Image 3d movement

Question

I have some images following each other around in a circular
motion. I want to add a Z dimension so that the images now follow
each other in an eliptical motion, but the images get smaller as
they move into the distance. How can I do this? Here is part of my
current code for the movement:
if gRotateR then
currentangle = currentangle + 2
sprite(me.spriteNum).locH = (sin((currentangle +
pOffset)/57.296) * circleradius) + circlecenter.locH
sprite(me.spriteNum).locV = (cos((currentangle +
pOffset)/57.296) * circleradius) + circlecenter.locV
end if

Answer 1

First, store sprite(me.spritenum) in a property and use that
property instead, so you don't have to keep writing that out:
my = sprite(me.spritenum)
Then add: * 0.5 after circleradius for the locV line, to
change from a circle to an elipse:
my.locV = (cos((currentangle + pOffset)/57.296) *
circleradius
* 0.5) + circlecenter.locV
Also, adjust the sprite's width and height based on a similar
equation to the one you use for your locV:
my.locZ = my.locV
zScale = 1/((-cos((currentangle + pOffset)/57.296) * 0.3)+1)
my.width = my.member.width * zScale
my.height = my.member.height * zScale
And finally you'll probably want to z-sort your sprites based
on their locv:
my.locZ = my.locV
Hope this helps!
- Ben