Merge pull request #6576 from lrineau/QGLViewer-fix_picking_with_HiDPI_screen-GF

Fix 3D demo with HiDPI screen

Author: sloriot

GraphicsView/include/CGAL/Qt/camera.h

@@ -18,6 +18,7 @@
 #include <CGAL/Qt/quaternion.h>
 #include <CGAL/export/Qt.h>
 #include <QOpenGLFunctions_2_1>
+#include <QOpenGLFunctions>
 
 namespace CGAL{
 class QGLViewer;
@@ -199,6 +200,7 @@ public Q_SLOTS:
   CGAL::QGLViewer's window dimensions when the Camera is attached to a CGAL::QGLViewer. See
   also QOpenGLWidget::height() */
   int screenHeight() const { return screenHeight_; }
+  qreal devicePixelRatio() const { return devicePixelRatio_; }
   void getViewport(GLint viewport[4]) const;
   qreal pixelGLRatio(const Vec &position) const;
 
@@ -279,7 +281,7 @@ public Q_SLOTS:
     setScreenWidthAndHeight(int(100.0 * aspect), 100);
   }
 
-  void setScreenWidthAndHeight(int width, int height);
+  void setScreenWidthAndHeight(int width, int height, qreal devicePixelRatio = 1.0);
   /*! Sets the zNearCoefficient() value. */
   void setZNearCoefficient(qreal coef) {
     zNearCoef_ = coef;
@@ -444,6 +446,7 @@ private Q_SLOTS:
 
   // C a m e r a   p a r a m e t e r s
   int screenWidth_, screenHeight_; // size of the window, in pixels
+  qreal devicePixelRatio_;
   qreal fieldOfView_;              // in radians
   Vec sceneCenter_;
   qreal sceneRadius_; // OpenGL units
@@ -467,6 +470,36 @@ private Q_SLOTS:
   KeyFrameInterpolator *interpolationKfi_;
 };
 
+inline void read_pixel(const QPoint &pixel, QOpenGLFunctions *p,
+                        const Camera *camera, GLenum format, GLenum type,
+                        GLvoid *pixel_data) {
+  const auto pixel_ratio = camera->devicePixelRatio();
+  p->glReadPixels(pixel.x() * pixel_ratio,
+                  (camera->screenHeight() - pixel.y()) * pixel_ratio - 1, 1, 1,
+                  format, type, pixel_data);
+}
+
+inline auto read_pixel_as_float_rgb(const QPoint &pixel, QOpenGLFunctions *p,
+                                    const Camera *camera) {
+  std::array<float, 3> res;
+  read_pixel(pixel, p, camera, GL_RGB, GL_FLOAT, res.data());
+  return res;
+}
+
+inline auto read_pixel_as_ubyte_rgba(const QPoint &pixel, QOpenGLFunctions *p,
+                                    const Camera *camera) {
+  std::array<GLubyte, 4> res;
+  read_pixel(pixel, p, camera, GL_RGBA, GL_UNSIGNED_BYTE, res.data());
+  return res;
+}
+
+inline float read_depth_under_pixel(const QPoint &pixel, QOpenGLFunctions *p,
+                                    const Camera *camera) {
+  float depth = 2.0f;
+  read_pixel(pixel, p, camera, GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
+  return depth;
+}
+
 } // namespace qglviewer
 } //CGAL
 #endif // QGLVIEWER_CAMERA_H

GraphicsView/include/CGAL/Qt/camera_impl.h

@@ -160,10 +160,11 @@ frustrum coherence.
 If your Camera is used without a CGAL::QGLViewer (offscreen rendering, shadow maps),
 use setAspectRatio() instead to define the projection matrix. */
 CGAL_INLINE_FUNCTION
-void Camera::setScreenWidthAndHeight(int width, int height) {
+void Camera::setScreenWidthAndHeight(int width, int height, qreal devicePixelRatio) {
   // Prevent negative and zero dimensions that would cause divisions by zero.
   screenWidth_ = width > 0 ? width : 1;
   screenHeight_ = height > 0 ? height : 1;
+  devicePixelRatio_ = devicePixelRatio;
   projectionMatrixIsUpToDate_ = false;
 }
 
@@ -884,8 +885,7 @@ Vec Camera::pointUnderPixel(const QPoint &pixel, bool &found) const {
   // Qt uses upper corner for its origin while GL uses the lower corner.
   if(auto p = dynamic_cast<QOpenGLFunctions*>(parent()))
   {
-    p->glReadPixels(pixel.x(), screenHeight() - 1 - pixel.y(), 1, 1,
-                    GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
+    depth = read_depth_under_pixel(pixel, p, this);
   }
   found = depth < 1.0;
   Vec point(pixel.x(), pixel.y(), depth);

