"Alain" <aze### [at] qwertyorg> wrote in message 
news:4bc31c84$1@news.povray.org...

>> "Warp"<war### [at] tagpovrayorg>  wrote in message
>> news:4bbebfde@news.povray.org...
>>> Dre<and### [at] gmailcom>  wrote:
>>>> No it parses correctly, however none of the intersections are correct,
>>>> they
>>>> are all either at<0, 0, 0>  or some weird location.
>>>
>>>   Because you are not shooting the rays towards<0, -1, 0>.
>>>
>>> --
>>>                                                           - Warp
>>
>> I believe I am shooting them in that direction, they are starting at<x, 
>> 10,
>> z>  and finishing at<x, -10, y>, thats towards<0, -1, 0>  in my mind or 
>> am I
>> wrong here?
>>
>> Cheers Dre
>>
>>
>
> You are wrong :(
>
> If you start at <x,10,z> and have a direction of <x,-10,z>, then, you 
> shoot toward <x*2,0, z*2>.
> Remember, the first value is the starting location.
>
> The second value is a *direction* vector, it is ADDED to the start 
> location. If you use a /location/ your tracing rays will fan out.
>
> The result is that most rays, about 75% if the hight_field is around the 
> X-Z plane, will totaly miss the hight_field. Any ray that don't hit the 
> target will return a location of <0,0,0> and a normal of <0,0,0>.
> If the hight_field is a around -10*y, then only 1/16 trace will hit it, at 
> the wrong locations.
>
>
>
> Alain

Yep, the thing that was messing me up was the fact that I thought the second 
value was the final end point not a direction vector.

All sorted now though, thanks for your help!

Cheers Dre

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