Simulating 3D

[Uzibat]

I'm trying to make a 3D rotating shape with a hexagon top (and bottom) and square sides, out of several pictures that I have.

I've managed to get the basic object built but it doesn't pivot around the centre, rather it swings out to one side. Try as I might, I just can't seem to find what code to alter to get it central!

The code is as follows...


global gCorners, gCentre, gRectList, gRotate, gPlane

on startMovie
--initialise lists for shape
initBox
end

on frameScript
gRotate = gRotate - (float(40)/30)*pi()/100

gPlane = - (float(20)/30)*pi/20
drawSides
end

on initBox
--list of corners with x,y and z coordinates
--original corners
corner1 = [-200,-100,-200]
corner2 = [100,-100,-200]
corner3 = [100,100,-200]
corner4 = [-200,100,-200]

--extra corners for making hex top
corner5 = [-100,-300,-200]
corner6 = [-100,300,-200]

--first square drop-down side
corner7 = [-100,300,100] --based on corner5
corner8 = [-100,-300,100] --based on corner6

--second square drop-down side
corner9 = [-200,-100,100] --based on corner1

--third square drop-down side
corner10 = [100,-100,100] --based on corner2

--fourth square drop-down side
corner11 = [100,100,100] --based on corner3

--fifth square drop-down side
corner12 = [-200,100,100] --based on corner4

--new corners for testing

gCorners = [corner1,corner2,corner3,corner4,corner5,corner6,corner7,corner8,corner9,corner10,corner11,corner12]

--the screen centre
gCentre = point(400,350)

--list of sides
gRectList = [[1,2,3,4],[1,5,6,4],[5,6,7,8],[1,5,8,9],[9,10,2,1],[2,3,11,10],[3,4,12,11],[4,6,7,12]]
end

on drawSides
--generate a list of screen points and depths based on the gCorners
--list and the transformation to 2d screen coordinates
list = []
repeat with i = 1 to gCorners.count
temp = plotPoint(gCorners)
add list, temp
end repeat

--create a quad list that takes four points to display a side of the shape
repeat with i = 1 to gRectList.count

--get the four corners
thisRect = gRectList

--get the four screen points to draw
q = [list[thisRect[1]][2],list[thisRect[2]][2], list[thisRect[3]][2],list[thisRect[4]][2]]

--get the closest (depth) screen point
z = min(list[thisRect[1]][1],list[thisRect[2]][1], list[thisRect[3]][1],list[thisRect[4]][1])

--draw the side
sprite(i).quad = q
sprite(i).locZ = z
end repeat
end

on plotPoint objectInfo
--get x,y and z from objectInfo list
x = getAt(objectInfo,1)
y = getAt(objectInfo,2)
z = getAt(objectInfo,3)

--TRANSFORM BY ROTATION AROUND Z

--compute the radius
radius = sqrt(x*x+y*y)

--compute the angle
if x =0.0 then angle = atan(the maxInteger)
else angle = atan(float/x)
if y < 0 then angle = angle + pi()

--rotate
set angle = angle+gRotate

--compute new x,y and z
realX = radius*cos(angle)
realZ = radius*sin(angle)
realY = Z

--TRANSFORM BY ROTATION AROUND X

--compute the radius
radius = sqrt(realY*realY + realZ*realZ)

--compute the angle
if realZ = 0 then angle = atan(the maxInteger)
else angle = (atan(realY/realZ))
if realZ < 0 then angle = angle + pi()

--rotate
angle = angle - gPlane

--compute the new x,y and z
screenX = realX
screenY = radius*sin(angle)
screenZ = radius*cos(angle)

--return both z, and the x and y point
return [screenZ, point(screenX, screenY)+gCentre]
end


8 pictures are then placed in the score and it uses these to build the 3D shape. 2 pictures are used to make the hexagon shape at the top.

Can anyone even give me an idea of what bit of code I'd need to alter?

Thanks

Suzy