Image bm865.GIF Light Intensity, Image bm866.GIF Linear Attenuation, Image bm867.GIF Quadratic Attenuation
The point light and spot light can be set by the light intensity, linear attenuation and quadratic attenuation elements. The directional light can be set only by the light intensity. The resulting light intensity versus distance is given by the formula:
brightness = light_intensity / (1 + distance*linear_attenuation + distance^2*quadratic_attenuation)
The light intensity is an additional parameter to set the light color. By setting the light intensity in the range between 0 and 1 a similar effect of light intensity modification can be reached like that attained by the intensity regulation of individual color components of light. By setting the light intensity above 1, a higher light intensity can be reached than it would be possible by mere light color setting. In this manner it is possible to over-light the scene to reach special effects. By setting the light intensity under 0 the so called black light is created. This is a special effect that works as if the light would be "sucked" out of the scene. This effect is utilized when special effects should be reaches, as inverse scotopic vision.

Full Html Context Help of The Peter - Gemtree Software & Children Programming