Add support to move the camera so that the entire model is visible

Adds QCamera::viewAll(), QCamera::viewEntity() and QCamera::viewSphere()
to move and rotate the camera so that the view center is the center
of the sphere and the sphere fits inside the viewport

Only works in perspective projection.

Introduces a job to compute the bounding sphere of the scene
excluding the camera.

Change-Id: Id9d67787ea91c354009d5358d5db63a1c9480c70
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/src/render/frontend/qcameralens.cpp b/src/render/frontend/qcameralens.cpp
index 3c6b8db68..c9be49484 100644
--- a/src/render/frontend/qcameralens.cpp
+++ b/src/render/frontend/qcameralens.cpp
@@ -224,6 +224,43 @@ QCameraLensPrivate::QCameraLensPrivate()
 {
 }
 
+void QCameraLens::viewAll(Qt3DCore::QNodeId cameraId)
+{
+    Q_D(QCameraLens);
+    if (d->m_projectionType == PerspectiveProjection) {
+        QVariant v;
+        v.setValue(cameraId);
+        d->m_pendingViewAllCommand = sendCommand(QLatin1Literal("QueryRootBoundingVolume"), v);
+    }
+}
+
+void QCameraLens::viewEntity(Qt3DCore::QNodeId entityId, Qt3DCore::QNodeId cameraId)
+{
+    Q_D(QCameraLens);
+    if (d->m_projectionType == PerspectiveProjection) {
+        QVector<Qt3DCore::QNodeId> ids = {entityId, cameraId};
+        QVariant v;
+        v.setValue(ids);
+        d->m_pendingViewAllCommand = sendCommand(QLatin1Literal("QueryEntityBoundingVolume"), v);
+    }
+}
+
+void QCameraLensPrivate::processViewAllCommand(Qt3DCore::QNodeCommand::CommandId commandId,
+                                               const QVariant &data)
+{
+    Q_Q(QCameraLens);
+    if (m_pendingViewAllCommand != commandId)
+        return;
+
+    QVector<float> boundingVolumeData = data.value< QVector<float> >();
+    if (boundingVolumeData.size() != 4)
+        return;
+    QVector3D center(boundingVolumeData[0], boundingVolumeData[1], boundingVolumeData[2]);
+    float radius = boundingVolumeData[3];
+    Q_EMIT q->viewSphere(center, radius);
+    m_pendingViewAllCommand = Qt3DCore::QNodeCommand::CommandId();
+}
+
 /*!
  * Constructs a QCameraLens with given \a parent
  */
@@ -593,6 +630,22 @@ Qt3DCore::QNodeCreatedChangeBasePtr QCameraLens::createNodeCreationChange() cons
     return creationChange;
 }
 
+void QCameraLens::sceneChangeEvent(const Qt3DCore::QSceneChangePtr &change)
+{
+    Q_D(QCameraLens);
+    switch (change->type()) {
+    case Qt3DCore::CommandRequested: {
+        Qt3DCore::QNodeCommandPtr command = qSharedPointerCast<Qt3DCore::QNodeCommand>(change);
+
+        if (command->name() == QLatin1Literal("ViewAll"))
+            d->processViewAllCommand(command->inReplyTo(), command->data());
+    }
+        break;
+    default:
+        break;
+    }
+}
+
 } // Qt3DRender
 
 QT_END_NAMESPACE