GraphicsView/include/CGAL/Qt/qglviewer_impl.h

@@ -807,7 +807,7 @@ void CGAL::QGLViewer::setCamera(qglviewer::Camera *const camera) {
 
   camera->setSceneRadius(sceneRadius());
   camera->setSceneCenter(sceneCenter());
-  camera->setScreenWidthAndHeight(width(), height());
+  camera->setScreenWidthAndHeight(width(), height(), devicePixelRatio());
 
   // Disconnect current camera from this viewer.
   disconnect(this->camera()->frame(), SIGNAL(manipulated()), this,
@@ -1147,7 +1147,9 @@ void CGAL::QGLViewer::beginSelection(const QPoint &point)
 {
   makeCurrent();
   glEnable(GL_SCISSOR_TEST);
-  glScissor(point.x(), camera()->screenHeight()-1-point.y(), 1, 1);
+  glScissor(point.x() * devicePixelRatio(),
+            (camera()->screenHeight() - point.y()) * devicePixelRatio() - 1, 1,
+            1);
 }
 
 /*! This method is called by select() after scene elements were drawn by
@@ -2369,7 +2371,7 @@ CGAL_INLINE_FUNCTION
 void CGAL::QGLViewer::resizeGL(int width, int height) {
   QOpenGLWidget::resizeGL(width, height);
   glViewport(0, 0, GLint(width), GLint(height));
-  camera()->setScreenWidthAndHeight(this->width(), this->height());
+  camera()->setScreenWidthAndHeight(this->width(), this->height(), this->devicePixelRatio());
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -3187,10 +3189,11 @@ void CGAL::QGLViewer::drawVisualHints() {
     mvpMatrix.ortho(-1,1,-1,1,-1,1);
     size=30*devicePixelRatio();
     rendering_program.setUniformValue("mvp_matrix", mvpMatrix);
-    glViewport(GLint((camera()->projectedCoordinatesOf(camera()->pivotPoint()).x-size/2)*devicePixelRatio()),
-               GLint((height() - camera()->projectedCoordinatesOf(camera()->pivotPoint()).y-size/2)*devicePixelRatio()), size, size);
-    glScissor (GLint((camera()->projectedCoordinatesOf(camera()->pivotPoint()).x-size/2)*devicePixelRatio()),
-               GLint((height() - camera()->projectedCoordinatesOf(camera()->pivotPoint()).y-size/2)*devicePixelRatio()), size, size);
+    const auto point_2d = camera()->projectedCoordinatesOf(camera()->pivotPoint());
+    glViewport(GLint(point_2d.x*devicePixelRatio()-size/2),
+               GLint((height() - point_2d.y)*devicePixelRatio()-size/2), size, size);
+    glScissor (GLint(point_2d.x*devicePixelRatio()-size/2),
+               GLint((height() - point_2d.y)*devicePixelRatio()-size/2), size, size);
     rendering_program.setUniformValue("color", QColor(::Qt::black));
     glDisable(GL_DEPTH_TEST);
     glDrawArrays(GL_LINES, 0, static_cast<GLsizei>(4));

Polyhedron/demo/Polyhedron/Plugins/Mesh_3/Io_image_plugin.cpp

@@ -116,11 +116,7 @@ public Q_SLOTS:
   boost::optional<DoubleConverter> fc;
   Viewer_interface* viewer;
   void getPixel(const QPoint& e) {
-    float data[3];
-    int vp[4];
-    viewer->glGetIntegerv(GL_VIEWPORT, vp);
-    viewer->glReadPixels(e.x(), vp[3] - e.y(), 1, 1, GL_RGB, GL_FLOAT, data);
-
+    const auto data = read_pixel_as_float_rgb(e, viewer, viewer->camera());
     if(fc) {
       Q_EMIT x(QString::number((*fc)(data[0]), 'f', 6 ));
     } else if(ic) {

Polyhedron/demo/Polyhedron/Plugins/PCA/Scene_edit_box_item.cpp

@@ -1049,11 +1049,7 @@ void Scene_edit_box_item_priv::picking(int& type, int& id, Viewer_interface *vie
   viewer->setBackgroundColor(::Qt::white);
   draw_picking(viewer);
 
-  int rowLength = deviceWidth * 4; // data asked in RGBA,so 4 bytes.
-  const static int dataLength = rowLength * deviceHeight;
-  GLubyte* buffer = new GLubyte[dataLength];
-  // Qt uses upper corner for its origin while GL uses the lower corner.
-  viewer->glReadPixels(picked_pixel.x(), deviceHeight-1-picked_pixel.y(), 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
+  const auto buffer = read_pixel_as_ubyte_rgba(picked_pixel, viewer, viewer->camera());
   //decode ID and pick (don't forget the case nothing is picked
   if(!(buffer[0]==buffer[1] && buffer[1]==buffer[2]))
   {
@@ -1080,7 +1076,6 @@ void Scene_edit_box_item_priv::picking(int& type, int& id, Viewer_interface *vie
       }
     }
   }
-  delete[] buffer;
   viewer->setBackgroundColor(bgColor);
   fbo->release();
   delete fbo;

