[Bug 785980] New: gst_gl_get_affine_transformation_meta_as_ndc (_ext) should use column major matrix

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=785980

            Bug ID: 785980
           Summary: gst_gl_get_affine_transformation_meta_as_ndc (_ext)
                    should use column major matrix
    Classification: Platform
           Product: GStreamer
           Version: 1.12.2
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gst-plugins-bad
          Assignee: gstreamer-bugs at lists.freedesktop.org
          Reporter: HHG01200 at nifty.ne.jp
        QA Contact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---

In gstvideoaffinetransformationmeta.h , it is stated as:
------------------------------------------------------
 * @matrix: the column-major 4x4 transformation matrix
 *
 * are assumed to have an origin at (0.5, 0.5, 0.5) in a left-handed coordinate
------------------------------------------------------

In gstglimagesink.c , it is passed to
gst_gl_get_affine_transformation_meta_as_ndc_ext (af_meta, matrix);

In gstglutils.c , gst_gl_get_affine_transformation_meta_as_ndc_ext() uses
constant matrix, from_ndc_matrix[] and to_ndc_matrix[] .

I think those constant matrices also should be column major.
In addition, I think z axis should be inverted.

------------------------------------------------------
static const gfloat from_ndc_matrix[] = {
// column major, Right Hand -> Left Hand
  0.5f, 0.0f, 0.0, 0.0f,
  0.0f, 0.5f, 0.0, 0.0f,
  0.0f, 0.0f, -0.5, 0.0f,
  0.5f, 0.5f, 0.5, 1.0f,
/*
  0.5f, 0.0f, 0.0, 0.5f,
  0.0f, 0.5f, 0.0, 0.5f,
  0.0f, 0.0f, 0.5, 0.5f,
  0.0f, 0.0f, 0.0, 1.0f,
*/
};

static const gfloat to_ndc_matrix[] = {
// column major, Left Hand -> Right Hand
  2.0f, 0.0f, 0.0, 0.0f,
  0.0f, 2.0f, 0.0, 0.0f,
  0.0f, 0.0f, -2.0, 0.0f,
  -1.0f, -1.0f, -1.0, 1.0f,
/*
  2.0f, 0.0f, 0.0, -1.0f,
  0.0f, 2.0f, 0.0, -1.0f,
  0.0f, 0.0f, 2.0, -1.0f,
  0.0f, 0.0f, 0.0, 1.0f,
*/
};

------------------------------------------------------

I hope experts verify this point.

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