[vlc-devel] [PATCH v2 1/8] viewpoint: add reverse viewpoint function

[Alexandre Janniaux]

Hi,

I don't think it's that more efficient, it even produces exactly the 
same code
in -O0 with gcc.

However, it might be a clearer intent and more idiomatic, thank you for 
the note.

On 2019-03-08 09:33, Steve Lhomme wrote:
> On 3/6/2019 4:31 PM, Alexandre Janniaux wrote:
>> It reverses the transformation (here rotation only) which is helpful 
>> to
>> convert the viewpoint rotation into a world rotation for video 
>> outputs.
>> ---
>>   include/vlc_viewpoint.h | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>> 
>> diff --git a/include/vlc_viewpoint.h b/include/vlc_viewpoint.h
>> index b9e162b02e..7c11c86323 100644
>> --- a/include/vlc_viewpoint.h
>> +++ b/include/vlc_viewpoint.h
>> @@ -59,4 +59,18 @@ static inline void vlc_viewpoint_clip( 
>> vlc_viewpoint_t *p_vp )
>>                             FIELD_OF_VIEW_DEGREES_MAX );
>>   }
>>   +/**
>> + * Reverse the viewpoint rotation.
>> + *
>> + * It can be used to convert a camera view into a world 
>> transformation.
>> + *
>> + * \param vp the viewpoint for which the rotation need to be reversed
>> + */
>> +static inline void vlc_viewpoint_reverse( vlc_viewpoint_t *vp )
>> +{
>> +    vp->yaw   *= -1;
> 
> Wouldn't "vp->yaw = -vp->yaw" be more efficient ?
> 
>> +    vp->pitch *= -1;
>> +    vp->roll  *= -1;
>> +}
>> +
>>   #endif /* VLC_VIEWPOINT_H_ */
>> -- 2.21.0
>> 
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