Fix #132611: EEVEE: Background disappear when using forward shaded volumes

In case forward shaded volumes are used the background can turn black.
This is because in this case an incorrect framebuffer could be bound.

Pull Request: https://projects.blender.org/blender/blender/pulls/132678

source/blender/draw/engines/eevee_next/eevee_pipeline.cc

@@ -78,8 +78,9 @@ void BackgroundPipeline::clear(View &view)
   inst_.manager->submit(clear_ps_, view);
 }
 
-void BackgroundPipeline::render(View &view)
+void BackgroundPipeline::render(View &view, Framebuffer &combined_fb)
 {
+  GPU_framebuffer_bind(combined_fb);
   inst_.manager->submit(world_ps_, view);
 }
 

source/blender/draw/engines/eevee_next/eevee_pipeline.hh

@@ -44,7 +44,7 @@ class BackgroundPipeline {
 
   void sync(GPUMaterial *gpumat, float background_opacity, float background_blur);
   void clear(View &view);
-  void render(View &view);
+  void render(View &view, Framebuffer &combined_fb);
 };
 
 /** \} */

source/blender/draw/engines/eevee_next/eevee_view.cc

@@ -136,7 +136,7 @@ void ShadingView::render()
                                   rt_buffer_opaque_,
                                   rt_buffer_refract_);
 
-  inst_.pipelines.background.render(render_view_);
+  inst_.pipelines.background.render(render_view_, combined_fb_);
 
   inst_.gbuffer.release();