On Wed, 2008-10-15 at 09:17 +0200, Pe'ter, Csa'sza'r wrote:

> I have a problem on "clipping" pango_clutter_render_layout() rendered
> texts. I need to implement actors in a way they do not require open-gl
> clipping since the app I am working on needs to run with Gles<2.0.

Clipping in Clutter works in two ways - either using clip planes or the
stencil buffer. As far as I know, most GLES 1.0 implementations support
clip planes so you might be able to just use the regular cogl_clip_set
functions. Have you tried this?

> I am thinking about rendering text onto a cogl-texture. After that I
> could use cogl_texture_rectangle on it. (It would be even more
> efficient for short constant texts.)

Clutter doesn't yet support FBOs on GLES so it might be a bit tricky to
do this unless, as you said, you reimplement the pango renderer.

I did have a patch to make the pango renderer support rendering to a
clipped rectangle. It worked by clipping each glyph against a rectangle
and munging the coordinates if they spread outside the rectangle. So it
didn't need clip planes or the stencil buffer to work. This was in bug
#833 [1]. However we decided it wasn't necessary because we made the
general clipping work better instead. Do you think this would be useful
anyway?

- Neil

[1] http://bugzilla.openedhand.com/show_bug.cgi?id=833

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