FILE: DrawLtrs.txt     SIZE: 3380
DESCRIPTION:  LightWave 3D tip on a method to cause letters in a phrase to 
be revealed one at a time.  One application of this is to have a phrase
"written" by a moving lens flare.

Lightwave Tip

Using a Front Projection Mask to "Draw" Letters.

Have you ever wanted to have letters in a phrase appear one at a time in a
Lightwave animation?  You could model each letter of the phrase individually
and create individual motion paths or transparency envelopes to make the
letters appear, but there's a way that's easier to implement: use a front
projection mask.

In Modeler, create the phrase as a single object and save it as Phrase.lwob.
Put Phrase.lwob in a background layer and create in the foreground a single
rectangular polygon that's slightly larger than Phrase.lwob, just enough to
cover the phrase object.

Reposition the rectangle so that the right edge is at X coordinate 0.  This
puts the pivot point on the right edge. Give the rectangle a surface name of
PhraseMask and save the object as PhraseMask.lwob.

In Layout, create your scene using any objects, lights, or backgrounds you
need EXCEPT for Phrase.lwob.  Leave it out for now.  Render a single frame in
your final output resolution, giving it the name FrontProj.  (It'll get
created as FrontProj001.)

Now load Phrase.lwob and PhraseMask.lwob into your scene.  Position
Phrase.lwob then position PhraseMask.lwob just barely in front of Phrase.lwob
so that it covers it completely.

From the Images panel, load FrontProj001.  From the Surfaces panel, select the
PhraseMask surface and go to the Surface Color Texture Map panel.  Select a
texture type of Front Projection Image Map and select FrontProj001 as the
Texture Image.  Click Use Texture to return to the Surfaces panel.  Set
Luminosity to 100% and all other levels to 0%.  From the Objects panel, turn
off all shadow options for PhraseMask.lwob.

Render the scene.  It should look just like FrontProj001.  PhraseMask.lwob
covers Phrase.lwob and with it's front projection map, it blends perfectly
into the scene.

Now for the magic.  In Layout, select the PhraseMask.lwob object and set a key
frame at zero.  Then go to frame 30.  Using the Stretch tool, set the X size
to zero and set a key frame.  Because the pivot point is on the right edge of
the object, the right edge stays in the same place and the left edge shrinks
toward it.  Make a preview and play it.  You should see the mask object
shrinking over the 30 frames to reveal the Phrase.lwob beneath it.  When you
render and view the animation, the letters seem to appear out of nowhere.

If left alone, it's very likely that the left edge of PhraseMask.lwob will
reveal only part of a letter at some point.  If necessary, you can set key
frames for PhraseMask.lwob so that it always reveals an entire letter at a
time.

Another useful option is to animate a lens flare that moves along with the
left edge of PhraseMask.lwob.  When animated, it looks like the letters are
being written by the flash of light moving across the screen.  The lens flare
also helps hide the sharp edge of the mask.

If you have any questions, email me at P.GODLEY1@GENIE.GEIS.COM or
godley.p@dcc000.ncdcc.cc.nc.us.
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Paul Godley                       Voice: (919)733-7051   Fax: (919)733-0680
NC Dept of Community Colleges     Email: godley.p@dcc000.ncdcc.cc.nc.us
Raleigh, NC
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