From cfdccbfed626ca3d2a4b6a00cd9c5995992b5352 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 21 May 2009 16:33:38 +0000
Subject: [PATCH] Fixed handling of case where the master and the slave camera
 are placed on the same GraphisContext, or when the master camera and slave
 camera are assigned to different Camers.  Note normally one doesn't mix
 master with GraphicsContexts and slave cameras so neither case is common.

---
 src/osg/GraphicsContext.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/osg/GraphicsContext.cpp b/src/osg/GraphicsContext.cpp
index 9cb3cd408..16fbb4a63 100644
--- a/src/osg/GraphicsContext.cpp
+++ b/src/osg/GraphicsContext.cpp
@@ -823,6 +823,7 @@ void GraphicsContext::resizedImplementation(int x, int y, int width, int height)
             osg::View* view = camera->getView();
             osg::View::Slave* slave = view ? view->findSlaveForCamera(camera) : 0;
 
+
             if (slave)
             {
                 if (camera->getReferenceFrame()==osg::Transform::RELATIVE_RF)
@@ -853,6 +854,29 @@ void GraphicsContext::resizedImplementation(int x, int y, int width, int height)
                     case(osg::Camera::VERTICAL): camera->getProjectionMatrix() *= osg::Matrix::scale(1.0, aspectRatioChange,1.0); break;
                     default: break;
                 }
+
+                osg::Camera* master = view ? view->getCamera() : 0;
+                if (view && camera==master)
+                {
+                    for(unsigned int i=0; i<view->getNumSlaves(); ++i)
+                    {
+                        osg::View::Slave& child = view->getSlave(i);
+                        if (child._camera.valid() && child._camera->getReferenceFrame()==osg::Transform::RELATIVE_RF)
+                        {
+                            // scale the slaves by the inverse of the change that has been applied to master, to avoid them be
+                            // scaled twice (such as when both master and slave are on the same GraphicsContexts) or by the wrong scale
+                            // when master and slave are on different GraphicsContexts.
+                            switch(policy)
+                            {
+                                case(osg::Camera::HORIZONTAL): child._projectionOffset *= osg::Matrix::scale(aspectRatioChange,1.0,1.0); break;
+                                case(osg::Camera::VERTICAL): child._projectionOffset *= osg::Matrix::scale(1.0, 1.0/aspectRatioChange,1.0); break;
+                                default: break;
+                            }
+                        }
+                    }
+                }
+
+
             }
 
         }