On Feb 23, 2016, at 11:37 AM, Miklós Máté <mtmkls at gmail.com> wrote:
>
> It works fine without the tmp context, and Mesa's wgl state tracker doesn't
> do that either. Theoretically wglBindTexImageARB is supposed to be a fast
> render-to-texture method, and creating a new context is anything but fast.
I don't know the history of this code, but there are comments and a FIXME strongly suggesting that, even as is, it doesn't completely work. So, you need to do a thorough investigation for why the code was written this way.
I note that use_render_texture_emulation is always true, these days, so maybe things have changed. I'm not sure why that variable exists.
Also see notes below.
> diff --git a/dlls/winex11.drv/opengl.c b/dlls/winex11.drv/opengl.c
> index 99befde..871cfc1 100644
> --- a/dlls/winex11.drv/opengl.c
> +++ b/dlls/winex11.drv/opengl.c
> @@ -2922,10 +2922,8 @@ static BOOL X11DRV_wglBindTexImageARB( struct wgl_pbuffer *object, int iBuffer )
>
> if (use_render_texture_emulation) {
> static BOOL initialized = FALSE;
> - int prev_binded_texture = 0;
> GLXContext prev_context;
> Drawable prev_drawable;
> - GLXContext tmp_context;
>
> prev_context = pglXGetCurrentContext();
> prev_drawable = pglXGetCurrentDrawable();
> @@ -2940,21 +2938,15 @@ static BOOL X11DRV_wglBindTexImageARB( struct wgl_pbuffer *object, int iBuffer )
> }
>
> TRACE("drawable=%lx, context=%p\n", object->drawable, prev_context);
> - tmp_context = pglXCreateNewContext(gdi_display, object->fmt->fbconfig, object->fmt->render_type, prev_context, True);
> -
> - opengl_funcs.gl.p_glGetIntegerv(object->texture_bind_target, &prev_binded_texture);
>
> /* Switch to our pbuffer */
> - pglXMakeCurrent(gdi_display, object->drawable, tmp_context);
> + pglXMakeCurrent(gdi_display, object->drawable, prev_context);
prev_context is precisely the current context. So, there should be no need to make it current.
>
> - /* Make sure that the prev_binded_texture is set as the current texture state isn't shared between contexts.
> - * After that upload the pbuffer texture data. */
> - opengl_funcs.gl.p_glBindTexture(object->texture_target, prev_binded_texture);
> + /* Upload the pbuffer texture data. */
> opengl_funcs.gl.p_glCopyTexImage2D(object->texture_target, 0, object->use_render_texture, 0, 0, object->width, object->height, 0);
>
> /* Switch back to the original drawable and upload the pbuffer-texture */
> pglXMakeCurrent(gdi_display, prev_drawable, prev_context);
It shouldn't be necessary to "restore" prev_context as the current context, since you never switched to a temporary context. The prev_context and prev_drawable variables should go away entirely.
It seems to me that this entire function boils down to little more than a wrapper around glCopyTexImage2D(). I'm not familiar enough with wglBindTexImageARB() to know if that makes sense.
-Ken