Detail bending for Vegetation

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To create a tree or bush with both limbs and leaves you need to model at least the trunk and each unique branch. Set up each unique branch to work with the physics as described in Touch_Bending. Instance or copy each branch to complete the model. Attach all objects into 1 editable poly. Now add a VertexPaint modifier to the object.

The following is from with comments for internal artists.

Detail bending for Vegetation Detail bending a vertex color based method to get more natural bending for vegetation. For this tutorial you need a final textured model and an material file.

To show what we want to do, I got this bush.


without detail bending


with detail bending

3D Studio MAX setup Before we start any painting, we have to make sure that we have a clean tessellated mesh.

Like This:


This is wrong. It's too irregular. It will break our bending.


If this is done we have to turn on Vertex Channel Display in Object Properties. Now our object looks like it got no shading. To sea only the vertex color we put on a white material.


Now we assign the first vertex color modifier and paint the whole object black. The first modifier is for the up and down movement of each leaf. For this we use a clear blue. Its very important that we got a 100% clear blue without any red or green. 255 blue means that we got no bending here. 0 blue means strongest bending. So for this object we can select the middle vertexes and turn on soft selection in vertex paint menu. We choose a value so that we got a soft selection all over the object by only selecting the middle vertexes.

Now we give a 255 blue on this selection and got this result:


Now we assign a second vertex color modifier which controls leaves. First we paint all black again. Than we select the outer vertexes of each leaf and paint them 255 red which means here is maximum bending. Then we take the vertexes one more inside and give them a 128 red for lower bending. To get some more variations in this bending we can take some outer vertexes and give them a 220 red. The most important is, keeping the middle line totally black and use only pure red.


Our last color is green. We assign a new vertex color modifier (_don't collapse the other two_)and got to element mode. Now we select our first leaf an paint it green 255 green (again only green, no red nor blue). Than paint the next leaf 220 green, next 190, next 170 and so on. its not important to have exact values, just make sure you use a lot of different greens. This color tell the leafs to start bend in different times, so they don't go up and down all together.


When this is done we set the red and the green vertex paint modifier to "add" mode in the vertex paint dialog. To get this result:


The last step in 3D Studio MAX is to save your work and export the file. Make sure you have a backup before you collapse the stack so you can change if something is wrong in the vertex colors. (Note: You don't have to collapse your stack before exporting)

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