Renderer/GLHelpers: handle primitive restart when possible

Change-Id: I9270ec5f7909dce84da64a6b539b14afd572a3cc
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

12 files changed, 71 insertions, 13 deletions

diff --git a/src/render/backend/qgraphicscontext.cpp b/src/render/backend/qgraphicscontext.cpp
index 797f31041..a13b9572a 100644
--- a/src/render/backend/qgraphicscontext.cpp
+++ b/src/render/backend/qgraphicscontext.cpp
@@ -742,6 +742,18 @@ GLint QGraphicsContext::maxClipPlaneCount()
     return m_glHelper->maxClipPlaneCount();
 }
 
+void QGraphicsContext::enablePrimitiveRestart(int restartIndex)
+{
+    if (m_glHelper->supportsFeature(QGraphicsHelperInterface::PrimitiveRestart))
+        m_glHelper->enablePrimitiveRestart(restartIndex);
+}
+
+void QGraphicsContext::disablePrimitiveRestart()
+{
+    if (m_glHelper->supportsFeature(QGraphicsHelperInterface::PrimitiveRestart))
+        m_glHelper->disablePrimitiveRestart();
+}
+
 /*!
     \internal
     Returns a texture unit for a texture, -1 if all texture units are assigned.
diff --git a/src/render/backend/qgraphicscontext_p.h b/src/render/backend/qgraphicscontext_p.h
index 04f498ba6..afffbf4ec 100644
--- a/src/render/backend/qgraphicscontext_p.h
+++ b/src/render/backend/qgraphicscontext_p.h
@@ -181,6 +181,8 @@ public:
     void    enableClipPlane(int clipPlane);
     void    disableClipPlane(int clipPlane);
     GLint   maxClipPlaneCount();
+    void    enablePrimitiveRestart(int restartIndex);
+    void    disablePrimitiveRestart();
 
     // Helper methods
     static GLint elementType(GLint type);
diff --git a/src/render/backend/qgraphicshelperes2.cpp b/src/render/backend/qgraphicshelperes2.cpp
index 4481101b3..4559497c4 100644
--- a/src/render/backend/qgraphicshelperes2.cpp
+++ b/src/render/backend/qgraphicshelperes2.cpp
@@ -302,12 +302,6 @@ void QGraphicsHelperES2::bindFrameBufferAttachment(QOpenGLTexture *texture, cons
 bool QGraphicsHelperES2::supportsFeature(QGraphicsHelperInterface::Feature feature) const
 {
     switch (feature) {
-    case MRT:
-        return false;
-    case Tessellation:
-        return false;
-    case UniformBufferObject:
-        return false;
     default:
         return false;
     }
@@ -528,6 +522,14 @@ GLint QGraphicsHelperES2::maxClipPlaneCount()
     return 0;
 }
 
+void QGraphicsHelperES2::enablePrimitiveRestart(int)
+{
+}
+
+void QGraphicsHelperES2::disablePrimitiveRestart()
+{
+}
+
 } // Render
 } //Qt3D
 
diff --git a/src/render/backend/qgraphicshelperes2_p.h b/src/render/backend/qgraphicshelperes2_p.h
index 3e15ee9bf..57e77e9ec 100644
--- a/src/render/backend/qgraphicshelperes2_p.h
+++ b/src/render/backend/qgraphicshelperes2_p.h
@@ -89,6 +89,8 @@ public:
     void enableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     void disableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     GLint maxClipPlaneCount() Q_DECL_OVERRIDE;
+    void enablePrimitiveRestart(int primitiveRestartIndex) Q_DECL_OVERRIDE;
+    void disablePrimitiveRestart() Q_DECL_OVERRIDE;
 
 private:
     QOpenGLFunctions *m_funcs;
diff --git a/src/render/backend/qgraphicshelpergl2.cpp b/src/render/backend/qgraphicshelpergl2.cpp
index 5a9373860..b3ef699bc 100644
--- a/src/render/backend/qgraphicshelpergl2.cpp
+++ b/src/render/backend/qgraphicshelpergl2.cpp
@@ -303,10 +303,6 @@ bool QGraphicsHelperGL2::supportsFeature(QGraphicsHelperInterface::Feature featu
     switch (feature) {
     case MRT:
         return (m_fboFuncs != Q_NULLPTR);
-    case Tessellation:
-        return false;
-    case UniformBufferObject:
-        return false;
     default:
         return false;
     }
@@ -536,6 +532,14 @@ GLint QGraphicsHelperGL2::maxClipPlaneCount()
     return max;
 }
 
+void QGraphicsHelperGL2::enablePrimitiveRestart(int)
+{
+}
+
+void QGraphicsHelperGL2::disablePrimitiveRestart()
+{
+}
+
 } // Render
 } // Qt3D
 
diff --git a/src/render/backend/qgraphicshelpergl2_p.h b/src/render/backend/qgraphicshelpergl2_p.h
index ae25e201d..673c48125 100644
--- a/src/render/backend/qgraphicshelpergl2_p.h
+++ b/src/render/backend/qgraphicshelpergl2_p.h
@@ -91,6 +91,8 @@ public:
     void enableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     void disableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     GLint maxClipPlaneCount() Q_DECL_OVERRIDE;
+    void enablePrimitiveRestart(int primitiveRestartIndex) Q_DECL_OVERRIDE;
+    void disablePrimitiveRestart() Q_DECL_OVERRIDE;
 
 private:
     QOpenGLFunctions_2_0 *m_funcs;
diff --git a/src/render/backend/qgraphicshelpergl3.cpp b/src/render/backend/qgraphicshelpergl3.cpp
index 8901185a7..f5c046e61 100644
--- a/src/render/backend/qgraphicshelpergl3.cpp
+++ b/src/render/backend/qgraphicshelpergl3.cpp
@@ -324,11 +324,11 @@ bool QGraphicsHelperGL3::supportsFeature(QGraphicsHelperInterface::Feature featu
 {
     switch (feature) {
     case MRT:
+    case UniformBufferObject:
+    case PrimitiveRestart:
         return true;
     case Tessellation:
         return !m_tessFuncs.isNull();
-    case UniformBufferObject:
-        return true;
     default:
         return false;
     }
@@ -881,6 +881,17 @@ GLint QGraphicsHelperGL3::maxClipPlaneCount()
     return max;
 }
 
