Fri, 28 Nov 2025 by Thomas ten Cate · Comments
Game Development, Around the World
In the previous post, I determined what kind of vegetation should grow where in my procedurally generated world. Now it’s time to actually plant those plants!
As I mentioned last week, I figured out a list of tree species that belong to each “plant functional type” in the BIOME1 system. I made sure to get a set of distinctive-looking trees, so now it was time to fire up Blender, dust off my modelling skills (such as they are) and create some low-poly tree models and an assortment of other plants:
Most of the game takes place at sea, so you won’t often see these models up close. By keeping the polygon count very low, I’m hoping I can render a large enough number of trees without having to resort to impostors. The tallest tree in the back (tonka bean) has only 44 triangles. The simplest plants are just distorted octahedra, with only 8 triangles.
The grasses are generated with Blender’s geometry nodes and are actually way too detailed, with up to 500 triangles each, but I’m not sure I’ll be keeping them anyway. If I do, a handful of intersecting textured planes would be a better implementation.
Inputs
Recall that we have a fairly coarse map of biomes, and that each biome corresponds to a set of plant functional types, each of which contains some plant species. So that indirectly gives us an occurrence map for each species, containing 1.0 where the plant can occur and 0.0 where it can’t.
However, that map only has a resolution of 1×1 km. We don’t want our forest boundaries to be big straight-edged squares, so we’ll have to add some detail to this. In the previous post, I used domain warping to distort the boundaries, because I didn’t want to blend between biome terrain colours. Let’s apply the same trick here, using the same domain warp, so that the plants nicely follow the biome boundaries.
On top of that, I want some artistic control over how often each species appears. For example, in tropical rainforest, most of the visible trees are part of the canopy, but the canopy is occasionally pierced by even taller, so-called “emergent” trees, like the tonka bean we saw above. These should be rarer than the other species, so I’ll give each species a base “occurrence rate”, to be evaluated relative to the other ones in its biome.
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