Refactor the rendernode example

By removing the Renderer abstraction it becomes easier to follow and
understand.

Change-Id: Iddacb461d51a75864983850660c5480985b3524f
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

examples/quick/scenegraph/rendernode/customrenderitem.cpp

@@ -45,51 +45,6 @@
 #include "openglrenderer.h"
 #include "d3d12renderer.h"
 
-CustomRenderNode::~CustomRenderNode()
-{
-    releaseResources();
-}
-
-void CustomRenderNode::render(const RenderState *state)
-{
-    QSGRendererInterface *ri = m_item->window()->rendererInterface();
-    if (!ri)
-        return;
-
-    if (!m_renderer) {
-        switch (ri->graphicsAPI()) {
-        case QSGRendererInterface::OpenGL:
-#ifndef QT_NO_OPENGL
-            m_renderer = new OpenGLRenderer(m_item, this);
-#endif
-            break;
-        case QSGRendererInterface::Direct3D12:
-#ifdef HAS_D3D12
-            m_renderer = new D3D12Renderer(m_item, this);
-#endif
-            break;
-        default:
-            break;
-        }
-        Q_ASSERT(m_renderer);
-        m_renderer->init();
-    }
-
-    m_renderer->render(state);
-}
-
-// No need to reimplement changedStates() since our rendering is so simple,
-// without involving any state changes.
-
-void CustomRenderNode::releaseResources()
-{
-    if (!m_renderer)
-        return;
-
-    delete m_renderer;
-    m_renderer = nullptr;
-}
-
 CustomRenderItem::CustomRenderItem(QQuickItem *parent)
     : QQuickItem(parent)
 {
@@ -99,9 +54,26 @@ CustomRenderItem::CustomRenderItem(QQuickItem *parent)
 
 QSGNode *CustomRenderItem::updatePaintNode(QSGNode *node, UpdatePaintNodeData *)
 {
-    CustomRenderNode *n = static_cast<CustomRenderNode *>(node);
-    if (!node)
-        n = new CustomRenderNode(this);
+    QSGRenderNode *n = static_cast<QSGRenderNode *>(node);
+    if (!n) {
+        QSGRendererInterface *ri = window()->rendererInterface();
+        if (!ri)
+            return nullptr;
+        switch (ri->graphicsAPI()) {
+            case QSGRendererInterface::OpenGL:
+#ifndef QT_NO_OPENGL
+                n = new OpenGLRenderNode(this);
+                break;
+#endif
+            case QSGRendererInterface::Direct3D12:
+#ifdef HAS_D3D12
+                n = new D3D12RenderNode(this);
+                break;
+#endif
+            default:
+                return nullptr;
+        }
+    }
 
     return n;
 }

examples/quick/scenegraph/rendernode/customrenderitem.h

@@ -42,29 +42,6 @@
 #define CUSTOMRENDERITEM_H
 
 #include <QQuickItem>
-#include <QSGRenderNode>
-
-class CustomRenderer
-{
-public:
-    virtual ~CustomRenderer() { }
-    virtual void init() = 0;
-    virtual void render(const QSGRenderNode::RenderState *state) = 0;
-};
-
-class CustomRenderNode : public QSGRenderNode
-{
-public:
-    CustomRenderNode(QQuickItem *item) : m_item(item) { }
-    ~CustomRenderNode();
-
-    void render(const RenderState *state) override;
-    void releaseResources() override;
-
-private:
-    QQuickItem *m_item;
-    CustomRenderer *m_renderer = nullptr;
-};
 
 class CustomRenderItem : public QQuickItem
 {

examples/quick/scenegraph/rendernode/d3d12renderer.cpp

@@ -39,6 +39,7 @@
 ****************************************************************************/
 
 #include "d3d12renderer.h"
+#include <QQuickItem>
 #include <QQuickWindow>
 #include <QSGRendererInterface>
 
@@ -47,15 +48,34 @@
 #include "vs_shader.hlslh"
 #include "ps_shader.hlslh"
 
-D3D12Renderer::D3D12Renderer(QQuickItem *item, QSGRenderNode *node)
-    : m_item(item),
-      m_node(node),
-      vbPtr(nullptr),
-      cbPtr(nullptr)
+D3D12RenderNode::D3D12RenderNode(QQuickItem *item)
+    : m_item(item)
 {
 }
 
-void D3D12Renderer::init()
+D3D12RenderNode::~D3D12RenderNode()
+{
+    releaseResources();
+}
+
+void D3D12RenderNode::releaseResources()
+{
+    if (vbPtr) {
+        vertexBuffer->Unmap(0, nullptr);
+        vbPtr = nullptr;
+    }
+    if (cbPtr) {
+        constantBuffer->Unmap(0, nullptr);
+        cbPtr = nullptr;
+    }
+    constantBuffer = nullptr;
+    vertexBuffer = nullptr;
+    rootSignature = nullptr;
+    pipelineState = nullptr;
+    m_device = nullptr;
+}
+
+void D3D12RenderNode::init()
 {
     QSGRendererInterface *rif = m_item->window()->rendererInterface();
     m_device = static_cast<ID3D12Device *>(rif->getResource(QSGRendererInterface::Device));
@@ -180,22 +200,17 @@ void D3D12Renderer::init()
     }
 }
 
-D3D12Renderer::~D3D12Renderer()
+void D3D12RenderNode::render(const RenderState *state)
 {
-    if (vbPtr)
-        vertexBuffer->Unmap(0, nullptr);
-    if (cbPtr)
-        constantBuffer->Unmap(0, nullptr);
-}
+    if (!m_device)
+        init();
 
