Perhaps you two could dump at the object code for the C and Rb source
and we could see what the differences are.
Charles Yeomans
On Sep 29, 2007, at 3:13 PM, Daniel Stenning wrote:
> This is exactly the issue. And its not as if RS discourages people
> from
> writing 3D Apps in RB. It provides plenty of framework and 3D
> libraries as
> if to encourage people to go down that path.
>
> Out of interest, just how much of that RB 3D app ends up being
> written into
> C++ RB plugins just to get the performance you require ?
>
>
> On 29/9/07 20:02, "Frank Condello" <developer at chaoticbox dot com> wrote:
>
>> ---
>> On 29-Sep-07, at 1:02 PM, Charles Yeomans wrote:
>>
>>> On Sep 29, 2007, at 12:26 PM, Norman Palardy wrote:
>>>>
>>>> What about getting rid of the bitshift ?
>>>>
>>>> i = &h5f375a86 - (i/2)
>>>
>>> I tried this (actually i\2). It saved a few ms, but that's it.
>>
>> Similar results here - it's definitely faster but still slower than
>> the built-in sqrt wrapper.
>>
>> ---
>> On 29-Sep-07, at 1:46 PM, Marco Bambini wrote:
>>
>>> What is fast for you?
>>> I mean, how many Microseconds it should take the FastSqrt
>>> function in
>>> order to be "fast enough"?
>>
>> I'm not measuring a single call. In a real-world 3D app I have to
>> normalize several thousand 3D vectors (among many other things) plus
>> draw everything at (ideally) 60Hz. Normalizing the vectors in C code
>> (loop and all) using an inlined sqrt approximation is far and beyond
>> faster than anything I can muster in RB code - something in the range
>> of 20-30 times faster - no exaggeration. In this case "fast enough"
>> is literally the difference between getting interactive framerates
>> and watching a slideshow.
>>
>> Frank.
>> <http://developer.chaoticbox.com/>
>>
>>
>>
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>
> Cheers,
> Dan
>
>
>
>
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