[Papervision3D] Understanding x, y, z, zoom, and focus interaction.
noah at rdai.com
Sat Nov 3 12:53:35 PDT 2007
from a video tutorial that John Grden (one of the core PV3D developers) did,
i found out this magical nugget of info: using the default focal length of
100, and setting the zoom value to 11 will result in a one to one ratio of
display object size to displayed object size.
It helped me, hope it helps you too!
Gregory Sogorka wrote:
> I am trying to wrap my head around the relevance and interaction of
> these values. So it seems to me there are a number of values
> affecting a Camera3D object which when insulated I think I understand.
> But when these values begin to interact with dimension passed to
> constructors such as cubes my understanding becomes a bit hazy.
> Let me be a bit more descriptive:
> 1. I have a cube that I am creating with constant dimensions 100x100x100
> :::: new Cube ( _ml, 100, 100, 100 )
> 2. I have read through the classes for the Camera3D object and think I
> understand the differences between zoom and focus. As the class
> states, the zoom is the scale at which the 3D objects are rendered;
> and the focus is the closest a camera can be to any object.
> Now I have run some tests and rendered the cube and measured it
> dimensions with a pixel ruler tool from Art Directors Toolkit.
> constants throughout my experiment were:
> camera3d.x = 0;
> camera3d.y = 0;
> camera3d.zoom = 2; ( as set by the constructor )
> camera3d.focus = 100; ( as set by the constructor );
> with those constant values I altered the z value of the camera3d
> object and measured the width of the resulting cube:
> z = 50 width = 200;
> z = 75 width = 165;
> z= 100 width = 142;
> z = 125 width = 125;
> z = 150 width = 112;
> z = 175 width = 100;
> So my question is why does the z of 175 result in the actual pixel
> width sent to the cube constructor being rendered on teh screen. I am
> looking for some sort of pattern in the changes but cant seem to
> grasp it. Could anyone help me out with some illumination to this
> simple concept and the broader picture of how all these values
> interact with one another ? or point me to a tutorial that maps these
> things out clearly.
> All the best.
> Papervision3D mailing list
> Papervision3D at osflash.org
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