Re: [Gegl-developer] params of gegl:transform operation

[Michael Henning <drawoc darkrefraction com>]

To use gegl:transform, you need to create the transformation matrix
yourself. There are plenty of tutorials for learning how to create
transformation matrices online.

Then, do this to set the node's property:

1. When you create your matrix, place it in a GeglMatrix3 struct. It
contains one member named coeff, which is a 3x3 array of doubles for
the matrix values.
2. Turn the matrix into a string with gchar* gegl_matrix3_to_string
(GeglMatrix3 *matrix);
3. Set this string as the property "transform" on your gegl:transform
node with gegl_node_set.
4. Free the string from (2) with g_free

Anyway, I hope this helps! Feel free to ask if you have any issues.

  -- drawoc

On Sun, Sep 29, 2013 at 6:06 AM, beee <gdb_1986 163 com> wrote:
>  Hi,
>
> I want to apply perspective effects on an image. But I can't find an
> operation for it. I thought maybe I can do it with gegl:transform. But I
> don't know which parameters should use.
>
> Please help. Thanks!
>
> Regards.
>
>
>
>
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