Add perspective projection.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@23032 b3059339-0415-0410-9bf9-f77b7e298cf2

diff --git a/libass/ass_render.c b/libass/ass_render.c
index 279a40c40a6bcc82b9d50303f4408934cd742d98..0884f58ce48b27f78328d56e81b2e4c1bba48655 100644 (file)
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -1589,6 +1589,18 @@ static inline void transform_vector_3d(FT_Vector* v, double *m) {
        a[2] = 0.;
        a[3] = 1.;
        transform_point_3d(a, m, b);
+       /* Apply perspective projection with the following matrix:
+          2500     0     0     0
+             0  2500     0     0
+             0     0     0     0
+             0     0     8     2500
+          where 2500 is camera distance, 8 - z-axis scale.
+          Camera is always located in (org_x, org_y, -2500). This means
+          that different subtitle events can be displayed at the same time
+          using different cameras. */
+       b[0] *= 2500;
+       b[1] *= 2500;
+       b[3] = 8 * b[2] + 2500;
        if (b[3] < 0.001 && b[3] > -0.001)
                b[3] = b[3] < 0. ? -0.001 : 0.001;
        v->x = double_to_d6(b[0] / b[3]);