Adaptable shader effect enablers

The D3D12 node implementation is mostly missing. The rest of the enablers
should be in place now however.

Importing QtQuick 2.8 provides new properties for ShaderEffect:

- shaderType can be used to decide which language should be used

- shaderCompilationType tells if compilation is runtime or offline

- shaderSourceType tells if the vertex/fragmentShader properties refer
  to source strings or source files or pre-compiled bytecode files

The last two are bitmasks. In practice however we will support only
one approach per backend for now (runtime + source string for OpenGL,
offline + bytecode for D3D12).

In addition to QSGShaderEffectNode, introduce the QSGGuiThreadShaderEffectManager
interface. This provides the gui thread bits for the above and performs shader
reflection. Backends that use the new ShaderEffect system must provide both.
For each ShaderEffect item there will be a manager (on the gui thread) and
a node (on the render thread).

Reflection is expected to be done via standard helper libs (d3d12shader
+ D3DReflect from d3dcompiler for the D3D12 backend), or via manually inspecting
SPIR-V, or parsing the source (like the GL path does now), or by using some
3rd party library (not recommended). In any case we require that reflection is
doable on the gui thread without dependencies to the actual graphics API.

The ShaderEffect documentation is greatly extended, covering HLSL and the new
properties.

The test app uses manually compiled shaders on its HLSL path for now. This
is because there is no story yet for build system integration for public
use (the internal HLSL -> bytecode in C header rule is only suitable for
the d3d12 plugin itself, apps need something different).

Change-Id: Id112104906fbcb26b9902a35f19d8d509b340d1b
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

7 files changed, 203 insertions, 3 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwareadaptation.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwareadaptation.cpp
index 05628ea69c..0e2f4f5382 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwareadaptation.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwareadaptation.cpp
@@ -65,7 +65,10 @@ QSGContext *QSGSoftwareAdaptation::create(const QString &) const
 
 QSGContextFactoryInterface::Flags QSGSoftwareAdaptation::flags(const QString &) const
 {
-    return QSGContextFactoryInterface::SupportsShaderEffectV2;
+    // Claim we support adaptable shader effects, then return null for the
+    // shader effect node. The result is shader effects not being rendered,
+    // with the application working fine in all other respects.
+    return QSGContextFactoryInterface::SupportsShaderEffectNode;
 }
 
 QSGRenderLoop *QSGSoftwareAdaptation::createWindowManager()
diff --git a/src/quick/scenegraph/coreapi/qsgrendererinterface.cpp b/src/quick/scenegraph/coreapi/qsgrendererinterface.cpp
index 6a01fac212..b680dbe3d5 100644
--- a/src/quick/scenegraph/coreapi/qsgrendererinterface.cpp
+++ b/src/quick/scenegraph/coreapi/qsgrendererinterface.cpp
@@ -87,6 +87,11 @@ QSGRendererInterface::~QSGRendererInterface()
     \fn QSGRenderNode::GraphicsAPI QSGRenderNode::graphicsAPI() const
 
     Returns the graphics API that is in use by the Qt Quick scenegraph.
+
+    \note This function can be called on any thread. However, the renderer
+    interface's lifetime may be tied to the render thread and therefore calling
+    this function from other threads during the process of application shutdown
+    or QQuickWindow closing is likely to become invalid.
  */
 
 /*!
@@ -98,6 +103,8 @@ QSGRendererInterface::~QSGRendererInterface()
     pointer to an opaque handle that needs to be dereferenced first (for
     example, \c{VkDevice dev = *static_cast<VkDevice *>(result)}). The latter
     is necessary since such handles may have sizes different from a pointer.
+
+    \note This function must only be called on the render thread.
  */
 void *QSGRendererInterface::getResource(Resource resource) const
 {
@@ -109,6 +116,8 @@ void *QSGRendererInterface::getResource(Resource resource) const
     Queries a graphics resource. \a resource is a backend-specific key. This
     allows supporting any future resources that are not listed in the
     Resource enum.
+
+    \note This function must only be called on the render thread.
  */
 void *QSGRendererInterface::getResource(const char *resource) const
 {
diff --git a/src/quick/scenegraph/qsgadaptationlayer.cpp b/src/quick/scenegraph/qsgadaptationlayer.cpp
index e8ef6befcd..b0259c50b0 100644
--- a/src/quick/scenegraph/qsgadaptationlayer.cpp
+++ b/src/quick/scenegraph/qsgadaptationlayer.cpp
@@ -519,4 +519,30 @@ void QSGNodeVisitorEx::visitChildren(QSGNode *node)
     }
 }
 
