Improve rotation cache accuracy

In some cases 16.16 precision is not good enough. Instead use 10.22 and
use modulo 360.0 on the angles to make overflows impossible and improve
cache hit ratio sometimes.

diff --git a/libass/ass_render.c b/libass/ass_render.c
index 1dc347f69de07da8bc57d815aa2e39109683195a..22edce81bfdce23bb3046310de8bd85b92b739dc 100644 (file)
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -1915,11 +1915,11 @@ ass_render_event(ASS_Renderer *render_priv, ASS_Event *event,
         text_info->glyphs[text_info->length].hash_key.scale_y =
             render_priv->state.scale_y * 0xFFFF;
         text_info->glyphs[text_info->length].hash_key.frx =
-            render_priv->state.frx * 0xFFFF;
+            rot_key(render_priv->state.frx);
         text_info->glyphs[text_info->length].hash_key.fry =
-            render_priv->state.fry * 0xFFFF;
+            rot_key(render_priv->state.fry);
         text_info->glyphs[text_info->length].hash_key.frz =
-            render_priv->state.frz * 0xFFFF;
+            rot_key(render_priv->state.frz);
         text_info->glyphs[text_info->length].hash_key.fax =
             render_priv->state.fax * 0xFFFF;
         text_info->glyphs[text_info->length].hash_key.fay =

diff --git a/libass/ass_utils.h b/libass/ass_utils.h
index f5c68e96cf634b10405cd6b0d84936dba551f8a7..ad8574c1d69e838053b4595245cd742cfd606e51 100644 (file)
--- a/libass/ass_utils.h
+++ b/libass/ass_utils.h
@@ -102,6 +102,21 @@ static inline int double_to_d16(double x)
 {
     return (int) (x * 0x10000);
 }
+static inline double d22_to_double(int x)
+{
+    return ((double) x) / 0x400000;
+}
+static inline int double_to_d22(double x)
+{
+    return (int) (x * 0x400000);
+}
+
+// Calculate cache key for a rotational angle in degrees
+static inline int rot_key(double a)
+{
+    const int m = double_to_d22(360.0);
+    return double_to_d22(a) % m;
+}
 
 #define FNV1_32A_INIT (unsigned)0x811c9dc5