[vlc-devel] [PATCH 5/5] opengl: limit the fov and zoom to sane values

[Adrien Maglo]

Le 17/11/2016 à 14:06, Steve Lhomme a écrit :
> the zoom translation needs to remain within the sphere
> the field of view should be within 20° and 161°
>
> --
> applies after the previous OpenGL cleaning patches
> ---
>  modules/video_output/opengl.c | 27 +++------------------------
>  1 file changed, 3 insertions(+), 24 deletions(-)
>
> diff --git a/modules/video_output/opengl.c b/modules/video_output/opengl.c
> index 7c0ccb6..5be8449 100644
> --- a/modules/video_output/opengl.c
> +++ b/modules/video_output/opengl.c
> @@ -31,6 +31,7 @@
>
>  #include <assert.h>
>  #include <math.h>
> +#include <float.h>
>
>  #include <vlc_common.h>
>  #include <vlc_picture_pool.h>
> @@ -211,7 +212,6 @@ struct vout_display_opengl_t {
>      float f_roll;
>      float f_fov;
>      float f_zoom;
> -    float f_zoom_min;
>  };
>
>  static inline int GetAlignedSize(unsigned size)
> @@ -449,8 +449,6 @@ vout_display_opengl_t *vout_display_opengl_New(video_format_t *fmt,
>          return NULL;
>      }
>
> -    vgl->f_fov = -1.f; /* In order to init vgl->f_zoom_min */
> -
>      const char *extensions = (const char *)glGetString(GL_EXTENSIONS);
>  #if !USE_OPENGL_ES
>      const unsigned char *ogl_version = glGetString(GL_VERSION);
> @@ -792,30 +790,11 @@ int vout_display_opengl_SetViewpoint(vout_display_opengl_t *vgl,
>                                       const vlc_viewpoint_t *p_vp)
>  {
>  #define RAD(d) ((float) ((d) * M_PI / 180.f))
> -    float f_fov = RAD(p_vp->fov);
> -    if (f_fov > (float) M_PI -0.001f || f_fov < 0.001f)
> -        return VLC_EBADVAR;
> -    if (p_vp->zoom > 1.f || p_vp->zoom < -1.f)
> -        return VLC_EBADVAR;
>      vgl->f_teta = RAD(p_vp->yaw) - (float) M_PI_2;
>      vgl->f_phi  = RAD(p_vp->pitch);
>      vgl->f_roll = RAD(p_vp->roll);
> -
> -    if (fabsf(f_fov - vgl->f_fov) >= 0.001f)
> -    {
> -        /* The fov changed, do trigonometry to calculate the minimal zoom value
> -         * that will allow us to zoom out without seeing the outside of the
> -         * sphere (black borders). */
> -        float sar = (float) vgl->fmt.i_visible_width / vgl->fmt.i_visible_height;
> -        float fovx = 2 * atanf(tanf(f_fov / 2) * sar);
> -        float tan_fovx_2 = tanf(fovx / 2);
> -        float tan_fovy_2 = tanf(f_fov / 2 );
> -        vgl->f_zoom_min = SPHERE_RADIUS / sinf(atanf(sqrtf(
> -                          tan_fovx_2 * tan_fovx_2 + tan_fovy_2 * tan_fovy_2)));
> -    }
> -
> -    vgl->f_fov  = f_fov;
> -    vgl->f_zoom = p_vp->zoom * (p_vp->zoom >= 0 ? 0.5 : vgl->f_zoom_min) * SPHERE_RADIUS;
> +    vgl->f_fov  = RAD( VLC_CLIP(p_vp->fov, 20.f, 161.f) );
> +    vgl->f_zoom = VLC_CLIP(p_vp->zoom, -1.f+FLT_EPSILON, 0.98f) * SPHERE_RADIUS;
>
>      return VLC_SUCCESS;
>  #undef RAD

Why removing the trigonometry calculation? It was giving the exact 
minimal value for the zoom for any SAR and FOVy value.

Best regards,


-- 
MagSoft