cls
DIM FLOAT vertices(2,7) = (-1,1,-1, 1,1,-1, 1,-1,-1, -1,-1,-1, -1,1,1, 1,1,1, 1,-1,1, -1,-1,1)
DIM INTEGER facecount(5)=(4,4,4,4,4,4)
DIM INTEGER faces(23)=(0,1,2,3, 1,5,6,2, 0,4,5,1, 5,4,7,6, 2,6,7,3, 0,3,7,4)
DIM INTEGER colours(6)=(rgb(blue),rgb(green),rgb(yellow),rgb(cyan),rgb(red),rgb(magenta),rgb(yellow))
DIM INTEGER edge(5)=(6,6,6,6,6,6)
DIM INTEGER fill(5)=(0,1,2,3,4,5)
DIM n=1, nv=8, nf=6, camera=1
MATH SCALE vertices(), 100.0, vertices()
DRAW3D CREATE n, nv,nf,camera,vertices(),facecount(),faces(),colours(),edge()',fill()
DIM INTEGER viewplane=500
DRAW3D CAMERA n, viewplane
DIM INTEGER x=0, y=0, z=1000
'PAGE WRITE 1
DRAW3D SHOW n, x, y, z
DIM FLOAT yaw=rad(1), pitch=rad(2), roll=rad(0.5)
DIM FLOAT q(4)
DO
  MATH Q_EULER yaw, pitch, roll, q()
  DRAW3D ROTATE q(),n
  DRAW3D show n,x,y,z
  INC yaw,RAD(1)
  INC pitch,RAD(2)
  INC roll,RAD(0.5)
  'PAGE COPY 1 to 0,B
  pause 25
LOOP

DRAW3D CREATE n, nv,nf,camera,vertices(),facecount(),faces(),colours(),edge()',fill()

DRAW3D SHOW n, x, y, z

DRAW3D SHOW n,x,y,z
[,nocull][,usefurthest]
DRAW3D WRITE n,x,y,z
[,nocull][,usefurthest]

DRAW3D SHOW/WRITE are shown here and are also in the updated The
3D Engine document included in the download.
Rendering of the 3D object works by Painters algorithm. This works by
sorting the faces and drawing those further away first. In addition the
MMBasic firmware supports "back face culling". This doesn't draw faces
that are pointing away from the camera. Setting nocull overrides this and they are drawn.
In order to sort the faces the current
MMBasic code uses the Z axis position of the face centroid. This works in
many situations but in some 3D models it is better to use the furthest vertex
and sort on that. I've added that as an option to DRAW3D SHOW and
DRAW3D WRITE. Set usefurthest to 1 to use the furthest vertex and zero
(default) to use the centroid.

DO
 MATH Q_EULER yaw, pitch, roll, q()
 DRAW3D ROTATE q(),n
 DRAW3D show n,x,y,z,1
 INC yaw,RAD(1)
 INC pitch,RAD(2)
 INC roll,RAD(0.5)
 'PAGE COPY 1 to 0,B
 pause 25
LOOP