RenderView: frustum culling

Change-Id: Iacfcfce5d4a339acd29bcaacffb38ce339220ad2
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>

2 files changed, 38 insertions, 13 deletions

diff --git a/src/render/backend/renderview.cpp b/src/render/backend/renderview.cpp
index 88e9ecc2f..62233b267 100644
--- a/src/render/backend/renderview.cpp
+++ b/src/render/backend/renderview.cpp
@@ -91,7 +91,16 @@ bool isEntityInLayers(const Entity *entity, const QStringList &layers)
                 if (layers.contains(layerName))
                     return true;
     }
+    return false;
+}
 
+bool isEntityFrustumCulled(const Entity *entity, const Plane *planes)
+{
+    const Sphere *s = entity->worldBoundingVolumeWithChildren();
+    for (int i = 0; i < 6; ++i) {
+        if (QVector3D::dotProduct(s->center(), planes[i].normal) + planes[i].d < -s->radius())
+            return true;
+    }
     return false;
 }
 
@@ -168,10 +177,7 @@ QUniformValue *RenderView::modelViewMatrix(const QMatrix4x4 &model) const
 
 QUniformValue *RenderView::modelViewProjectionMatrix(const QMatrix4x4 &model) const
 {
-    QMatrix4x4 projection;
-    if (m_data->m_renderCamera)
-        projection = m_data->m_renderCamera->projection();
-    return QUniformValue::fromVariant(projection * *m_data->m_viewMatrix * model, m_allocator);
+    return QUniformValue::fromVariant(*m_data->m_viewProjectionMatrix * model, m_allocator);
 }
 
 QUniformValue *RenderView::inverseModelMatrix(const QMatrix4x4 &model) const
@@ -199,10 +205,7 @@ QUniformValue *RenderView::inverseModelViewMatrix(const QMatrix4x4 &model) const
 
 QUniformValue *RenderView::inverseModelViewProjectionMatrix(const QMatrix4x4 &model) const
 {
-    QMatrix4x4 projection;
-    if (m_data->m_renderCamera)
-        projection = m_data->m_renderCamera->projection();
-    return QUniformValue::fromVariant((projection * *m_data->m_viewMatrix * model).inverted(0), m_allocator);
+    return QUniformValue::fromVariant((*m_data->m_viewProjectionMatrix * model).inverted(0), m_allocator);
 }
 
 QUniformValue *RenderView::modelNormalMatrix(const QMatrix4x4 &model) const
@@ -285,8 +288,9 @@ RenderView::~RenderView()
         m_allocator->deallocate<RenderCommand>(command);
     }
 
-    // Deallocate viewMatrix
+    // Deallocate viewMatrix/viewProjectionMatrix
     m_allocator->deallocate<QMatrix4x4>(m_data->m_viewMatrix);
+    m_allocator->deallocate<QMatrix4x4>(m_data->m_viewProjectionMatrix);
     // Deallocate viewport rect
     m_allocator->deallocate<QRectF>(m_viewport);
     // Deallocate clearColor
@@ -374,12 +378,15 @@ void RenderView::setRenderer(Renderer *renderer)
 }
 
 // Tries to order renderCommand by shader so as to minimize shader changes
-void RenderView::buildRenderCommands(Entity *node)
+void RenderView::buildRenderCommands(Entity *node, const Plane *planes)
 {
     // Skip branches that are not enabled
     if (!node->isEnabled())
         return;
 
+    if (isEntityFrustumCulled(node, planes))
+        return;
+
     // Build renderCommand for current node
     if (isEntityInLayers(node, m_data->m_layers)) {
         GeometryRenderer *geometryRenderer = Q_NULLPTR;
@@ -469,7 +476,7 @@ void RenderView::buildRenderCommands(Entity *node)
 
     // Traverse children
     Q_FOREACH (Entity *child, node->children())
-        buildRenderCommands(child);
+        buildRenderCommands(child, planes);
 }
 
 const AttachmentPack &RenderView::attachmentPack() const
diff --git a/src/render/backend/renderview_p.h b/src/render/backend/renderview_p.h
index e585cb7ff..650d634bc 100644
--- a/src/render/backend/renderview_p.h
+++ b/src/render/backend/renderview_p.h
@@ -86,6 +86,19 @@ class RenderPass;
 typedef QPair<ShaderUniform, QVariant> ActivePropertyContent;
 typedef QPair<QString, ActivePropertyContent > ActiveProperty;
 
+struct Q_AUTOTEST_EXPORT Plane
+{
+    explicit Plane(const QVector4D &planeEquation)
+        : planeEquation(planeEquation)
+        , normal(planeEquation.toVector3D().normalized())
+        , d(planeEquation.w() / planeEquation.toVector3D().length())
+    {}
+
+    const QVector4D planeEquation;
+    const QVector3D normal;
+    const float d;
+};
+
 // This class is kind of analogous to RenderBin but I want to avoid trampling
 // on that until we get this working
 
@@ -117,15 +130,19 @@ public:
         // level of memory management would be better in Entity's matrices as they will
         // help cache performance during iteration
         m_data->m_viewMatrix = m_allocator->allocate<QMatrix4x4>();
+        m_data->m_viewProjectionMatrix = m_allocator->allocate<QMatrix4x4>();
     }
     inline Qt3DCore::QFrameAllocator *allocator() const { return m_allocator; }
 
     inline void setRenderCamera(CameraLens *renderCamera) { m_data->m_renderCamera = renderCamera; }
     inline CameraLens *renderCamera() const { return m_data->m_renderCamera; }
 
-    inline void setViewMatrix(const QMatrix4x4 viewMatrix) { *(m_data->m_viewMatrix) = viewMatrix; }
+    inline void setViewMatrix(const QMatrix4x4 &viewMatrix) { *(m_data->m_viewMatrix) = viewMatrix; }
     inline QMatrix4x4 viewmatrix() const { Q_ASSERT(m_data->m_viewMatrix); return *(m_data->m_viewMatrix); }
 
+    inline void setViewProjectionMatrix(const QMatrix4x4 &viewProjectionMatrix) { *(m_data->m_viewProjectionMatrix) = viewProjectionMatrix; }
+    inline QMatrix4x4 viewProjectionMatrix() const { return *(m_data->m_viewProjectionMatrix); }
+
     inline void setEyePosition(const QVector3D &eyePos) { m_data->m_eyePos = eyePos; }
     inline QVector3D eyePosition() const { return m_data->m_eyePos; }
 
@@ -188,7 +205,7 @@ public:
     inline void setClearBuffer(QClearBuffer::BufferType clearBuffer) { m_clearBuffer = clearBuffer; }
     inline QClearBuffer::BufferType clearBuffer() const { return m_clearBuffer; }
 
-    void buildRenderCommands(Entity *preprocessedTreeRoot);
+    void buildRenderCommands(Entity *preprocessedTreeRoot, const Plane *planes);
     QVector<RenderCommand *> commands() const { return m_commands; }
 
     void addRenderAttachment(Attachment attachment) { m_attachmentPack.addAttachment(attachment); }
@@ -215,6 +232,7 @@ public:
         const TechniqueFilter *m_techniqueFilter;
         const RenderPassFilter *m_passFilter;
         QMatrix4x4 *m_viewMatrix;
+        QMatrix4x4 *m_viewProjectionMatrix;
         QStringList m_layers;
         QList<Qt3DCore::QNodeId> m_sortingCriteria;
         QVector3D m_eyePos;