Ed,
Just a few explanations for the material settings that are usually important for grass or other objects that are made of planes (2d geometry):
- assume vertical normals: this is normally set on alphachanneled objects that consist of vertical 2d planes (e.g. vegetation). Controls the lighting so that all planes look the same. Important when you have crossed planes like you have on trees. The normals usually face in a horizontal direction to which the texture is visible. the backface, if double sided is darker. Switching to vertical will render the backside as bright as the front side.
- double sided : if true, the plane type object can be seen from both sides (normally you only can see it from the side the normals point to). If you switch this to false the object will be completely transparent from the other side.
- no base material specular: if this is set to true the object will not reflect specular light. It will be flat. This is the setting that makes your object "glare" if you set it to "false" (I guess this is what you meant by glare).
- z-write alpha: the alpha-channel of the object is sorted in the z-buffer. If this is not set other objects with alpha channels, interior structures behind alpha channels (e.g. windows) or clouds etc will be messed up behind the alpha-transparent plane area.
Another important figure is the z-testing parameter (equal, greater, less....) and number, which control the transparency level and the logic according to the grey level of the alpha channel.
Cheers,
Mark