SpeedTree, Part 3

Continuing from where we left off, I wanted to talk about Zones, Meshes, and Masks. Using mesh zones you can grow your plant life off it’s surface versus from a single point. This works great for ivy and other types of vines. You can then use the same mesh as a mesh force to attract the plant life to it.

There are a couple ways to begin using Zone(s), you click under the “Add” tab and select “Zones-Zone”.


Which gives you an empty Zone that you can attach an imported mesh.


Or when you import a mesh, you get the Mesh Wizard dialogue box asking you how to use the Mesh. If you’re to use it as a Zone, you’ll pick the 3rd choice; “As a surface to grow geometry or proxies from”.


Now it will create a Zone node plus have your mesh attached to it. It’s a subtle difference in the icon.


Speedtree defaults to importing your geometry with the cartesian coordinates with Z up. You just change it to Y up.


Depending on how large your imported geometry, you may need to change the far clipping plane.


Click anywhere in the blue area around your tree nodes to get to the general window.


On the left you will see the main window.


In this dialogue window, under Frustrum-Far Clipping Planes, you can increase the far clip to allow full visibility of  your imported mesh. Like Maya, I usually type in 1 plus 8 zeros.


Now another thing SpeedTree defaults to is working in Triangles. So even if you modeled in Quads, it will default to “tris”. tri_obj

Just switch to “Quads” and you model should look just like it did in your 3d package.quad_obj

If you have a material for your object you can always add it in SpeedTree.


With the mesh and zone added, you just need to add your plant system to to it. I’m using the Kudzu vine as the basis for my wall. I’m testing just the leaf in this example as it’s attached to the zone.


Within the zone towards the bottom of its paramaters. Under “Meshes”” make sure “Enable” is on. The “Include in Model” with include your mesh when you export out. Under Growth, “Area  Influence” attends to spread of distribution based on geometry. When off it seems to cover less density across object. “Adapt to Masks“is selected it will arrange density of plant grown to best grow around the chosen mask. “Surface Adhesion” accounts for objects grown from the “up”direction of the generator (0) and normals of the zone surface (1). It takes some getting used some of these parameters.

Masks can be applied to your plant. The Mask itself is applied to the child of zone. The mask itself is mapped based on the texture coordinate of the parent (zone). So the mask uses the UVs of the mesh you loaded into your zone, but the mask itself is applied to the leave, branch, root, etc. you want it to affect.

I’ve made a loose mask from my wall’s UV layout.

Image converted using ifftoany

Now under the Mask tab, you import it in. Choose how you want it to be utilized under Behavior. Inclusive while grow only within the white area and Exclusive will grow everywhere outside the white area.


Select the child of the zone. This will be where you attach the mask.


Under the Generator tab, scroll towards bottom for the “Masks” input. Your mask will be available in the drop down menu now.


This is the result of your mask on the mesh zone.



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