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

[Steve Lhomme]

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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