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Hi
I have figured out a little macro to autocenter an object (see below), but I
would like to auto scale that object to fill x% of the image x and y
dimensions.
I know of image_height and _width and I suspect that the calculation I need
has something to do with the camera angle and other camera params, but I am
not sure how to proceed. Also, I would like this to work for a perspective
camera and an orthographic camera.
I would appreciate some help, thanks
#macro AUTOCENTER(SomeObject)
/*
This macro redeclares the input object so as to do the autocentering
on that object .. see help 3.2.2.8.5 Returning Values Via Parameters
This means that a usage like AUTOCENTER(sphere{whatever} is not legal
- you have to pass in an object.
min_extent is not guaranteed to work with all csg objects.
*/
#local jaMin = min_extent ( SomeObject ); // corner 1
#local jaMax = max_extent ( SomeObject ); // corner 2
#local jax =(jaMin.x+jaMax.x)/2;
#local jay =(jaMin.y+jaMax.y)/2;
#local jaz =(jaMin.z+jaMax.z)/2;
#declare SomeObject = object{SomeObject translate <-jax,-jay,-jaz> }
#end // end of macro
Post a reply to this message
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> Hi
>
> I have figured out a little macro to autocenter an object (see below),
> but I would like to auto scale that object to fill x% of the image x
> and y dimensions.
>
>
> I know of image_height and _width and I suspect that the calculation I
> need has something to do with the camera angle and other camera
> params, but I am not sure how to proceed. Also, I would like this to
> work for a perspective camera and an orthographic camera.
>
> I would appreciate some help, thanks
Orthographic camera: the image scope is given by the right and up
vector's length.
up 1*y
right 1*x
give a 1x1 scene size, stretched over image_height and _width.
Perspective camera: have faith in the maths, for not so narrow angle, you
have a distortion near the border: a circle is not a circle anymore!
Best hint from me: Use the source for the camera ray computation and
reverse the math for some fixed %, assuming a central position of the
object. Or do it the caltech way...
--
This is an unauthorised cybernetic announcement.
When someone says "I want a programming language in which I need only
say what I wish done," give him a lollipop.
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Le Forgeron <jgr### [at] free localhost> wrote:
> Perspective camera: have faith in the maths, for not so narrow angle, you
> have a distortion near the border: a circle is not a circle anymore!
>
> Best hint from me: Use the source for the camera ray computation and
> reverse the math for some fixed %, assuming a central position of the
> object. Or do it the caltech way...
ok, maybe I can reverse the math. But what is the "caltech way"?
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