How To Outsmart Your Computer

With the power of MAX you can make all kinds of reflective materials with mapping, but how mirror like are your mirrors?

First lets do the laser test. Make a simple scene with a laser, a mirror to bounce the laser off of, and a surface to have the reflected laser beam hit. (If you don't know how to make a laser beam follow his link: http://www.3dcafe.com/asp/tutorials/max/simplelaser/simplelaser.asp) We know that a mirror will give you good reflections in MAX. Raytrace will follow the light reflected from an object into the reflective surface and to your viewpoint with ease. If you want to bounce light back the other way you need a trick. Finish setting up your laser scene, placing your mirror at a 45 degree angle to the laser beam, and position your other object "around the corner".

Now, turn on your laser and test your mirror......

What you get is a laser beam that disappears into the mirror. The light doesn't bounce. There is no dot on the steel plate. The simple fix: clone your laser light, and move the light source to the point where your original beam hits the mirror. Then rotate the reflected beam into position.

Et Voila!

 

Faking Radiosity in MAX is not too different from bouncing a laser beam. It still requires adding new lights to the scene. The only significant differenc is how much work it takes to get your lights adjusted correctly. Radiosity, in case you forgot, is the light reflected off of an object being reflectined off of other objects near it. If you want an imediate example set a pencil down on a white piece of paper. On the lighted side of the pencil a faint yellow halo should be visible on the paper. If you don't like that example put on a red shirt and stand next to a white wall.

Now you've observed it; here's how you make it in MAX.

The pencil looks good, but if we add a spotlight to cast some radiosity it should look better.

Radiosity could be achieved by mapping all your materials with Reflect/Refract maps set to 6, but lighting will render faster than reflection mapping. To get the radiosity of the pencil onto the paper I placed a free spot in the scene. I made it rectangular and adjusted its size to match the height and length of the pencil. When you place your radiosity light remember to keep shadows turned off. You should also remember that light reflects off of an object at an angle equal to the the angle it came from. Try to position your radiosity light to reflect the angle of your primary light.

As another example of radiosity think of a mirror reflecting onto the wall.

This example works the same way. For this one I used a direct light instead of a spot.

 

The final morsel for this lesson is making a rainbow. You have probably all seen rainbows at one time or another being cast around a room as sunlight shines in through a window with some dangling prism in it. It's a nice effect but even raytraced refraction can't handle the task. Luckily I have Photoshop and an nearly endless supply of spotlights.

Here are the examples of what didn't work. As you can see from the side view, even though MAX provides a prism in its object library the beam of light doesn't get refracted. Infact, the refraction created by the prism object when a raytrace crystal material was applied to it wasn't even useable for the camera view on the right. For my prism I chose instead to extrude a 3 side Ngon (or triangle) and apply the crystal material to that. I set up a free direct light with a volume light effect for visibility. I bet by now you can figure out how I made a rainbow when MAX wouldn't do it for me. I thought about setting up a different light for each color of the spectrum but that seemed like it would require too much fine tuning. The solution here was a single "rainbow" spot with a projection map made in Photoshop.

The omni light gives ambient lighting. The direct light is the "source" for the rainbow. The spotlight is a projector for the spectrum map made with a gradient fill. The result was near perfection.