diff --git a/Polyhedron/demo/Polyhedron/Scene.cpp b/Polyhedron/demo/Polyhedron/Scene.cpp
index c70929ab4a5e..881f8082f9f9 100644
--- a/Polyhedron/demo/Polyhedron/Scene.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene.cpp
@@ -766,8 +766,14 @@ Scene::draw_aux(bool with_names, CGAL::Three::Viewer_interface* viewer)
       fbos.resize(static_cast<int>(viewer->total_pass()));
       depth_test.resize(static_cast<int>(viewer->total_pass())-1);
 
+      int viewport[4];
+      viewer->glGetIntegerv(GL_VIEWPORT, viewport);
+
+      int w = viewport[2];// viewer->width();
+      int h = viewport[3];// viewer->height();
+
       //first pass
-      fbos[0] = new QOpenGLFramebufferObject(viewer->width(), viewer->height(),QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
+      fbos[0] = new QOpenGLFramebufferObject(w, h, QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
       fbos[0]->bind();
       viewer->glDisable(GL_BLEND);
       viewer->glEnable(GL_DEPTH_TEST);
@@ -781,7 +787,8 @@ Scene::draw_aux(bool with_names, CGAL::Three::Viewer_interface* viewer)
       renderScene(opaque_items, viewer, picked_item_IDs, false, 0,false, nullptr);
       renderScene(transparent_items, viewer, picked_item_IDs, false, 0,false, nullptr);
       fbos[0]->release();
-      depth_test[0] = new QOpenGLFramebufferObject(viewer->width(), viewer->height(),QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
+
+      depth_test[0] = new QOpenGLFramebufferObject(w, h,QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
       depth_test[0]->bind();
       viewer->glDisable(GL_BLEND);
       viewer->glEnable(GL_DEPTH_TEST);
@@ -799,7 +806,7 @@ Scene::draw_aux(bool with_names, CGAL::Three::Viewer_interface* viewer)
       //other passes
       for(int i=1; i<viewer->total_pass()-1; ++i)
       {
-        fbos[i] = new QOpenGLFramebufferObject(viewer->width(), viewer->height(),QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
+        fbos[i] = new QOpenGLFramebufferObject(w, h,QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
         fbos[i]->bind();
         viewer->glDisable(GL_BLEND);
         viewer->glEnable(GL_DEPTH_TEST);
@@ -816,7 +823,7 @@ Scene::draw_aux(bool with_names, CGAL::Three::Viewer_interface* viewer)
         renderScene(transparent_items, viewer, picked_item_IDs, false, i, false, depth_test[i-1]);
         fbos[i]->release();
 
-        depth_test[i] = new QOpenGLFramebufferObject(viewer->width(), viewer->height(),QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
+        depth_test[i] = new QOpenGLFramebufferObject(w, h,QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
         depth_test[i]->bind();
         viewer->glDisable(GL_BLEND);
         viewer->glEnable(GL_DEPTH_TEST);
@@ -832,9 +839,8 @@ Scene::draw_aux(bool with_names, CGAL::Three::Viewer_interface* viewer)
         depth_test[i]->release();
       }
 
-
       //last pass
-      fbos[static_cast<int>(viewer->total_pass())-1] = new QOpenGLFramebufferObject(viewer->width(), viewer->height(),QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
+      fbos[static_cast<int>(viewer->total_pass())-1] = new QOpenGLFramebufferObject(w, h,QOpenGLFramebufferObject::Depth, GL_TEXTURE_2D, GL_RGBA32F);
       fbos[static_cast<int>(viewer->total_pass())-1]->bind();
       viewer->glDisable(GL_BLEND);
       viewer->glEnable(GL_DEPTH_TEST);
diff --git a/Polyhedron/demo/Polyhedron/Triangle_container.cpp b/Polyhedron/demo/Polyhedron/Triangle_container.cpp
index 182f401c04d2..062b3681e1cc 100644
--- a/Polyhedron/demo/Polyhedron/Triangle_container.cpp
+++ b/Polyhedron/demo/Polyhedron/Triangle_container.cpp
@@ -185,8 +185,11 @@ void Triangle_container::draw(Viewer_interface* viewer,
       getVao(viewer)->program->setUniformValue("far", static_cast<float>(viewer->camera()->zFar()));
       getVao(viewer)->program->setUniformValue("writing", viewer->isDepthWriting());
       getVao(viewer)->program->setUniformValue("alpha", d->alpha);
-      if( fbo)
+      if(fbo) {
         viewer->glBindTexture(GL_TEXTURE_2D, fbo->texture());
+        getVao(viewer)->program->setUniformValue("width", fbo->width() * 1.0f);
+        getVao(viewer)->program->setUniformValue("height", fbo->height() * 1.0f);
+      }
     }
     if(getVao(viewer)->program->property("drawLinesAdjacency").toBool())
     {
@@ -225,8 +228,11 @@ void Triangle_container::draw(Viewer_interface* viewer,
       getVao(viewer)->program->setUniformValue("far", static_cast<float>(viewer->camera()->zFar()));
       getVao(viewer)->program->setUniformValue("writing", viewer->isDepthWriting());
       getVao(viewer)->program->setUniformValue("alpha", d->alpha);
-      if( fbo)
+      if(fbo) {
         viewer->glBindTexture(GL_TEXTURE_2D, fbo->texture());
+        getVao(viewer)->program->setUniformValue("width", fbo->width() * 1.0f);
+        getVao(viewer)->program->setUniformValue("height", fbo->height() * 1.0f);
+      }
     }
     if(getVao(viewer)->program->property("isInstanced").toBool())
     {