begin_gl
Description:
public void begin_gl ()
We do not advise nor reliably support the interleaving of raw GL drawing and Cogl drawing functions, but if you insist, begin_gl and end_gl provide a simple mechanism that may at least give you a fighting chance of succeeding.
Use the CoglGLES2Context api instead
Note: this doesn't help you modify the behaviour of Cogl drawing functions through the modification of GL state; that will never be reliably supported, but if you are trying to do something like:
{
- setup some OpenGL state.
- draw using OpenGL (e.g. glDrawArrays() )
- reset modified OpenGL state.
- continue using Cogl to draw
}You should surround blocks of drawing using raw GL with begin_gl and end_gl:
{
cogl_begin_gl ();
- setup some OpenGL state.
- draw using OpenGL (e.g. glDrawArrays() )
- reset modified OpenGL state.
cogl_end_gl ();
- continue using Cogl to draw
}Don't ever try and do:
{
- setup some OpenGL state.
- use Cogl to draw
- reset modified OpenGL state.
}When the internals of Cogl evolves, this is very liable to break.
This function will flush all batched primitives, and subsequently flush all internal Cogl state to OpenGL as if it were going to draw something itself.
The result is that the OpenGL modelview matrix will be setup; the state corresponding to the current source material will be set up and other world state such as backface culling, depth and fogging enabledness will be sent to OpenGL.
No special material state is flushed, so if you want Cogl to setup a simplified material state it is your responsibility to set a simple source material before calling begin_gl. E.g. by calling set_source_color4ub.
It is your responsibility to restore any OpenGL state that you modify to how it was after calling begin_gl if you don't do this then the result of further Cogl calls is undefined.
You can not nest begin/end blocks.
Again we would like to stress, we do not advise the use of this API and if possible we would prefer to improve Cogl than have developers require raw OpenGL.