Alan Gordie:
Last night I was trying to do a disco
ball effect, you know like saturday night fever:)
I made a primitive sphere and scaled
and rotated selected points to make angular patches on the sphere then made it
reflective 90% and put it inside of a box (extruded plane) then aimed two lights
from 2 angles. Ok so far, but......when I render, I can see the reflection of the light on the wall in the sphere, but the light shining off the sphere is not hitting any of the walls...argh
Is this something which Imagine cannot do
or am I doing something wrong?
Curcio Nicholas:
No raytracer (that I know of) can do this.
To reflect lights you need a radiosity raytracer. These aren't too
common and take forever to render scenes.
What you could do is make some sort
of transparency map (or use the transpar.itx texture with something else as
I did with the underwater lighting) and put a light source inside the disco
ball so that the light shines out from the ball.
Goldman:
Actually, it's something ray-tracers
in general can't do. Scenes are rendered opposite to convention. That is, a ray
is traced from the camera to a light, not from the light to the
camera. Therefore, light reflecting off of objects, bouncing, and in
turn hitting other objects is not possible.
A technique exists,
called Radiosity, that attempts to simulate "real-world" lighting effects.
Unfortunately, Imagine (as well as the majority of commercial software on the
market) does not have this rendering capability. It's just as well since
the process is extremely processor intensive (read: takes a loooong amount of
time), though the results can be stunning..
Since 3D visualization is just a simulation
anyway, you can fake the effects with several well placed lights or textures.
I suppose you could make an inner sphere with lots
of holes in it. Stick a point lightsource in this and have the whole
thing rotate. It wouldn't be the best method (points of light would be sharp),
but it would do.
Anyone know what would happen if you
made a sphere totally transparent, but totally reflective? Would a
lightsource (with shadows enabled) pass through it? Would the object look like
glass from the outside (because of the high reflectancy) at the same
time? If so, then take your orignal sphere object, give it 255, 255, 255 filter,
and 255, 255, 255 reflect values. Hopefully, the inner sphere will act as
a gobo/cookie thing while the outer sphere gives the impression of the
disco-ball glass.
Craigh:
Sorry, ray tracing doesn't
work that way (usually)...You need radiosity. The portion of the wall will check
to see if lights are pointed at it when it is being shaded, but will NOT check
to see if REFLECTED light is impinging upon it.One way to do this:
Use Scanline rendering (or ray-tracing, but
make sure the new lights are outside the disco ball if using ray-tracing).
Set up a cluster of multi-colored blinking spotlights inside the disco ball
that rotate with it and point outward.
The original lights will illuminate the
disco ball and the new lights will illuminate the wall with the
spinning/blinking effect seen in your favorite disco-theque! This will also
allow you to use a nice lens flare since the new spinning spot-lights
will occasionally point directly at the camera!
Randy R. Wall:
No Imagine won't bounce light off of
objects (yet). But you could probably make a good fake for it using a Sphere
with the RadWind and Transpar textures. And an axis set to a point source
light inside of the sphere.
I haven't tried this but am sure with some
work it would shoot little squares all over your walls as you rotate your
disco ball. One problem I can think of is you may not be able to have the
nice reflective look that the object you have already tried. But then with
the correct setting it might be possible. Maybe the metal texture set to
chrome on the sphere as well might help?
I'm only gueussing with all of this but
do believe the Transpar texture will be the key to success.
Randy R. Wall:
Well, sense I had nothing else to do I thought I'd
give a quick try at that Disco Ball and see if what I thought would work would.
I think it works pretty nice, but there were a few
things I did not try sense I wanted to post something for you before I hit the
sack.
Anyways, heres what I did for a fairly simple
Disco Ball, but one that still looks and works nice.
- Add a Sphere
- Load the Chrome Attribute
- Add the RadWind texture and set it to:
Radial Scale -1.0 Color 1 R 255.0
Z Scaling 3.0 Color 1 G 0.0
Sweep Division 20.0 Color 1 B 0.0
Fraction 'On' 1.0 Color 2 R 255.0
Dist Travelled 0.0 Color 2 G 255.0
Min Spacing 0.4 Color 2 B 255.0
Max Spacing 0.4 Reflect Adj 1.0
Transparancy 0.0
The colors can be changed to what you like, but its
a good idea to have one a darker color so that when the Transpar texure
lights the walls with the little squares some of them will be darker than
others.. It maybe a good idea if you are going to have a couple of colored
lights hitting the Disco Ball to use a grey color like 100,100,100 for the
dark color and 255, 255, 255 for the lighter color.
Anyways on to the rest of the Disco Ball.
- Now Add the Transpar texture and leave it at the defaults
- Now Add an Axis to the center of the ball and set it to a
Point Source Light and Cast Shodows.
Now your ready to render it.. If you don't have
a lot of things to reflect or lots of glass objects you maybe able to
speed things up by setting the RSDP in prefs to 2. If you do have a lot of
things to render than set it to what need be. But if you want to test out the
Disco ball so you can set it up how YOU like it then I would recomend putting it
in a box with an open end for viewing and set RSDP to 2. This should
work fine for these test.
The only thing I found I didn't like about it
is the squares are all the same distance apart, but the dark and light colors
help break this up a bit as well as having the windows Min & Max Spacing
fairly large. You could make these smaller to make the Ball look a bit better
but I didn't like the sqaures on the walls so close together when I did this.
But then I was testing it in a fairly small box.. I think in a larger box
it might look quite good. Especially if there were other things in the room
for the squares to interact with.. Anyways something for you to play with..
Well I hope you like the looks of it. I tried
the Mosaic texture on it and that looked pretty cool too, but not quite right.
I think these Disc Ball actually have many different shapes on them so
the produce different shapes on the ground. But the Mosaic texture was a bit
to much. I was going to try a combination of a couple of texture, but thought
it would take a while to play around with this and really only wanted
to see how my suggestion would work sense I was only guessing about it. And
sense it did work I figured I'll leave the playing around with the textures for
you..
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