Here's a quick tutorial on how to use PArray in 3ds Max with the neat grass technique that thxraph put together.
First off, we need to make our plane object that the grass material will be applied to. Now, PArray is very picky about the XYZ orientation of the objects it uses. Even if you change the pivot and align it to 'World', it will ignore it and use the original XYZ orientation that the object was created with. When you create a standard plane, it's Z axis is oriented to it's face's normal, so it will emit from the plane flat to the ground. So, here's what I do in order to make this easer to deal with:
I first create a straight line within the Top viewport (in this case 9" long). I then extruded it approximately 6" - giving me a shape roughly the same size as the maps provided by thxraph. I then applied UVW mapping (it will default map a plane as viewed from the top, so it will have 0 height - so I simply use the Box UVW to simplify things). Then I convert the object to a Poly. So now we have our seed object.
PArray will "spray" particles (or objects) from any type of geometry. So in this case we want it to spray the grass from a plane object (our ground). In this example, I made a 10' x 10' square plane.
So, the first step is to go to the Particle Systems option from the [Create][Object] tab and select PArray. You then draw a box anywhere in the Top viewport (its size does not matter - I don't care what she says....
Now click on the modify tab, and using the below image as reference, I'll walk you through each step.
A. This is the default setting which you want to use for this case.
B. This sets how you will see the objects in the viewport. It won't effect the actual rendering, but I like to set it to Mesh so I can see what's going on. I also set it to 100% so I can see all "particles" so I can guage how much coverage I'm getting.
C. For this case, I'm using a Total ammount for the Particle Quantity, for the same reason as above - I want to see everything all at once.
D. This sets the speed that the particals are being emitted from the plane. This can be either zero or a very low value (zero is better).
E. Particles begin to start emitting at frame 0 (default setting)
F. I set the emit stop at frame 3, meaning after frame 3 all particles have been emitted that I set in step C. You could also set this to 1 if you want.
I forgot to mark it, but you want to set your Grow For and Fade For both to zero.
G. You can adjust the overall size by changing the value in the Size field. In this case I left it at the default. I did set the size variation to 10%, which will randomly resize the grass object by + or - 10% (making the grass a bit rougher).
Unmarked Arrow (oops!). For the particle type, you want to select Instanced Geometry
H. Click on this button, then select the grass object you created earlier.
I. Set the spin time to 1
J. Set the variation to 100%
K. This defaults to Random. Select User Defined
L. Then set the Z axis to 179 degrees (this will let you see both sides - 360 will work as well also).
Then all you need to do is move your time-line slider until you've got a good random rotation of your grass object. In order to create a permanent grass object out of this array, convert the PArray to a poly using the Mesher (found in the Compound Object section)
Piece of cake!
Here's the screenshot of my settings:
_________________"Skill without imagination is craftsmanship and gives us many useful objects such as wickerwork picnic baskets. Imagination without skill gives us modern art." - Tom Stoppard
My modern art gallery at: http://nws.carbonmade.com/