Polyhedron/demo/Polyhedron/Scene.cpp

@@ -563,9 +563,8 @@ void Scene::renderScene(const QList<Scene_interface::Item_id> &items,
         if(with_names) {
 
           //    read depth buffer at pick location;
-          float depth = 1.0;
-          viewer->glReadPixels(picked_pixel.x(),viewer->camera()->screenHeight()-1-picked_pixel.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
-          if (depth != 1.0)
+          float depth = read_depth_under_pixel(picked_pixel, viewer, viewer->camera());
+          if (depth < 2.0)
           {
             //add object to list of picked objects;
             picked_item_IDs[depth] = index;
@@ -634,7 +633,7 @@ void Scene::renderWireScene(const QList<Scene_interface::Item_id> &items,
 
          //    read depth buffer at pick location;
          float depth = 1.0;
-         viewer->glReadPixels(picked_pixel.x(),viewer->camera()->screenHeight()-1-picked_pixel.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
+         depth = read_depth_under_pixel(picked_pixel, viewer, viewer->camera());
          if (depth != 1.0)
          {
            //add object to list of picked objects;
@@ -676,7 +675,7 @@ void Scene::renderPointScene(const QList<Scene_interface::Item_id> &items,
       if(item.renderingMode() == Points && with_names) {
         //    read depth buffer at pick location;
         float depth = 1.0;
-        viewer->glReadPixels(picked_pixel.x(),viewer->camera()->screenHeight()-1-picked_pixel.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
+        depth = read_depth_under_pixel(picked_pixel, viewer, viewer->camera());
         if (depth != 1.0)
         {
           //add object to list of picked objects;

Polyhedron/demo/Polyhedron/Scene_group_item.cpp

@@ -211,7 +211,7 @@ void Scene_group_item::renderChildren(Viewer_interface *viewer,
     if(with_names) {
       //    read depth buffer at pick location;
       float depth = 1.0;
-      viewer->glReadPixels(picked_pixel.x(),viewer->camera()->screenHeight()-1-picked_pixel.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
+      depth = read_depth_under_pixel(picked_pixel, viewer, viewer->camera());
       if (depth != 1.0)
       {
         //add object to list of picked objects;

Polyhedron/demo/Polyhedron/Scene_spheres_item.cpp

@@ -187,8 +187,6 @@ void Scene_spheres_item::draw(Viewer_interface *viewer) const
     setBuffersFilled(true);
     setBuffersInit(viewer, true);
   }
-  int deviceWidth = viewer->camera()->screenWidth();
-  int deviceHeight = viewer->camera()->screenHeight();
     if(d->has_plane)
     {
       QVector4D cp = cgal_plane_to_vector4d(d->plane);
@@ -207,12 +205,8 @@ void Scene_spheres_item::draw(Viewer_interface *viewer) const
     }
     if(d->pickable && (d->spheres.size() > 1 && viewer->inDrawWithNames()))
     {
-      int rowLength = deviceWidth * 4; // data asked in RGBA,so 4 bytes.
-      const static int dataLength = rowLength * deviceHeight;
-      GLubyte* buffer = new GLubyte[dataLength];
-      // Qt uses upper corner for its origin while GL uses the lower corner.
       QPoint picking_target = viewer->mapFromGlobal(QCursor::pos());
-      viewer->glReadPixels(picking_target.x(), deviceHeight-1-picking_target.y(), 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
+      const auto buffer = read_pixel_as_ubyte_rgba(picking_target, viewer, viewer->camera());
       int ID = (buffer[0] + buffer[1] * 256 +buffer[2] * 256*256) ;
       if(buffer[0]*buffer[1]*buffer[2] < 255*255*255)
       {

Triangulation_3/demo/Triangulation_3/Viewer.cpp

@@ -1696,9 +1696,9 @@ void Viewer::drawWithNames()
     rendering_program.release();
 
     //read depth and store in map
-    GLfloat depth = 1.0f;
-    glReadPixels(picking_pos.x(),camera()->screenHeight()-1-picking_pos.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
-    if (depth != 1.0)
+    GLfloat depth = 2.0f;
+    depth = read_depth_under_pixel(picking_pos, this, this->camera());
+    if (depth < 2.0f)
     {
       picked_IDs[depth] = i;
     }
@@ -1740,9 +1740,9 @@ void Viewer::drawWithNames()
         rendering_program.release();
 
         //read depth and store in map
-        GLfloat depth = 1.0f;
-        glReadPixels(picking_pos.x(),camera()->screenHeight()-1-picking_pos.y(),1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
-        if (depth != 1.0)
+        GLfloat depth = 2.0f;
+        depth = read_depth_under_pixel(picking_pos, this, this->camera());
+        if (depth < 2.0f)
         {
           picked_IDs[depth] = -1;
         }