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   * Subject: ------=> Sorry NO Subject!
   * Date:    Wednesday, 05 October 1994 17:38:04 [55]
   * From:    Massimiliano Marras (

Another nice use for negative values is the simulation of shadows in scanline mode. Enter Detail Editor, add a ground and a primitive sphere, move the ground along Z axis -160 units. Leave the sphere unchanged but transform it's axis (only) so that has this alignment: X -45,Y 0,Z -90 and the Y axis (only) size is 280 (so that it intersects the ground). Make the sphere a parallel rays, round shape, controlled falloff light source and enter a _negative_ value in the intensity requester that is roughly 75% of the other lightsource's intensity. In this case use -196,-196,-196. Quickrender with a 90 degree horizontal angle and a 45 degree vertical angle. Here you are: istant scanline shadows. Of course you can add softedge lite textures, arrange more negative light sources in order to simulate more complex shapes or even create "shadow volumes" that obscure the object travelling in their area. As long as you use controlled falloff and scale properly the Y axis this trick will not slow the rendering down (controlled lights do not affect objects outside their reach) and will save days of render time compared to raytracing. A good reference about negative lightsources is in Graphics Gems III: "Darklights" by Andrew S. Glassner. Well, i guess Wizard will claim copyright over that book too...

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