I recently ramped up the level of procedural tree foliage and wanted to briefly post about it. I chose to generate the trees myself and spent some time thinking about how to do that. I didn't look at any other implementations but rather tried to imagine the simplest approach I could think of and build out from there. Initially I considered a tree to simply be a pole (like a telegraph pole). Pointing up, normal to the surface I then imagine rings around its exterior that I could then stitch together using triangles. Next I imagine at some distance along the pole, branching by rotating the (imaginary) pole about the branching point (the new origin) a configurable number of degrees in the XY ZY planes. This process repeats recursively with the pole radius narrowing at each branching point and shortening and effectively produces a hierarchy of transformations (one per branching point) that I then bake into the mesh vertices for each branch sub-mesh. Next, to improve on the rigid pole appearance I modified the ring placement to follow a sinusoidal pattern (rather than the straight pole) by imagining the sin function rotated counter-clockwise +ve 90 degrees in the XY plane. Starting at zero then this function (now transposed) moves vertically upwards and oscillates +/- about the X axis. For the leaves I chose initially a spherical distribution of points. For the spherical distribution of triangular leaves I went with the Fibonacci sphere making each point the leaf triangle's circumcentre.
I then added support for optional hanging vines the colour of which are complementary to the leaf colours.
Finally, for coloration I added support for 3 schemes; Monochrome, Complementary and Analogous coloration (in HSV colour space). A short video of the results can be see in this video: [previewyoutube=FJofx9x1Roo;leftthumb][/previewyoutube]