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug debug, const QSGGuiThreadShaderEffectManager::ShaderInfo::InputParameter &p)
+{
+    debug << p.semanticName << p.semanticIndex;
+    return debug;
+}
+QDebug operator<<(QDebug debug, const QSGGuiThreadShaderEffectManager::ShaderInfo::Variable &v)
+{
+    debug << v.name;
+    switch (v.type) {
+    case QSGGuiThreadShaderEffectManager::ShaderInfo::Constant:
+        debug << "cvar" << "offset" << v.offset << "size" << v.size;
+        break;
+    case QSGGuiThreadShaderEffectManager::ShaderInfo::Sampler:
+        debug << "sampler" << "bindpoint" << v.bindPoint;
+        break;
+    case QSGGuiThreadShaderEffectManager::ShaderInfo::Texture:
+        debug << "texture" << "bindpoint" << v.bindPoint;
+        break;
+    default:
+        break;
+    }
+    return debug;
+}
+#endif
+
 QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/qsgadaptationlayer_p.h b/src/quick/scenegraph/qsgadaptationlayer_p.h
index 78bb07599f..5155cdd719 100644
--- a/src/quick/scenegraph/qsgadaptationlayer_p.h
+++ b/src/quick/scenegraph/qsgadaptationlayer_p.h
@@ -223,6 +223,139 @@ Q_SIGNALS:
     void scheduledUpdateCompleted();
 };
 
+class Q_QUICK_PRIVATE_EXPORT QSGGuiThreadShaderEffectManager : public QObject
+{
+    Q_OBJECT
+
+public:
+    // Enum values must match ShaderEffect.
+    enum ShaderType {
+        GLSL,
+        HLSL,
+        Metal
+    };
+    enum ShaderCompilationType {
+        RuntimeCompilation = 0x01,
+        OfflineCompilation = 0x02
+    };
+    enum ShaderSourceType {
+        ShaderSourceString = 0x01,
+        ShaderSourceFile = 0x02,
+        ShaderByteCode = 0x04
+    };
+    enum Status {
+        Compiled,
+        Uncompiled,
+        Error
+    };
+
+    virtual ShaderType shaderType() const = 0;
+    virtual int shaderCompilationType() const = 0;
+    virtual int shaderSourceType() const = 0;
+
+    virtual bool hasSeparateSamplerAndTextureObjects() const = 0;
+
+    virtual QString log() const = 0;
+    virtual Status status() const = 0;
+
+    struct ShaderInfo {
+        enum Type {
+            TypeVertex,
+            TypeFragment,
+            TypeOther
+        };
+        enum VariableType {
+            Constant, // cbuffer members or uniforms
+            Sampler,
+            Texture // for APIs with separate texture and sampler objects
+        };
+        struct InputParameter {
+            InputParameter() : semanticIndex(0) { }
+            // Semantics use the D3D keys (POSITION, TEXCOORD).
+            // Attribute name based APIs can map based on pre-defined names.
+            QByteArray semanticName;
+            int semanticIndex;
+        };
+        struct Variable {
+            Variable() : type(Constant), offset(0), size(0), bindPoint(0) { }
+            VariableType type;
+            QByteArray name;
+            uint offset; // for cbuffer members
+            uint size; // for cbuffer members
+            int bindPoint; // for textures and samplers; for register-based APIs
+        };
+
+        QByteArray blob; // source or bytecode
+        Type type;
+        QVector<InputParameter> inputParameters;
+        QVector<Variable> variables;
+    };
+
+    virtual bool reflect(const QByteArray &src, ShaderInfo *result) = 0;
+
+Q_SIGNALS:
+    void textureChanged();
+    void logAndStatusChanged();
+};
+
+#ifndef QT_NO_DEBUG_STREAM
+Q_QUICK_PRIVATE_EXPORT QDebug operator<<(QDebug debug, const QSGGuiThreadShaderEffectManager::ShaderInfo::InputParameter &p);
+Q_QUICK_PRIVATE_EXPORT QDebug operator<<(QDebug debug, const QSGGuiThreadShaderEffectManager::ShaderInfo::Variable &v);
+#endif
+
+class Q_QUICK_PRIVATE_EXPORT QSGShaderEffectNode : public QSGVisitableNode
+{
+public:
+    enum DirtyShaderFlag {
+        DirtyShaderVertex = 0x01,
+        DirtyShaderFragment = 0x02,
+        DirtyShaderConstant = 0x04,
+        DirtyShaderTexture = 0x08,
+        DirtyShaderGeometry = 0x10,
+        DirtyShaderMesh = 0x20
+    };
+    Q_DECLARE_FLAGS(DirtyShaderFlags, DirtyShaderFlag)
+
+    enum CullMode { // must match ShaderEffect
+        NoCulling,
+        BackFaceCulling,
+        FrontFaceCulling
+    };
+
+    struct VariableData {
+        enum SpecialType { None, Unused, SubRect, Opacity, Matrix, Source };
+
+        QVariant value;
+        SpecialType specialType;
+    };
+
+    struct ShaderData {
+        ShaderData() : valid(false) { }
+        bool valid;
+        QSGGuiThreadShaderEffectManager::ShaderInfo shaderInfo;
+        QVector<VariableData> varData;
+    };
+
+    struct SyncData {
+        DirtyShaderFlags dirty;
+        CullMode cullMode;
+        bool blending;
+        bool supportsAtlasTextures;
+        ShaderData *vertexShader;
+        ShaderData *fragmentShader;
+    };
+
+    // Each ShaderEffect item has one node (render thread) and one manager (gui thread).
+    QSGShaderEffectNode(QSGGuiThreadShaderEffectManager *) { }
+
+    virtual QRectF normalizedTextureSubRect() const = 0;
+    virtual void sync(SyncData *syncData) = 0;
+
+    void accept(QSGNodeVisitorEx *visitor) override { if (visitor->visit(this)) visitor->visitChildren(this); visitor->endVisit(this); }
+};
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(QSGShaderEffectNode::DirtyShaderFlags)
+
 class Q_QUICK_PRIVATE_EXPORT QSGGlyphNode : public QSGVisitableNode
 {
 public:
diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index 0f0a7be3b2..27d0f01753 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -277,11 +277,29 @@ QSGRectangleNode *QSGContext::createRectangleNode(const QRectF &rect, const QCol
     return node;
 }
 
