Environment Maps in MaxImmerse
Выдержка из оригинальной справки. (MaxImmerse)
Environment maps are r,g,b maps that are added to the base texture to simulate mirror-like reflection of the environment surrounding the mapped object. Often used with a gloss map, this effect can be very striking, giving a very realistic impression of a mirrored object.
Although any form of texture coordinate mapping may be used with environment maps, almost all environment maps use sphere mapping as their texture coordinate generation method. This is because the pixels in an environment map generally represent the color seen in a given direction in camera space, not at a given position. As a result, environment maps should be mapped using a method that maps direction vectors, rather than positions into the map. In NetImmerse, this is the sphere mapping method.
Note that by default, sphere mapping currently maps from camera space, not world space—as a result, the environment map is assumed fixed to the camera. Each pixel represents a different direction in space. Applications using a rotating camera with environment mapping must be prepared with several environment maps to represent the world as seen from various directions. Since environment maps are added to the base texture, applications must be careful not to use extremely bright images for their environment maps, except in the few pixels that represent directions of specular highlights.
However, some renderers may supply additional functions that allow applications to switch the sphere-mapping behavior from camera-space to world-space. The benefit of such a switch is that it allows applications with moving cameras to use an environment map that is “locked” in world space. As the camera moves around the environment-mapped object, the reflection changes correctly, without any intervention from the application. See the renderer documentation for details on the support (or lack thereof) for this feature.
An object may have only one environment map applied at a time. Currently, if more than one environment map is applied to the same object, any one of the environment maps may be used. Applications should not depend upon any particular behavior in this case, and should avoid it whenever possible.
Environment maps can be used to simulate the reflection of a static environment off of a shiny object or to show different kinds or colors of metal. They can also be used in combination with gloss maps to
specify where the reflections appear (i.e. scuffs on a shiny object will not reflect the environment as much as the polished parts). Environment maps are specified in Max by placing an image in the “Shadow Parameters–> Map” slot of any type of light and checking the "Light Affects Shadow Color" box. The type of light will not have any effect on the environment map.
