[FFmpeg-devel] [PATCH 4/4] lavfi/vf_v360: implement output mask for barrelsplit

[Anton Khirnov <anton@khirnov.net>]

The top/bottom of the barrel are each coded as two semicircles inside a
square block in the frame. Mask out the parts of the square that lie
outside of these semicircles, so they are made transparent when
alpha_mask=1.

Fixes the other part of #9725.
---
 libavfilter/vf_v360.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index 940e6fc5f6..42b1761333 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -3745,6 +3745,7 @@ static int barrelsplit_to_xyz(const V360Context *s,
     const float x = (i + 0.5f) / width;
     const float y = (j + 0.5f) / height;
     float l_x, l_y, l_z;
+    int ret;
 
     if (x < 2.f / 3.f) {
         const float scalew = s->fout_pad > 0 ? 1.f - s->fout_pad / (width * 2.f / 3.f) : 1.f - s->out_pad;
@@ -3763,6 +3764,8 @@ static int barrelsplit_to_xyz(const V360Context *s,
         l_x = cos_theta * sin_phi;
         l_y = sin_theta;
         l_z = cos_theta * cos_phi;
+
+        ret = 1;
     } else {
         const float scalew = s->fout_pad > 0 ? 1.f - s->fout_pad / (width  / 3.f) : 1.f - s->out_pad;
         const float scaleh = s->fout_pad > 0 ? 1.f - s->fout_pad / (height / 4.f) : 1.f - s->out_pad;
@@ -3788,13 +3791,14 @@ static int barrelsplit_to_xyz(const V360Context *s,
         l_x = (0.5f - uf) / scalew;
         l_y =  0.5f * dir_vert;
         l_z = (vf - 0.5f) * dir_vert / scaleh;
+        ret = (l_x * l_x * scalew * scalew + l_z * l_z * scaleh * scaleh) < 0.5f * 0.5f;
     }
 
     vec[0] = l_x;
     vec[1] = l_y;
     vec[2] = l_z;
 
-    return 1;
+    return ret;
 }
 
 /**
-- 
2.34.1

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