+/*!
+    Creates a new shader effect helper instance. This function is called on the
+    gui thread, unlike the others. This is necessary in order to provide
+    adaptable, backend-specific shader effect functionality to the gui thread too.
+ */
+QSGGuiThreadShaderEffectManager *QSGContext::createGuiThreadShaderEffectManager()
+{
+    return nullptr;
+}
 
 /*!
-    Creates a new animation driver.
+    Creates a new shader effect node. The default of returning nullptr is
+    valid as long as the backend does not claim SupportsShaderEffectNode or
+    ignoring ShaderEffect elements is acceptable.
  */
+QSGShaderEffectNode *QSGContext::createShaderEffectNode(QSGRenderContext *, QSGGuiThreadShaderEffectManager *)
+{
+    return nullptr;
+}
 
+/*!
+    Creates a new animation driver.
+ */
 QAnimationDriver *QSGContext::createAnimationDriver(QObject *parent)
 {
     return new QSGAnimationDriver(parent);
@@ -296,6 +314,12 @@ QSize QSGContext::minimumFBOSize() const
     return QSize(1, 1);
 }
 
+/*!
+    Returns a pointer to the (presumably) global renderer interface.
+
+    \note This function may be called on the gui thread in order to get access
+    to QSGRendererInterface::graphicsAPI().
+ */
 QSGRendererInterface *QSGContext::rendererInterface(QSGRenderContext *renderContext)
 {
     Q_UNUSED(renderContext);
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index 19a8636f19..2139377ebb 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -83,6 +83,8 @@ class QSGDistanceFieldGlyphCacheManager;
 class QSGContext;
 class QQuickPaintedItem;
 class QSGRendererInterface;
+class QSGShaderEffectNode;
+class QSGGuiThreadShaderEffectManager;
 
 Q_DECLARE_LOGGING_CATEGORY(QSG_LOG_TIME_RENDERLOOP)
 Q_DECLARE_LOGGING_CATEGORY(QSG_LOG_TIME_COMPILATION)
@@ -166,6 +168,9 @@ public:
     virtual QSGGlyphNode *createGlyphNode(QSGRenderContext *rc, bool preferNativeGlyphNode) = 0;
     virtual QSGNinePatchNode *createNinePatchNode() = 0;
     virtual QSGLayer *createLayer(QSGRenderContext *renderContext) = 0;
+    virtual QSGGuiThreadShaderEffectManager *createGuiThreadShaderEffectManager();
+    virtual QSGShaderEffectNode *createShaderEffectNode(QSGRenderContext *renderContext,
+                                                        QSGGuiThreadShaderEffectManager *mgr);
     virtual QAnimationDriver *createAnimationDriver(QObject *parent);
 
     virtual QSize minimumFBOSize() const;
diff --git a/src/quick/scenegraph/qsgcontextplugin_p.h b/src/quick/scenegraph/qsgcontextplugin_p.h
index 779dca62fc..08c3d21408 100644
--- a/src/quick/scenegraph/qsgcontextplugin_p.h
+++ b/src/quick/scenegraph/qsgcontextplugin_p.h
@@ -65,7 +65,7 @@ class QSGRenderLoop;
 struct Q_QUICK_PRIVATE_EXPORT QSGContextFactoryInterface : public QFactoryInterface
 {
     enum Flag {
-        SupportsShaderEffectV2 = 0x01
+        SupportsShaderEffectNode = 0x01
     };
     Q_DECLARE_FLAGS(Flags, Flag)