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The vertices are colored according to their position (-1,1 corresponds to RGB 0,255), and the faces filled in. Note that exactly the same technique can be used to color any solid, though typically extreme positions such as 1 0 0 (i.e. RGB 255 0 0) will not be found.


The J code to produce the graphic follows. vtx is a list of the solid's faces. colorit steps through each face, applying the glVertex and glcolor verbs, to define it as a vertex and as a color.

NB. colored solid
NB. the vertices are colored according to
NB. their position, and the faces filled in.

SOLID=: gscube''    NB. try gsdodecahedron''

GS_ROTXYZ=: 45 60 0
GS_CLEARCOLOR=: 0.1 0 0.2 1

paint=: 3 : 0
face=. 2 pick SOLID
vtx=. 1.5*_3 [\"1 face
clr=. gsfit01 vtx
vtx make_colored"2 clr

colorit=: (glVertex@[ gscolor)"1

make_colored=: 4 : 0
x colorit y
glEnd ''

The same code with cube replaced by icosahedron gives: