This package contains everything to draw fec.
The drawing of the outline of a fec object is pretty straight forward.
For the triangles, it's a bit more complicated. Actually, the diffulty comes from the handling of the colMinMax, zMinMax and colOut parameters.
The colMin and colMax values define the colorMap range which is actually used to paint the fec. The color whose index is colMin will be treated as the first color in the colorMap and colMax as the last color.
The zMin and zMax define bounds for the nodes. If the value is oustide the [zMin, zMax] interval it will be painted using one of the outside colors (colOutLow or colOutUp). If inside the interval the color is interpolated between colMin and colMax.
colOutLow and colOutUp define the color to use when the value is outside [zMin, zMax]. If greater than 1, it's a colorMap index pointing to the outside color. If it's -1, the outside part use one of the bounds of the actual colorMap (defines by colMin and colMax). If it is 0, the outside is not painted (transparent).
For more informations about the colors see: http://bugzilla.scilab.org/show_bug.cgi?id=3788.
For rendering, the Fec object actually use the TriangleDecomposition initially developped for color interpolation in GL2PS. It would be faster to use texture as for other interpolation. However, the tricky above parameters, specially the transparency make it difficult to use.