Planting Some Grass

Revision as of 21:12, 22 January 2008 by Chacal (Talk | contribs)

Of course, no Age is complete without at least a small patch of vegetation.

In this part we will be discussing two techniques:

  • Alpha vertex painting for the patch of grass
  • Billboarding a Bush

Adding a patch of grass

For the patch of grass, we will be using the following texture:
Grass detail.png

The texture has a bit of alpha to make it blend in with the terrain better....

Making a new plane

Bur first we will need a place to place the grass.
We will copy a piece of the floor mesh to place the grass upon.

Enter edit mode on the island surface, and select the faces you want to copy.
Tutorial CopyPlane.png

Now, press Shift-[D] to duplicate the faces.
After that press [P] to extract those duplicated faces into a new mesh of its own.

Exit edit mode, and select the new plane.
Don't forget to shift it up (on the z-axis) by about 0.01 feet (0.01 blender units) to ensure it's not obscured by the islands material itself.

Adding a new material

Of course, it needs a new material. Delete both materials currently assigned, in the Mesh Panel. (Don't worry, it will stay on your island)

Since the new plane has the same UV coordinates as the parent object, you don't need to UV Map it again.
Just add a new material, and set the specularity to 0.0
Now add the grass texture to it. You can set SizeX' and SizeY in the Map-Input tab both to 64 for a nice result.

Vertex painting

Now, go to the Mesh panel, and add a new vertex color layer. Name the new vertex color layer Alpha.
Select the new Vertex color layer by pressing the two buttons left of the name, and start painting the edges of the plane black. Be sure to keep the rest white.
Where the faces of this layer are black, the mesh will become transparent in Uru. Where it is white, it will become opaque. Tutorial VtxPaint.png

Using this technique, you can make the new grass plane blend very nicely with the terrain below it.. Don't forget to paint the first Vertex layer (Col) all white, to get all of the texture on it.

One thing that still needs to be done, is setting the Z-Offset.
The Z-Offset is important to the rendering order.
St it to 2.0 to get a good blend.
Tutorial ZOffset2.png

Suggestions for improvement

You could also find a flower or weed texture, and use a stencil to get it nicely onto this grass, thus adding another bit of realism.

Adding a Bush