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I am using an orthographic camera, so I really need the distance between
a point and the plane formed by the camera's up and right vectors.
Here's my camera definition. Thanks.
Mike
#declare Camera_Diagonal = cosd(45);
#declare Camera_Aspect = image_height / image_width;
#declare Camera_Width = 10240; // was 7680 * 4/3
#declare Camera_Vertical = 225; // was 225
#declare Camera_Horizontal = 30;
#declare Camera_Distance = Camera_Width;
#declare Camera_Up = y * Camera_Diagonal * Camera_Width * Camera_Aspect;
#declare Camera_Right = +x * Camera_Diagonal * Camera_Width;
#declare Camera_Location = z * Camera_Distance;
#declare Camera_Direction = +z * Camera_Distance;
#declare Camera_LookAt = Camera_Location + Camera_Direction;
#declare Camera_Rotate = <Camera_Horizontal,Camera_Vertical,0,>;
#declare Camera_Scale = 4;
#declare Camera_Translate = <0,0,0>;
#declare Camera_Transform = transform
{
rotate Camera_Rotate
scale Camera_Scale
translate Camera_Translate
}
camera
{
orthographic
up Camera_Up
right Camera_Right
location Camera_Location
direction Camera_Direction
transform {Camera_Transform}
}
#declare Camera_Location = vtransform(Camera_Location,Camera_Transform);
#declare Camera_LookAt = vtransform(Camera_LookAt,Camera_Transform);
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VDist(V1, V2). Compute the distance between two points.
Parameters:
V1, V2 = Input vectors.
http://www.povray.org/documentation/view/3.7.1/459/
So, you could either compute the distance between the Camera_Transform[ed]
Camera_Location and Camera_LookAt, or since IIRC the default camera uses a
projection plane one POVunit away from the camera, you could normalize that and
multiply it by the length of the Camera_Distance vector...
Mike Horvath <mik### [at] gmailcom> wrote:
> How do I calculate the distance between a point and the camera? Except,
> I am using an orthographic camera, so I really need the distance between
> a point and the plane formed by the camera's up and right vectors.
Or you could use a Graphics Gems macro to actually calculate the shortest
(perpendicular) distance between the (transformed) camera point and the
(transformed) upright plane.
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From: Mike Horvath
Subject: Re: Calculate distance between point and viewport
Date: 23 Feb 2020 19:55:01
Message: <5e52d895@news.povray.org>



 
 


On 2/23/2020 1:45 PM, Bald Eagle wrote:
>
> VDist(V1, V2). Compute the distance between two points.
> Parameters:
>
> V1, V2 = Input vectors.
>
> http://www.povray.org/documentation/view/3.7.1/459/
>
> So, you could either compute the distance between the Camera_Transform[ed]
> Camera_Location and Camera_LookAt, or since IIRC the default camera uses a
> projection plane one POVunit away from the camera, you could normalize that and
> multiply it by the length of the Camera_Distance vector...
>
No, the first point is somewhere in space and is not connected to the
camera.
> Mike Horvath <mik### [at] gmailcom> wrote:
>> How do I calculate the distance between a point and the camera? Except,
>> I am using an orthographic camera, so I really need the distance between
>> a point and the plane formed by the camera's up and right vectors.
>
> Or you could use a Graphics Gems macro to actually calculate the shortest
> (perpendicular) distance between the (transformed) camera point and the
> (transformed) upright plane.
>
>
The plane doesn't actually have to be the upright plane exactly, but it
does need to be parallel to it and lie somewhere beyond the extents of
the model.
Mike
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Mike Horvath <mik### [at] gmailcom> wrote:
> No, the first point is somewhere in space and is not connected to the
> camera.
>
>
>
> > Mike Horvath <mik### [at] gmailcom> wrote:
> >> How do I calculate the distance between a point and the camera? Except,
> >> I am using an orthographic camera, so I really need the distance between
> >> a point and the plane formed by the camera's up and right vectors.
> >
> > Or you could use a Graphics Gems macro to actually calculate the shortest
> > (perpendicular) distance between the (transformed) camera point and the
> > (transformed) upright plane.
> >
> >
>
> The plane doesn't actually have to be the upright plane exactly, but it
> does need to be parallel to it
OK  that's just the plane equation, IIRC: Ax+By+CzD = 0
Also in F. Lohmueller's analytical geometry include file (Insert Menu?)
and you just set the "offset" from the origin with D.
same as you'd do with plane {z, D}
Then you calculate the distance of the point from that plane.
http://news.povray.org/povray.binaries.images/message/%3Cweb.5880fc4d1652a4dcc437ac910%40news.povray.org%3E/#%3Cweb.588
0fc4d1652a4dcc437ac910%40news.povray.org%3E
> and lie somewhere beyond the extents of
> the model.
That's confusing, since usually the image projection plane is "in front of" all
the stuff  between the camera and the "model", not "beyond the extents" of it.
But I think the link gives you exactly what you need.
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