### 3D Parameter Window – OpenGL – View

Fig.: 3D Parameters – View Tab

Here you can define your camera position and orientation: You define your own position including the distance, your up-vector, and optionally an object rotation.

ChaosPro internally of course uses an absolute coordinate system in order to specify your current position. But for your convenience all settings on this tab use a coordinate system relative to your current position.

Now, what does this mean? Of course, better intuitive handling of the settings!
Imagine you are the observer: What do I need to know in order to perfectly define where you are? Well:

1. Your current position (i.e. the position of your head)
2. Where you look at (Viewpoint)
3. Where’s “up” for you, i.e. I need to know the “up”-vector: If you are standing, then the top of your head points towards the sky. If you are lying, it points to some other (horizontal) direction. Got it?

Have a look at the parameter window: You can see the observer position at the bottom of the image: There are three boxes labeled “Viewpoint”, “Observer” (read-only) and “top” (read-only). Your position (“Observer”) cannot be specified directly, instead you adjust your position intuitively by adjusting the sliders “horizontal”, “vertical” and “distance”:

• The horizonal slider lets you rotate your position around your own “horizontal” axis: Simply stretch out your both (left and right) arms: They now define your “own” horizontal axis: If you are standing upright, nothing specular! But if you are lying, then your “horizontal” axis is geared more towards sky direction. Ok, hopefully you’ve understood what I mean: This horizontal slider rotates your own position in (your very own) left-right direction.
• The vertical slider lets you rotate your position in the direction of your “up” vector: So if you are lying, rotating around a vertical angle means (your head points in some horizontal direction in world coordinates!) rotating horizontally (in world coordinates).
• The distance slider lets you modify the distance to your viewpoint in percent.
• The rotation slider (the last in the group) lets you rotate around your view axis.

Now I told you something about rotating and such, but one thing remains to be mentioned: Rotating around what? The sliders rotate not around an artificial “0″ point, no, they rotate around the viewpoint: You specify where you look at, and if you then rotate around horizontally by 45 degree, you rotate around your viewpoint in your own left-right direction by 45 degree.

The viewpoint itself is specified in real-world coordinates.

There are still three sliders labeled “Object Rotation” left to explain: Well, these three sliders let you rotate the fractal object around the world-axis. Normally you won’t use them, so make yourself familiar with all the other settings, and then play around with these sliders.

At the bottom of the window there’s a button labeled “Graphical Positioning”: If you click onto it another window will appear in which you can graphically adjust your position, viewpoint and up-vector. That window is explained in a separate chapter.

And yet another (user friendly) possibility to adjust your position needs to be mentioned: If the OpenGL mode is active and the fractal calculated, you can directly rotate in the fractal window:

• Hold down the left mouse button on the fractal window with the OpenGL fractal inside: While holding down the left mouse button move the mouse left/right to rotate horizontally, move the mouse up/down to rotate vertically.
• Hold down the right mouse button and while holding down move the mouse up/down: This will change the distance.