-void D3D12Renderer::render(const QSGRenderNode::RenderState *state)
-{
     QSGRendererInterface *rif = m_item->window()->rendererInterface();
     ID3D12GraphicsCommandList *commandList = static_cast<ID3D12GraphicsCommandList *>(rif->getResource(QSGRendererInterface::CommandList));
     Q_ASSERT(commandList);
 
     const int msize = 16 * sizeof(float);
-    memcpy(cbPtr, m_node->matrix()->constData(), msize);
+    memcpy(cbPtr, matrix()->constData(), msize);
     memcpy(cbPtr + msize, state->projectionMatrix()->constData(), msize);
 
     const QPointF p0(m_item->width() - 1, m_item->height() - 1);

examples/quick/scenegraph/rendernode/d3d12renderer.h

@@ -41,35 +41,38 @@
 #ifndef D3D12RENDERER_H
 #define D3D12RENDERER_H
 
-#include "customrenderitem.h"
 #include <qsgrendernode.h>
 
 #ifdef HAS_D3D12
 
+class QQuickItem;
+
 #include <d3d12.h>
 #include <wrl/client.h>
 
 using namespace Microsoft::WRL;
 
-class D3D12Renderer : public CustomRenderer
+class D3D12RenderNode : public QSGRenderNode
 {
 public:
-    D3D12Renderer(QQuickItem *item, QSGRenderNode *node);
-    ~D3D12Renderer();
-    void init() override;
-    void render(const QSGRenderNode::RenderState *state) override;
+    D3D12RenderNode(QQuickItem *item);
+    ~D3D12RenderNode();
+
+    void render(const RenderState *state) override;
+    void releaseResources() override;
 
 private:
+    void init();
+
     QQuickItem *m_item;
-    QSGRenderNode *m_node;
-    ID3D12Device *m_device;
+    ID3D12Device *m_device = nullptr;
     ComPtr<ID3D12PipelineState> pipelineState;
     ComPtr<ID3D12RootSignature> rootSignature;
     ComPtr<ID3D12Resource> vertexBuffer;
     ComPtr<ID3D12Resource> constantBuffer;
     D3D12_VERTEX_BUFFER_VIEW vertexBufferView;
-    quint8 *vbPtr;
-    quint8 *cbPtr;
+    quint8 *vbPtr = nullptr;
+    quint8 *cbPtr = nullptr;
 };
 
 #endif // HAS_D3D12

examples/quick/scenegraph/rendernode/openglrenderer.cpp

@@ -39,6 +39,7 @@
 ****************************************************************************/
 
 #include "openglrenderer.h"
+#include <QQuickItem>
 
 #ifndef QT_NO_OPENGL
 
@@ -46,13 +47,28 @@
 #include <QOpenGLBuffer>
 #include <QOpenGLFunctions>
 
-OpenGLRenderer::OpenGLRenderer(QQuickItem *item, QSGRenderNode *node)
-    : m_item(item),
-      m_node(node)
+OpenGLRenderNode::OpenGLRenderNode(QQuickItem *item)
+    : m_item(item)
 {
 }
 
-void OpenGLRenderer::init()
+OpenGLRenderNode::~OpenGLRenderNode()
+{
+    releaseResources();
+}
+
+// No need to reimplement changedStates() since our rendering is so simple,
+// without involving any state changes.
+
+void OpenGLRenderNode::releaseResources()
+{
+    delete m_program;
+    m_program = nullptr;
+    delete m_vbo;
+    m_vbo = nullptr;
+}
+
+void OpenGLRenderNode::init()
 {
     m_program = new QOpenGLShaderProgram;
 
@@ -98,18 +114,15 @@ void OpenGLRenderer::init()
     m_vbo->release();
 }
 
-OpenGLRenderer::~OpenGLRenderer()
+void OpenGLRenderNode::render(const RenderState *state)
 {
-    delete m_program;
-    delete m_vbo;
-}
+    if (!m_program)
+        init();
 
-void OpenGLRenderer::render(const QSGRenderNode::RenderState *state)
-{
     QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
 
     m_program->bind();
-    m_program->setUniformValue(m_matrixUniform, *state->projectionMatrix() * *m_node->matrix());
+    m_program->setUniformValue(m_matrixUniform, *state->projectionMatrix() * *matrix());
 
     m_vbo->bind();
 

examples/quick/scenegraph/rendernode/openglrenderer.h

@@ -41,25 +41,27 @@
 #ifndef OPENGLRENDERER_H
 #define OPENGLRENDERER_H
 
-#include "customrenderitem.h"
 #include <qsgrendernode.h>
 
 #ifndef QT_NO_OPENGL
 
+class QQuickItem;
 class QOpenGLShaderProgram;
 class QOpenGLBuffer;
 
-class OpenGLRenderer : public CustomRenderer
+class OpenGLRenderNode : public QSGRenderNode
 {
 public:
-    OpenGLRenderer(QQuickItem *item, QSGRenderNode *node);
-    ~OpenGLRenderer();
-    void init() override;
-    void render(const QSGRenderNode::RenderState *state) override;
+    OpenGLRenderNode(QQuickItem *item);
+    ~OpenGLRenderNode();
+
+    void render(const RenderState *state) override;
+    void releaseResources() override;
 
 private:
+    void init();
+
     QQuickItem *m_item;
-    QSGRenderNode *m_node;
     QOpenGLShaderProgram *m_program = nullptr;
     int m_matrixUniform;
     QOpenGLBuffer *m_vbo = nullptr;