rendering: add device-pixel-ratio traversal state

include/Inventor/SoRenderManager.h

@@ -166,6 +166,8 @@ class COIN_DLL_API SoRenderManager {
 
   void scheduleRedraw(void);
   void setWindowSize(const SbVec2s & newsize);
+  void setDevicePixelRatio(float dpr);
+  float getDevicePixelRatio(void) const;
   const SbVec2s & getWindowSize(void) const;
   void setSize(const SbVec2s & newsize);
   const SbVec2s & getSize(void) const;

include/Inventor/SoSceneManager.h

@@ -75,6 +75,8 @@ class COIN_DLL_API SoSceneManager {
   virtual SoNode * getSceneGraph(void) const;
   void setWindowSize(const SbVec2s & newsize);
   const SbVec2s & getWindowSize(void) const;
+  void setDevicePixelRatio(float dpr);
+  float getDevicePixelRatio(void) const;
   void setSize(const SbVec2s & newsize);
   const SbVec2s & getSize(void) const;
   void setOrigin(const SbVec2s & newOrigin);

include/Inventor/elements/SoDevicePixelRatioElement.h

@@ -0,0 +1,35 @@
+#ifndef COIN_SODEVICEPIXELRATIOELEMENT_H
+#define COIN_SODEVICEPIXELRATIOELEMENT_H
+
+/**************************************************************************\
+ * Copyright (c) 2026 The Coin3D contributors                          *
+ *                                                                        *
+ * This file is part of Coin.                                            *
+ *                                                                        *
+ * Coin is free software; you can redistribute it and/or modify it under *
+ * the terms of the GNU General Public License as published by the Free  *
+ * Software Foundation; either version 2 of the License, or (at your      *
+ * option) any later version.                                            *
+\**************************************************************************/
+
+#include <Inventor/elements/SoFloatElement.h>
+
+class COIN_DLL_API SoDevicePixelRatioElement : public SoFloatElement {
+  typedef SoFloatElement inherited;
+
+  SO_ELEMENT_HEADER(SoDevicePixelRatioElement);
+
+public:
+  static void initClass(void);
+
+  void init(SoState * state) override;
+
+  static void set(SoState * state, SoNode * node, float dpr);
+  static void set(SoState * state, float dpr);
+  static float get(SoState * state);
+
+protected:
+  ~SoDevicePixelRatioElement() override;
+};
+
+#endif // !COIN_SODEVICEPIXELRATIOELEMENT_H

include/Inventor/elements/SoElements.h

@@ -86,6 +86,7 @@
 #include <Inventor/elements/SoComplexityElement.h>
 #include <Inventor/elements/SoCreaseAngleElement.h>
 #include <Inventor/elements/SoDecimationPercentageElement.h>
+#include <Inventor/elements/SoDevicePixelRatioElement.h>
 #include <Inventor/elements/SoFocalDistanceElement.h>
 #include <Inventor/elements/SoFontSizeElement.h>
 #include <Inventor/elements/SoLineWidthElement.h>

src/actions/SoGLRenderAction.cpp

@@ -80,6 +80,7 @@
 #include <Inventor/elements/SoCacheElement.h>
 #include <Inventor/elements/SoDecimationPercentageElement.h>
 #include <Inventor/elements/SoDecimationTypeElement.h>
+#include <Inventor/elements/SoDevicePixelRatioElement.h>
 #include <Inventor/elements/SoGLCacheContextElement.h>
 #include <Inventor/elements/SoGLLazyElement.h>
 #include <Inventor/elements/SoGLLightIdElement.h>
@@ -644,6 +645,7 @@ SoGLRenderAction::initClass(void)
 
   SO_ENABLE(SoGLRenderAction, SoDecimationPercentageElement);
   SO_ENABLE(SoGLRenderAction, SoDecimationTypeElement);
+  SO_ENABLE(SoGLRenderAction, SoDevicePixelRatioElement);
   SO_ENABLE_LEGACY_GL(SoGLRenderAction, SoGLLightIdElement);
   SO_ENABLE_LEGACY_GL(SoGLRenderAction, SoGLRenderPassElement);
   SO_ENABLE_LEGACY_GL(SoGLRenderAction, SoGLUpdateAreaElement);

