Block 4900
( fabric.4th -- Console drawing-fabric coordinate machinery )
( FABRIC.md item 4.3.3. 45-degree cavalier orthographic     )
( projection. Z is depth-into-screen, not height. Q48.16    )
( throughout. Raw pixel write (PLOT/FB-WIDTH/FB-HEIGHT) is  )
( C; this capsule is the FORTH-side policy on top of it.    )
46341 CONSTANT COS45  ( Q48.16 cos(45)=sin(45) ~= 0.70710678 )
VARIABLE ZD
: Z->DELTA ( z -- delta )
  Q.FROM-INT COS45 Q.* Q.TO-INT ;

Block 4901
( PROJECT: 3D Cartesian (x y z) -> 2D Cartesian (sx sy).    )
( Cavalier projection: depth pushes diagonally up-right.    )
: PROJECT ( x y z -- sx sy )
  Z->DELTA ZD !
  ZD @ +
  SWAP ZD @ +
  SWAP ;
( CART-Y: Cartesian Y (origin bottom, up positive) ->       )
( raster Y (origin top, down positive). The Y-flip.         )
: CART-Y ( cart-y -- raster-y )
  FB-HEIGHT 1- SWAP - ;

Block 4902
( CART-PLOT: full pipeline -- 3D Cartesian point to screen. )
: CART-PLOT ( x y z color -- )
  >R
  PROJECT
  CART-Y
  R>
  PLOT ;