opengl: expose glfmt to public filter

This will allow filters to access the format easily from the callbacks.

modules/video_output/opengl/filter.c

@@ -61,6 +61,9 @@ vlc_gl_filter_New(struct vlc_gl_t *gl, const struct vlc_gl_api *api)
 
     vlc_list_init(&priv->blend_subfilters);
 
+    /* Expose a const pointer to the OpenGL format publicly */
+    filter->glfmt_in = &priv->glfmt_in;
+
     return filter;
 }
 

modules/video_output/opengl/filter.h

@@ -92,6 +92,7 @@ struct vlc_gl_filter {
 
     struct vlc_gl_t *gl;
     const struct vlc_gl_api *api;
+    const struct vlc_gl_format *glfmt_in;
 
     struct {
         /**