Since its inception, cairo-gl has been plagued by the "how am I really supposed to use it?" problem. This lays down my expectations for how cairo-gl will interact with other usage of the GL API. --- src/cairo-gl.h | 26 ++++++++++++++++++++++++++ 1 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/src/cairo-gl.h b/src/cairo-gl.h index 131d114..9efde43 100644 --- a/src/cairo-gl.h +++ b/src/cairo-gl.h @@ -31,6 +31,32 @@ * The Initial Developer of the Original Code is Eric Anholt. */ +/** + * @file cairo-gl.h + * + * The cairo-gl backend provides an implementation of possibly + * hardware-accelerated cairo rendering by targeting the OpenGL API. + * The goal of the cairo-gl backend is to provide better performance + * with equal functionality to cairo-image where possible. It does + * not directly provide for applying additional OpenGL effects to + * cairo surfaces. + * + * Cairo-gl allows interoperability with other GL rendering through GL + * context sharing. Cairo-gl surfaces are created in reference to a + * cairo_device_t, which represents an GL context created by the user. + * When that GL context is created with its sharePtr set to another + * context (or vice versa), its objects (textures backing cairo-gl + * surfaces) can be accessed in the other OpenGL context. This allows + * cairo-gl to maintain its drawing state in one context while the + * user's 3D rendering occurs in the user's other context. + * + * However, as only one context can be current to a thread at a time, + * cairo-gl may make its context current to the thread on any cairo + * call which interacts with a cairo-gl surface or the cairo-gl + * device. As a result, the user must make their own context current + * between any cairo calls and their own OpenGL rendering. + */ + #ifndef CAIRO_GL_H #define CAIRO_GL_H -- 1.7.4.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
