convert camera position

I have a function from an external lib which takes the following camera parameters:

• x,y,z coordinates for "center of orbit"
• x,y,z vector from "center of orbit" to "camera direction"
• orbital radius
• camera roll

How can I calculate these parameters from the ones I got:

• position vector
• view vector
• zoom min/max
• rota开发者_开发技巧tion angle
• decline angle of the camera

?

And on a related subject: what's a 'camera roll' anyway? Is there somewhere a picture explaining this?

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x,y,z coordinates for "center of orbit"

• I guess this is up to you, let's call it "centerOrbit"

orbital radius

• orbitalRadius = Length(cameraPos - centerOrbit)

x,y,z vector from "center of orbit" to "camera direction"

• (cameraPos - centerOrbit) / orbitalRadius

camera roll

• this could be your "decline angle of the camera" (just guessing again)
• for explanation of what is a camera roll, try googling "yaw pitch roll"