src/elements/CMakeLists.txt

@@ -22,6 +22,7 @@ set(COIN_ELEMENTS_FILES
 	SoCullElement.cpp
 	SoDecimationPercentageElement.cpp
 	SoDecimationTypeElement.cpp
+	SoDevicePixelRatioElement.cpp
 	SoDepthBufferElement.cpp
 	SoDiffuseColorElement.cpp
 	SoDrawStyleElement.cpp

src/elements/SoDevicePixelRatioElement.cpp

@@ -0,0 +1,51 @@
+/**************************************************************************\
+ * Copyright (c) 2026 The Coin3D contributors                          *
+ *                                                                        *
+ * This file is part of Coin.                                            *
+ *                                                                        *
+ * Coin is free software; you can redistribute it and/or modify it under *
+ * the terms of the GNU General Public License as published by the Free  *
+ * Software Foundation; either version 2 of the License, or (at your      *
+ * option) any later version.                                            *
+\**************************************************************************/
+
+#include <Inventor/misc/SoState.h>
+
+#include <Inventor/elements/SoDevicePixelRatioElement.h>
+
+SO_ELEMENT_SOURCE(SoDevicePixelRatioElement);
+
+void
+SoDevicePixelRatioElement::initClass(void)
+{
+  SO_ELEMENT_INIT_CLASS(SoDevicePixelRatioElement, inherited);
+}
+
+void
+SoDevicePixelRatioElement::init(SoState * state)
+{
+  inherited::init(state);
+  this->data = 1.0f;
+}
+
+void
+SoDevicePixelRatioElement::set(SoState * state, SoNode * node, float dpr)
+{
+  inherited::set(classStackIndex, state, node, dpr);
+}
+
+void
+SoDevicePixelRatioElement::set(SoState * state, float dpr)
+{
+  SoDevicePixelRatioElement::set(state, NULL, dpr);
+}
+
+float
+SoDevicePixelRatioElement::get(SoState * state)
+{
+  return inherited::get(classStackIndex, state);
+}
+
+SoDevicePixelRatioElement::~SoDevicePixelRatioElement(void)
+{
+}

src/elements/SoElement.cpp

@@ -427,6 +427,7 @@ SoElement::initElements(void)
   SoComplexityElement::initClass();
   SoCreaseAngleElement::initClass();
   SoDecimationPercentageElement::initClass();
+  SoDevicePixelRatioElement::initClass();
   SoFocalDistanceElement::initClass();
   SoFontSizeElement::initClass();
   SoLineWidthElement::initClass();

src/elements/all-elements-cpp.cpp

@@ -50,6 +50,7 @@
 #include "SoCullElement.cpp"
 #include "SoDecimationPercentageElement.cpp"
 #include "SoDecimationTypeElement.cpp"
+#include "SoDevicePixelRatioElement.cpp"
 #include "SoDepthBufferElement.cpp"
 #include "SoDiffuseColorElement.cpp"
 #include "SoDrawStyleElement.cpp"

src/misc/SoSceneManager.cpp

@@ -314,6 +314,18 @@ SoSceneManager::getWindowSize(void) const
   return PRIVATE(this)->rendermanager->getWindowSize();
 }
 
+void
+SoSceneManager::setDevicePixelRatio(float dpr)
+{
+  PRIVATE(this)->rendermanager->setDevicePixelRatio(dpr);
+}
+
+float
+SoSceneManager::getDevicePixelRatio(void) const
+{
+  return PRIVATE(this)->rendermanager->getDevicePixelRatio();
+}
+
 /*!
   Set size of rendering area for the viewport within the current
   window.

src/rendering/SoRenderManager.cpp

@@ -58,6 +58,7 @@
 #include <Inventor/elements/SoTextureQualityElement.h>
 #include <Inventor/elements/SoTextureOverrideElement.h>
 #include <Inventor/elements/SoComplexityTypeElement.h>
+#include <Inventor/elements/SoDevicePixelRatioElement.h>
 #include <Inventor/elements/SoLazyElement.h>
 
 #include <algorithm>
@@ -264,6 +265,7 @@ SoRenderManager::SoRenderManager(void)
   PRIVATE(this)->stereostencilmask = NULL;
   PRIVATE(this)->superimpositions = NULL;
   PRIVATE(this)->viewport = SbViewportRegion(SbVec2s(400, 400));
+  PRIVATE(this)->devicePixelRatio = 1.0f;
 