+void QGraphicsHelperGL3::enablePrimitiveRestart(int primitiveRestartIndex)
+{
+    m_funcs->glPrimitiveRestartIndex(primitiveRestartIndex);
+    m_funcs->glEnable(GL_PRIMITIVE_RESTART);
+}
+
+void QGraphicsHelperGL3::disablePrimitiveRestart()
+{
+    m_funcs->glDisable(GL_PRIMITIVE_RESTART);
+}
+
 } // Render
 } // Qt3D
 
diff --git a/src/render/backend/qgraphicshelpergl3_p.h b/src/render/backend/qgraphicshelpergl3_p.h
index 80917d089..7a3d7a61c 100644
--- a/src/render/backend/qgraphicshelpergl3_p.h
+++ b/src/render/backend/qgraphicshelpergl3_p.h
@@ -92,6 +92,8 @@ public:
     void enableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     void disableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     GLint maxClipPlaneCount() Q_DECL_OVERRIDE;
+    void enablePrimitiveRestart(int primitiveRestartIndex) Q_DECL_OVERRIDE;
+    void disablePrimitiveRestart() Q_DECL_OVERRIDE;
 
 private:
     QOpenGLFunctions_3_2_Core *m_funcs;
diff --git a/src/render/backend/qgraphicshelpergl4.cpp b/src/render/backend/qgraphicshelpergl4.cpp
index 103ea15bf..4102bfa4c 100644
--- a/src/render/backend/qgraphicshelpergl4.cpp
+++ b/src/render/backend/qgraphicshelpergl4.cpp
@@ -863,6 +863,17 @@ GLint QGraphicsHelperGL4::maxClipPlaneCount()
     return max;
 }
 
+void QGraphicsHelperGL4::enablePrimitiveRestart(int primitiveRestartIndex)
+{
+    m_funcs->glPrimitiveRestartIndex(primitiveRestartIndex);
+    m_funcs->glEnable(GL_PRIMITIVE_RESTART);
+}
+
+void QGraphicsHelperGL4::disablePrimitiveRestart()
+{
+    m_funcs->glDisable(GL_PRIMITIVE_RESTART);
+}
+
 } // Render
 } // Qt3D
 
diff --git a/src/render/backend/qgraphicshelpergl4_p.h b/src/render/backend/qgraphicshelpergl4_p.h
index 0c2f82f3c..d74ebfe80 100644
--- a/src/render/backend/qgraphicshelpergl4_p.h
+++ b/src/render/backend/qgraphicshelpergl4_p.h
@@ -91,6 +91,8 @@ public:
     void enableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     void disableClipPlane(int clipPlane) Q_DECL_OVERRIDE;
     GLint maxClipPlaneCount() Q_DECL_OVERRIDE;
+    void enablePrimitiveRestart(int primitiveRestartIndex) Q_DECL_OVERRIDE;
+    void disablePrimitiveRestart() Q_DECL_OVERRIDE;
 
 private:
     QOpenGLFunctions_4_3_Core *m_funcs;
diff --git a/src/render/backend/qgraphicshelperinterface_p.h b/src/render/backend/qgraphicshelperinterface_p.h
index 4ec22e28e..16543382d 100644
--- a/src/render/backend/qgraphicshelperinterface_p.h
+++ b/src/render/backend/qgraphicshelperinterface_p.h
@@ -56,7 +56,8 @@ public:
         MRT = 0,
         Tessellation,
         UniformBufferObject,
-        BindableFragmentOutputs
+        BindableFragmentOutputs,
+        PrimitiveRestart
     };
 
     virtual ~QGraphicsHelperInterface() {}
@@ -96,6 +97,8 @@ public:
     virtual void    enableClipPlane(int clipPlane) = 0;
     virtual void    disableClipPlane(int clipPlane) = 0;
     virtual GLint   maxClipPlaneCount() = 0;
+    virtual void    enablePrimitiveRestart(int primitiveRestartIndex) = 0;
+    virtual void    disablePrimitiveRestart() = 0;
 };
 
 
diff --git a/src/render/backend/renderer.cpp b/src/render/backend/renderer.cpp
index b79ebbecb..5e91da014 100644
--- a/src/render/backend/renderer.cpp
+++ b/src/render/backend/renderer.cpp
@@ -916,6 +916,9 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
             if (rGeometryRenderer->primitiveType() == QGeometryRenderer::Patches)
                 m_graphicsContext->setVerticesPerPatch(rGeometry->verticesPerPatch());
 
+            if (rGeometryRenderer->primitiveRestart())
+                m_graphicsContext->enablePrimitiveRestart(rGeometryRenderer->restartIndex());
+
             // TO DO: Add glMulti Draw variants
             if (!drawInstanced) { // Non instanced Rendering
                 if (drawIndexed)
@@ -945,6 +948,8 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
             if (err)
                 qCWarning(Rendering) << "GL error after drawing mesh:" << QString::number(err, 16);
 
+            if (rGeometryRenderer->primitiveRestart())
+                m_graphicsContext->disablePrimitiveRestart();
 
             // Maybe we could cache the VAO and release it only at the end of the exectute frame
             // in case we are always reusing the same one ?