D3D12: Add support for shader sources in files

Now we support all combinations: source strings, HLSL source in files
and bytecode in files. The type of file contents is detected
automatically.

Change-Id: Id6ab269df52463fb95a9a1ef2598ed5576a873d3
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

3 files changed, 37 insertions, 16 deletions

diff --git a/src/plugins/scenegraph/d3d12/qsgd3d12rendercontext.cpp b/src/plugins/scenegraph/d3d12/qsgd3d12rendercontext.cpp
index 7e62421380..84b12303d9 100644
--- a/src/plugins/scenegraph/d3d12/qsgd3d12rendercontext.cpp
+++ b/src/plugins/scenegraph/d3d12/qsgd3d12rendercontext.cpp
@@ -153,7 +153,7 @@ QSGRendererInterface::ShaderCompilationTypes QSGD3D12RenderContext::shaderCompil
 
 QSGRendererInterface::ShaderSourceTypes QSGD3D12RenderContext::shaderSourceType() const
 {
-    return ShaderSourceString | ShaderByteCode;
+    return ShaderSourceString | ShaderSourceFile | ShaderByteCode;
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/scenegraph/d3d12/qsgd3d12shadereffectnode.cpp b/src/plugins/scenegraph/d3d12/qsgd3d12shadereffectnode.cpp
index baf7571910..d459ec29ab 100644
--- a/src/plugins/scenegraph/d3d12/qsgd3d12shadereffectnode.cpp
+++ b/src/plugins/scenegraph/d3d12/qsgd3d12shadereffectnode.cpp
@@ -840,16 +840,19 @@ void QSGD3D12ShaderCompileTask::run()
     emit mgr->logAndStatusChanged();
 }
 
+static const int BYTECODE_MAGIC = 0x43425844; // 'DXBC'
+
 void QSGD3D12GuiThreadShaderEffectManager::prepareShaderCode(ShaderInfo::Type typeHint, const QByteArray &src, ShaderInfo *result)
 {
     // The D3D12 backend's ShaderEffect implementation supports both HLSL
-    // source strings and bytecode in files as input. The latter is strongly
-    // recommended, but in order to make ShaderEffect users' (and
-    // qtgraphicaleffects') life easier, and since we link to d3dcompiler
+    // source strings and bytecode or source in files as input. Bytecode is
+    // strongly recommended, but in order to make ShaderEffect users' (and
+    // anything that stiches shader strings together dynamically, e.g.
+    // qtgraphicaleffects) life easier, and since we link to d3dcompiler
     // anyways, compiling from source is also supported.
 
-    // For simplicity, assume that file = bytecode, string = HLSL.
-    QUrl srcUrl(src);
+    QByteArray shaderSourceCode = src;
+    QUrl srcUrl(QString::fromUtf8(src));
     if (!srcUrl.scheme().compare(QLatin1String("qrc"), Qt::CaseInsensitive) || srcUrl.isLocalFile()) {
         if (!m_fileSelector) {
             m_fileSelector = new QFileSelector(this);
@@ -862,16 +865,25 @@ void QSGD3D12GuiThreadShaderEffectManager::prepareShaderCode(ShaderInfo::Type ty
             emit shaderCodePrepared(false, typeHint, src, result);
             return;
         }
-        result->blob = f.readAll();
+        QByteArray blob = f.readAll();
         f.close();
-        const bool ok = reflect(result);
-        m_status = ok ? Compiled : Error;
-        emit shaderCodePrepared(ok, typeHint, src, result);
-        emit logAndStatusChanged();
-        return;
+        if (blob.size() > 4) {
+            const quint32 *p = reinterpret_cast<const quint32 *>(blob.constData());
+            if (*p == BYTECODE_MAGIC) {
+                // already compiled D3D bytecode, skip straight to reflection
+                result->blob = blob;
+                const bool ok = reflect(result);
+                m_status = ok ? Compiled : Error;
+                emit shaderCodePrepared(ok, typeHint, src, result);
+                emit logAndStatusChanged();
+                return;
+            }
+            // assume the file contained HLSL source code
+            shaderSourceCode = blob;
+        }
     }
 
-    QThreadPool::globalInstance()->start(new QSGD3D12ShaderCompileTask(this, typeHint, src, result));
+    QThreadPool::globalInstance()->start(new QSGD3D12ShaderCompileTask(this, typeHint, shaderSourceCode, result));
 }
 
 bool QSGD3D12GuiThreadShaderEffectManager::reflect(ShaderInfo *result)
diff --git a/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc b/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc
index d506e68d6a..fbbc947c4c 100644
--- a/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc
+++ b/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc
@@ -236,9 +236,18 @@ different than with OpenGL.
 With D3D12, these strings can either be an URL for a local file or a file in
 the resource system, or a HLSL source string. The former indicates that the
 file in question contains pre-compiled D3D shader bytecode generated by the
-\c fxc tool.
-
-See the ShaderEffect documentation for a detailed description.
+\c fxc tool, or, alternatively, HLSL source code. The type of the file is detected
+automatically. This means that the D3D12 backend supports all options from
+GraphicsInfo.shaderCompilationType and GraphicsInfo.shaderSourceType.
+
+Unlike OpenGL, there is a QFileSelector with the extra selector \c hlsl used
+whenever opening a file. This allows easy creation of ShaderEffect items that
+are functional across both backends, for example by placing the GLSL source
+code into "shaders/effect.frag", the HLSL source code or - preferably -
+pre-compiled bytecode into "shaders/+hlsl/effect.frag", while simply writing
+\c{fragmentShader: "qrc:shaders/effect.frag"} in QML.
+
+See the ShaderEffect documentation for more details.
 
 \section2 Unsupported Features