Fix anti-aliasing on macOS

Blitting to the resolve FBO in OSG::RenderStage was causing a GL_INVALID_FRAMEBUFFER_OPERATION due to a mismatch in attached colorbuffers between the FBOs bound in read and draw slots. This was because the normal attachment was invariantly attached to FBO_Interrupt, but not to other FBOs.

Author: thagberg

apps/openmw/mwrender/postprocessor.cpp

@@ -503,6 +503,7 @@ namespace MWRender
         if (mSamples > 1)
         {
             fbos[FBO_Multisample] = new osg::FrameBufferObject;
+            fbos[FBO_Intercept] = new osg::FrameBufferObject;
             auto colorRB = createFrameBufferAttachmentFromTemplate(
                 Usage::RENDER_BUFFER, width, height, textures[Tex_Scene], mSamples);
             if (mNormals && mNormalsSupported)
@@ -511,6 +512,8 @@ namespace MWRender
                     Usage::RENDER_BUFFER, width, height, textures[Tex_Normal], mSamples);
                 fbos[FBO_Multisample]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER1, normalRB);
                 fbos[FBO_FirstPerson]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER1, normalRB);
+                fbos[FBO_Intercept]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER1,
+                    Stereo::createMultiviewCompatibleAttachment(textures[Tex_Normal]));
             }
             auto depthRB = createFrameBufferAttachmentFromTemplate(
                 Usage::RENDER_BUFFER, width, height, textures[Tex_Depth], mSamples);
@@ -519,11 +522,8 @@ namespace MWRender
                 osg::FrameBufferObject::BufferComponent::PACKED_DEPTH_STENCIL_BUFFER, depthRB);
             fbos[FBO_FirstPerson]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER0, colorRB);
 
-            fbos[FBO_Intercept] = new osg::FrameBufferObject;
             fbos[FBO_Intercept]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER0,
                 Stereo::createMultiviewCompatibleAttachment(textures[Tex_Scene]));
-            fbos[FBO_Intercept]->setAttachment(osg::FrameBufferObject::BufferComponent::COLOR_BUFFER1,
-                Stereo::createMultiviewCompatibleAttachment(textures[Tex_Normal]));
         }
         else
         {