Re: QC fustrum angle

On Tue, Nov 3, 2009 at 1:34 PM, Chris Wood <email@hidden> wrote:

If you really want to do it manually, you'll need to learn some maths.
You need to calculate the distance of a point on a sphere from the
camera (the camera position in QC is (0,0,-1) if I remember right) to
determine size and perspective transform.

I don't understand why you need to convert though - if you have the
xyz position, why not just tell QC to draw your image at that xyz
position?

You could also use the 3D transform patch perhaps?

Chris

2009/11/3 Sune Watts <email@hidden>:
> Sorry if I was unclear:
>
> How to translate an (x, y, z) point into (x, y) screen coordinates --
>
> For example, you have a rotating globe and want to know the screen
> coordinates of a certain city on the globe.
>
>
> Best regards
> Sune Watts
>
>
> ---
>
>
> On Tue, Nov 3, 2009 at 11:02 AM, Chris Wood <email@hidden> wrote:
>>
>> QC supports 3D space already. There's 2 ways to show a 2D image:
>> Billboard (this is best for overlays and the like, and is 2D based)
>> and Sprite (this is similar to billboard, but exists in full 3D space
>> so you can move it on Z, and rotate on all 3 axis.
>>
>> Most likely, sprite will cover your needs.
>>
>> Chris
>>
>>
>> 2009/11/3 Sune Watts <email@hidden>:
>> > Hello all;
>> >
>> > I need to pin a 2D billboard onto a (moving) point in 3D space.
>> >
>> > I haven't been able to find any info on the z-axis scaling QC employs.
>> >
>> > Has anybody got a handle on mathematically converting a point in 3D
>> > space to
>> > 2D screen space?
>> >
>> >
>> > All the best
>> > -SW
>> >
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References:
	>QC fustrum angle (From: Sune Watts <email@hidden>)
	>Re: QC fustrum angle (From: Chris Wood <email@hidden>)
	>Re: QC fustrum angle (From: Sune Watts <email@hidden>)
	>Re: QC fustrum angle (From: Chris Wood <email@hidden>)