How to make reflection effect

[SWDmaster]

Take a look at this samples:
[url]http://earthwormjim.free.fr/demo/light_test.htm[/url]
[url]http://www.noisecrime.com/develop/techdemo/dmx/reflectiontest10.htm[/url]

There are reflection on floor and water from other models. We can move and
rotate the camera and the reflection will look real. How can I do the same
effect? May be you have some example. Thank you.

[Michaelcov]

If you are using Max, select a reflection map as well as a diffuse map under
'maps' in the material editor.

The reflection map will export into Director.

This is as far as I got to get it to work so don't ask me how to get it to
look perfect :)

Michael
UK

[SWDmaster]

Thank you.
But using this way we will make only one image reflection. But not reflection from all objects. May be are there ather ways?

[Max]

Do you refer to a real-time reflection simulation like the noisecrime
example?

Max

[jrPace]

From the look of the second example, it looks as though they've simply
duplicated the geometry they want reflected, then mirrored it. By placing a
partially transparent surface where the 'mirror' is, you get the effect of a
reflection.

I assume this is how it was done with this example, I only say this because it
doesn't seem to be inccuring the large frame rate hit involved with rendering
the scene to a texture (as per the first example).

How they did the first example is a bit over my head, but I think the
generally principle is to have a second camera positioned at the mirrored
location between your viewing camera and the water. The render the scene from
this second camera, turn this image into a texture (via imaging lingo, the bit
that inccurs the performance hit), then use this texture in the waters
'reflection' map channel.

Obviously the second approach is far more complicated, and less flexible if
performance is required, but it is dynamic and will reflect the scene even if
it changes. Whereas the first method outlined here would require you to keep
copies of objects you wanted to appear in the reflection, and if and
transformation occurs, apply this to all instances of the model.

Hopefully someone else might be able to explain this better.

Regards
Jonathan Pace
[url]www.unwrong.com[/url]

[Max]

For a second example (real reflection simulation), you write on Dir3d-l
mailing list at:

Email:
[email]Dir3d-l@nuttybar.drama.uga.edu[/email]

Website:
[url]http://nuttybar.drama.uga.edu/mailman/listinfo/dir3d-l[/url]

Bye
Max

[necromanthus]

Jonathan is right.
Two techniques are involved: faked lights (LightMaps) and duplicated models.
Anyway, from certain angles you can figure out the "faked reflection".
cheers

[nick kang]

Off topic, but that last comment is somewhat misleading. Lightmapping is a
form of "static" lighting, meaning the light information is pre-calculated and
not rendered per frame. Lightmaps are usually generated as textures with
level building tools like Radient, Worldcraft or with modelers like 3dsmax
(using the render to texture function). "Fake" seems to imply there is such a
thing as "real" lighting. "Dynamic" lights are calculated per frame, such as
the 4 types of lighting in SW3D, but since these affect fill on a per-vertex
level, the accuracy is dependent on the degree of tesselation (# of triangles)
of the model, usually too low in a real-time scene for a good effect. So if
you have, let's say a torch on the wall, and you want it to cast light on the
walls and floors with a nice dropoff and with shadows, you need to use
something like lightmaps.

Alexx's demos is good example of lightmapping via multitexturing. The sliders
appear to be modifying the intensity of two different lighting maps (textures),
probably via imaging Lingo operations on a bitmap, unless he's got a radiosity
renderer built in there ;-). The wallpaper texture is tiled with a different
set of texture coordinates than the lightmap textures, which is a technique
most games use for static lighting. The geometry is duplicated below the floor
for the reflection effect, but the real point of this demo is the lightmapping.

Noisecrime's reflection demo is entirely different and probably as good as
this effect can get in the current SW3D engine. As Jonathan points outs, there
is a secondary camera rendering the view of the world below the water surface,
mirroring the position of the viewer's camera. This view is mapped to the
water model as a projection (from the viewpoint of the reflection camera).
AFAIK, this mapping has to be done manually, not by using the #reflectionmap
texture channel. Since SW3D doesn't have the ability to render directly to a
texture buffer, a common technique is to place the secondary camera on the
stage and copyPixels() the result into an image object which is assigned to the
water texture (you can see the secondary camera if you point your browser to
the *.dcr file). This needs to be done whenever the viewer's position moves,
which I would have expected to be a big performance bottleneck, but this demo
runs surprisingly well (the SW3D engine and the imaging Lingo engine cannot
share buffers, unfortunately, which is the reason the water texture has to be
kept relatively low res). In addition, he's got mesh deformation to simulate
the water ripples, the texture coordinates are being modified to simulate the
water refraction, and the normals are being regenerated so that the specular is
animated, all this is being done every frame. Since this reflection effect is
dynamic, I would hardly dismiss it as "fake", I thought this demo was pretty
d*mn impressive when I saw it.

[nick kang]

Here's a good diagram describing reflection textures:
[url]http://www.futurenation.net/glbase/reflect.htm[/url]
------------------------
nick * rasterwerks - com

[necromanthus]

Originally posted by: nick kang
Lightmapping is a form of "static" lighting, meaning the light information is
pre-calculated and not rendered per frame.
And this is a faked light !
too much noise for nothing ...