From: eugeni <eugeni@b3059339-0415-0410-9bf9-f77b7e298cf2>
Date: Fri, 20 Apr 2007 22:56:42 +0000 (+0000)
Subject: Add perspective projection.
X-Git-Tag: 0.9.7~307
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5a51a3af5e0d1c59afd3382224b85c8d3dff7174;p=libass

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 279a40c..0884f58 100644
--- 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]);