   PRIVATE(this)->doublebuffer = TRUE;
   PRIVATE(this)->deleteaudiorenderaction = TRUE;
@@ -698,7 +700,13 @@ SoRenderManager::render(SoGLRenderAction * action,
     for (int i = 0; i < PRIVATE(this)->superimpositions->getLength(); i++) {
       Superimposition * s = (Superimposition *) (*PRIVATE(this)->superimpositions)[i];
       if (s->getStateFlags() & Superimposition::BACKGROUND) {
+        SoState * state = action->getState();
+        state->push();
+        SoDevicePixelRatioElement::set(state,
+                                       PRIVATE(this)->dummynode,
+                                       PRIVATE(this)->devicePixelRatio);
         s->render(action, clearwindow_tmp);
+        state->pop();
         clearwindow_tmp = FALSE;
       }
     }
@@ -712,7 +720,13 @@ SoRenderManager::render(SoGLRenderAction * action,
     for (int i = 0; i < PRIVATE(this)->superimpositions->getLength(); i++) {
       Superimposition * s = (Superimposition *) (*PRIVATE(this)->superimpositions)[i];
       if (!(s->getStateFlags() & Superimposition::BACKGROUND)) {
+        SoState * state = action->getState();
+        state->push();
+        SoDevicePixelRatioElement::set(state,
+                                       PRIVATE(this)->dummynode,
+                                       PRIVATE(this)->devicePixelRatio);
         s->render(action);
+        state->pop();
       }
     }
   }
@@ -845,6 +859,7 @@ SoRenderManager::renderSingle(SoGLRenderAction * action,
   state->push();
 
   SoNode * node = PRIVATE(this)->dummynode;
+  SoDevicePixelRatioElement::set(state, node, PRIVATE(this)->devicePixelRatio);
 
   if (!this->isTexturesEnabled()) {
     SoTextureQualityElement::set(state, node, 0.0f);
@@ -1266,6 +1281,20 @@ SoRenderManager::getWindowSize(void) const
   return PRIVATE(this)->viewport.getWindowSize();
 }
 
+void
+SoRenderManager::setDevicePixelRatio(float dpr)
+{
+  if (PRIVATE(this)->devicePixelRatio == dpr) return;
+  PRIVATE(this)->devicePixelRatio = dpr;
+  this->scheduleRedraw();
+}
+
+float
+SoRenderManager::getDevicePixelRatio(void) const
+{
+  return PRIVATE(this)->devicePixelRatio;
+}
+
 /*!
   Set size of rendering area for the viewport within the current
   window.

src/rendering/SoRenderManagerP.h

@@ -114,6 +114,7 @@ class SoRenderManagerP {
   SbBool deleteglaction;
 #endif
   SbViewportRegion viewport;
+  float devicePixelRatio;
 
   SoRenderManager::StereoMode stereostenciltype;
   SoRenderManager::RenderMode rendermode;

testsuite/SceneManagerCoreTest.cpp

@@ -2,6 +2,7 @@
 #include <Inventor/SoRenderManager.h>
 #include <Inventor/SoSceneManager.h>
 #include <Inventor/SbViewportRegion.h>
+#include <Inventor/elements/SoDevicePixelRatioElement.h>
 #include <Inventor/nodes/SoOrthographicCamera.h>
 #include <Inventor/nodes/SoSeparator.h>
 
@@ -25,6 +26,10 @@ checkRenderManager(SoRenderManager & manager)
   manager.setWindowSize(SbVec2s(800, 600));
   if (manager.getWindowSize() != SbVec2s(800, 600)) return 1;
 
+  if (manager.getDevicePixelRatio() != 1.0f) return 1;
+  manager.setDevicePixelRatio(2.0f);
+  if (manager.getDevicePixelRatio() != 2.0f) return 1;
+
   manager.setSize(SbVec2s(640, 480));
   if (manager.getSize() != SbVec2s(640, 480)) return 1;
 
@@ -60,6 +65,10 @@ checkSceneManager(SoSceneManager & manager)
   manager.setWindowSize(SbVec2s(800, 600));
   if (manager.getWindowSize() != SbVec2s(800, 600)) return 1;
 
+  if (manager.getDevicePixelRatio() != 1.0f) return 1;
+  manager.setDevicePixelRatio(2.0f);
+  if (manager.getDevicePixelRatio() != 2.0f) return 1;
+
   manager.setSize(SbVec2s(640, 480));
   if (manager.getSize() != SbVec2s(640, 480)) return 1;