Moved the pad offset and aspect ratio to a matrix so it will be added in view space and not in world space

https://bugzilla.gnome.org/show_bug.cgi?id=794401

1 files changed, 14 insertions, 12 deletions

diff --git a/ext/gl/gstglvideomixer.c b/ext/gl/gstglvideomixer.c
index 3879dbb07..6cb5c743b 100644
--- a/ext/gl/gstglvideomixer.c
+++ b/ext/gl/gstglvideomixer.c
@@ -570,6 +570,7 @@ struct _GstGLVideoMixerPad
 
   gboolean geometry_change;
   GLuint vertex_buffer;
+  gfloat m_matrix[16];
 };
 
 struct _GstGLVideoMixerPadClass
@@ -616,6 +617,11 @@ gst_gl_video_mixer_pad_init (GstGLVideoMixerPad * pad)
   pad->blend_function_src_alpha = DEFAULT_PAD_BLEND_FUNCTION_SRC_ALPHA;
   pad->blend_function_dst_rgb = DEFAULT_PAD_BLEND_FUNCTION_DST_RGB;
   pad->blend_function_dst_alpha = DEFAULT_PAD_BLEND_FUNCTION_DST_ALPHA;
+  memset(pad->m_matrix, 0, sizeof(gfloat) * 4 * 4);
+  pad->m_matrix[0] = 1.0;
+  pad->m_matrix[5] = 1.0;
+  pad->m_matrix[10] = 1.0;
+  pad->m_matrix[15] = 1.0;
 }
 
 static void
@@ -1547,16 +1553,11 @@ gst_gl_video_mixer_callback (gpointer stuff)
       w = ((gfloat) pad_width / (gfloat) out_width);
       h = ((gfloat) pad_height / (gfloat) out_height);
 
-      /* top-left */
-      v_vertices[0] = v_vertices[15] =
-          2.0f * (gfloat) pad->xpos / (gfloat) out_width - 1.0f;
-      /* bottom-left */
-      v_vertices[1] = v_vertices[6] =
-          2.0f * (gfloat) pad->ypos / (gfloat) out_height - 1.0f;
-      /* top-right */
-      v_vertices[5] = v_vertices[10] = v_vertices[0] + 2.0f * w;
-      /* bottom-right */
-      v_vertices[11] = v_vertices[16] = v_vertices[1] + 2.0f * h;
+      pad->m_matrix[0] = w;
+      pad->m_matrix[5] = h;
+      pad->m_matrix[12] = (gfloat) pad->xpos / (gfloat) out_width;
+      pad->m_matrix[13] = (gfloat) pad->ypos / (gfloat) out_height;
+      
       GST_TRACE ("processing texture:%u dimensions:%ux%u, at %f,%f %fx%f with "
           "alpha:%f", in_tex, in_width, in_height, v_vertices[0], v_vertices[1],
           v_vertices[5], v_vertices[11], pad->alpha);
@@ -1565,7 +1566,6 @@ gst_gl_video_mixer_callback (gpointer stuff)
         gl->GenBuffers (1, &pad->vertex_buffer);
 
       gl->BindBuffer (GL_ARRAY_BUFFER, pad->vertex_buffer);
-
       gl->BufferData (GL_ARRAY_BUFFER, 4 * 5 * sizeof (GLfloat), v_vertices,
           GL_STATIC_DRAW);
 
@@ -1583,11 +1583,13 @@ gst_gl_video_mixer_callback (gpointer stuff)
     {
       GstVideoAffineTransformationMeta *af_meta;
       gfloat matrix[16];
+      gfloat af_matrix[16];
       GstBuffer *buffer =
           gst_video_aggregator_pad_get_current_buffer (vagg_pad);
 
       af_meta = gst_buffer_get_video_affine_transformation_meta (buffer);
-      gst_gl_get_affine_transformation_meta_as_ndc_ext (af_meta, matrix);
+      gst_gl_get_affine_transformation_meta_as_ndc_ext (af_meta, af_matrix);
+      gst_gl_multiply_matrix4(af_matrix, pad->m_matrix, matrix);
       gst_gl_shader_set_uniform_matrix_4fv (video_mixer->shader,
           "u_transformation", 1, FALSE, matrix);
     }