++ program, maybe you should just use a main pivot that will be parent from all entitys in the scene.
you rotate it from local axis to global axis using the pitch and roll i mentioned, and them, everything will be restored.
( but maybe it's not the best way... )

Thanks bobysait, do I need to do anything for the y axis, or do I just leave it alone? Also, does the z axis (and x) stay the z axis or does it change?

The c++ sim has only one entity, nothing to worry about...

RotateEntity(ent,0,-90,0)?

Sorry guys, but I am not quite understanding this. I have tried to implement both of your ideas but have not been able to do so.

RotateEntity entity\yRot,entity\zRot-90,entity\xRot+90 doesn't seem to help...

x axis points front => should be z
y axis points left => should be x
z axis points up => should be y
Maybe RotateEntity entity\yRot, entity\zRot, entity\xRot ?

Bram, your way works except the picth(my x, sim y) is reversed. It seems to work with negative y:

RotateEntity entity\mesh, -entity\yRot, entitity\zRot, entity\xRot

But after tumbling and spinning a bit, the y becomes reverse (this might be a different problem)

Have you tried setting the optional [global] parameter for RotateEntity to 1 ?

It has always been set to true. I think the problem is that I need to figure out how apply the -y axis to the pitch...

Hmm, and what if you replaced every "x" in the program by "y" and "y" by "z" and "z" by "x" ?
And is it only the "Y" that gets reversed after a while ? Does it get negative ? Are there any ^2 or ABS() operators used ? Or is the Y-angle affected by the other 2 axis ?

Only the y gets reversed, and all of the axis affect each other, meaning the x determines how much the y is and the z also determines how much the y is. (blitz coords)...The x axis should not be touched by the others, but affect the others.


I guess what I am really looking for is a sure way to convert between the axis, because I cannot tell if it is right or if there is a bug. I need to know that the axis conversion stuff is right, and can't think of a way to figure it out.