CompuServe Messages

This quaternion (quanternion?) math thingie is why the "rotation" of Cameras and Spotlights are called "Roll" instead of "Rotation." The angle of Roll is the angle away from that needed to keep a line that starts at the center of the Camera (or Spotlight) and passes through it's "bottom center" to keep pointing straight down. It's not the same thing as either an X, Y, or Z Rotation. Remember, Cameras and Spotlights have Targets. Objects don't. You don't Rotate such things because that would affect the positioning of the Targets. This is why I've been suggesting adding "Object Cameras" ever since the WishList freeforall for Release "4." An Object Camera would look to the Renderer as a Camera, but to the Keyframer as an Object (or, more properly, a Dummy). Its visual representation in the Keyframer and 3D Editor screens would be a dashed box (like a Dummy) that is Camera-blue, with a marking of some sort in the center of one face (a circle, perhaps) representing the "lens." It would NOT have a Target and thus would not have Roll keys. Instead, it would have Rotate keys just like any other Object or Dummy. Instead of the Scale keys, it would have FOV keys because in that respect it is still a Camera. It could act as a Parent in heirarchies, with its Children inheriting Position and Rotation just as if it were a Dummy. Perhaps any Objects linked to it would inherit Scale based on the FOV such that they would appear to remain the same size to the Camera as the FOV changed. Such an Object Camera would not have the quaternion singularity movement problem, and could be Keyframed like any other Object. It would not be useful for tracking Objects while changing its position relative to them — for that, you would use the regular Camera. But it would be useful for, say, the viewpoint of a pilot of a plane when the plane is traversing a complex path involving Rotations and Path Follow Banking, yet the pilot also sometimes looks to the left or right etc. relative to the direction of travel.