# An attempt to describe vanishingview using 
# CDTree raster in a hypothetical language.
#
# Python-like: syntax includes spaces
# a . b = vector product
# :f(...) = one-directional external function

CDTree(3)

Param
    # the fraction the gap between cells is from the size
    # of the larger one
    float gfrac

    # Alignment point of node at given size
    vec2 :align(node, vec2)

    # the size for node given fraction. 
    # If node is null, return a reasonable constant one
    vec2 :fsize(node, float)

    # Reverse perspective
    float revper

    # Whether cells' sizes should stretch
    boolean varsize

    # How much to shrink cells along different axes
    float shrink0
    float shrink1
    float shrink2

    # The fract of the initial cell
    float initmul

Var
    # The location of a cell
    vec2 v(i)

    # The location of the point of alignment of a cell
    vec2 av(i)

    # The location of a cell, without revper having been applied
    vec2 rv(i)

    # The location of cell's alignpoint, without revper having been applied
    vec2 rav(i)

    # Fraction for the font size
    float fract(i)

    # Size of the cell
    vec2 size(i)	

    # The x and y gaps
    vec2 gap(i)

    # The gap size between two cells.
    vec2 gapb(i,j)

Local(i)
    av(i) = v(i) + :align(i, size(i))
    v(i) = revper * rv(i)
    av(i) = revper * rav(i)

    if(varsize)
	size(i) = :fsize(i, fract)
    else
	size(i) = :fsize(null, fract)

    gap(i) = gfrac * size(i)

Neighbour

    # The shrinking size away from center

    out_0(i,j) => 
	fract(j) = shrink0 * fract(i)
    out_1(i,j) => 
	fract(j) = shrink1 * fract(i)
    out_2(i,j) => 
	fract(j) = shrink2 * fract(i)

    # Propagate the gap to between the cells
    out_*(i,j) => 
	gapb(i,j) = gap(i)


    # The positions of the cells

    pos_0(i,j) =>
	rv(j) . X = v(i) + size(i) . X  + gapb(i,j) . X 
	rav(j) . Y = av(i) . Y

    pos_1(i,j) =>
	rv(j) . Y = v(i) + size(i) . Y  + gapb(i,j) . Y 
	rav(j) . X = av(i) . X

    # We do z axis in a simplistic way until tested
    pos_2(i,j) =>
	rv(j) = v(i) + size(i) + gapb(i,j)

Init
    av(origin) = vec2(0,0)
    fract(origin) = initmul