Add the graphics api independent scenegraph port

Opt in via environment variables:
QSG_RHI=1 -> enable using QRhi instead of GL
QSG_RHI_BACKEND -> set to vulkan, metal, d3d11, gl to override the default
(the default is d3d11 on Windows, metal on Mac, gl elsewhere)

Or force a given rhi backend via the existing
QQuickWindow::setSceneGraphBackend().

Otherwise the default behavior is the same as before, the rhi code path
is never active by default.

-no-opengl builds are supported in the sense that they work and default
to the software backend. However, the rhi code path cannot currently be
used in such builds, even though QRhi from qtbase is fully functional
with Vulkan, D3D, or Metal even when qtbase was configured with
-no-opengl. This cannot be utilized by Quick atm due to OpenGL usage
being all over the place in the sources corresponding to the default
backend, and those host the rhi code path as well. This will be cleaned up
hopefully in Qt 6, with the removal all direct OpenGL usage.

Other env.vars.:
QSG_RHI_DEBUG_LAYER=1 -> enable D3D debug or Vulkan validation layer
(assuming the system is set up for this)
QSG_RHI_SHADEREFFECT_DEBUG=1 -> print stuff from ShaderEffect
QSG_SAMPLES=1,2,4,... -> MSAA sample count (but QSurfaceFormat works too)
QT_D3D_ADAPTER_INDEX=0,1,... -> D3D adapter index
QT_VK_PHYSICAL_DEVICE_INDEX=0,1,... -> Vulkan physical device index
QSG_RHI_UINT32_INDEX=1 -> always use uint index data (both
merged/unmerged, convert when needed - with some rhi backends this is
implicit)
QSG_RENDER_LOOP -> to override the render loop as usual. The default
with RHI is threaded for Metal, threaded for Vulkan on Windows, basic
for Vulkan on Linux and Android (to be checked later), while the existing
rules apply for OpenGL.

Not supported when running with QRhi:
  - particles
  - compressed atlases (though this is transparent to the apps)
  - QSGRenderNode
  - QQuickRenderControl
  - QQuickFramebufferObject
  - certain QQuickWindow functionality that depends directly on OpenGL
  - anisotropic filtering for textures
  - native text may lack some gamma correction
  - QSGEngine applicability unclear
  - some QML profiler logs may be incorrect or irrelevant

Change-Id: I7822e99ad79e342e4166275da6e9e66498d76521
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 426 insertions, 0 deletions

diff --git a/examples/quick/scenegraph/d3d11underqml/d3d11squircle.cpp b/examples/quick/scenegraph/d3d11underqml/d3d11squircle.cpp
new file mode 100644
index 0000000000..f05bf2f843
--- /dev/null
+++ b/examples/quick/scenegraph/d3d11underqml/d3d11squircle.cpp
@@ -0,0 +1,426 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "d3d11squircle.h"
+#include <QtCore/QRunnable>
+#include <QtQuick/QQuickWindow>
+
+#include <d3d11.h>
+#include <d3dcompiler.h>
+
+class SquircleRenderer : public QObject
+{
+    Q_OBJECT
+public:
+    SquircleRenderer();
+    ~SquircleRenderer();
+
+    void setT(qreal t) { m_t = t; }
+    void setViewportSize(const QSize &size) { m_viewportSize = size; }
+    void setWindow(QQuickWindow *window) { m_window = window; }
+
+public slots:
+    void frameStart();
+    void mainPassRecordingStart();
+
+private:
+    enum Stage {
+        VertexStage,
+        FragmentStage
+    };
+    void prepareShader(Stage stage);
+    QByteArray compileShader(Stage stage,
+                             const QByteArray &source,
+                             const QByteArray &entryPoint);
+    void init();
+
+    QSize m_viewportSize;
+    qreal m_t;
+    QQuickWindow *m_window;
+
+    ID3D11Device *m_device = nullptr;
+    ID3D11DeviceContext *m_context = nullptr;
+    QByteArray m_vert;
+    QByteArray m_vertEntryPoint;
+    QByteArray m_frag;
+    QByteArray m_fragEntryPoint;
+
+    bool m_initialized = false;
+    ID3D11Buffer *m_vbuf = nullptr;
+    ID3D11Buffer *m_cbuf = nullptr;
+    ID3D11VertexShader *m_vs = nullptr;
+    ID3D11PixelShader *m_ps = nullptr;
+    ID3D11InputLayout *m_inputLayout = nullptr;
+    ID3D11RasterizerState *m_rastState = nullptr;
+    ID3D11DepthStencilState *m_dsState = nullptr;
+    ID3D11BlendState *m_blendState = nullptr;
+};
+
+D3D11Squircle::D3D11Squircle()
+    : m_t(0)
+    , m_renderer(nullptr)
+{
+    connect(this, &QQuickItem::windowChanged, this, &D3D11Squircle::handleWindowChanged);
+}
+
+void D3D11Squircle::setT(qreal t)
+{
+    if (t == m_t)
+        return;
+    m_t = t;
+    emit tChanged();
+    if (window())
+        window()->update();
+}
+
+void D3D11Squircle::handleWindowChanged(QQuickWindow *win)
+{
+    if (win) {
+        connect(win, &QQuickWindow::beforeSynchronizing, this, &D3D11Squircle::sync, Qt::DirectConnection);
+        connect(win, &QQuickWindow::sceneGraphInvalidated, this, &D3D11Squircle::cleanup, Qt::DirectConnection);
+
+        // Ensure we start with cleared to black. The squircle's blend mode relies on this.
+        win->setColor(Qt::black);
+    }
+}
+
+SquircleRenderer::SquircleRenderer()
+    : m_t(0)
+{
+}
+
+// The safe way to release custom graphics resources it to both connect to
+// sceneGraphInvalidated() and implement releaseResources(). To support
+// threaded render loops the latter performs the SquircleRenderer destruction
+// via scheduleRenderJob(). Note that the D3D11Squircle may be gone by the time
+// the QRunnable is invoked.
+
+void D3D11Squircle::cleanup()
+{
+    delete m_renderer;
+    m_renderer = nullptr;
+}
+
+class CleanupJob : public QRunnable
+{
+public:
+    CleanupJob(SquircleRenderer *renderer) : m_renderer(renderer) { }
+    void run() override { delete m_renderer; }
+private:
+    SquircleRenderer *m_renderer;
+};
+
+void D3D11Squircle::releaseResources()
+{
+    window()->scheduleRenderJob(new CleanupJob(m_renderer), QQuickWindow::BeforeSynchronizingStage);
+    m_renderer = nullptr;
+}
+
+SquircleRenderer::~SquircleRenderer()
+{
+    qDebug("cleanup");
+
+    if (m_vs)
+        m_vs->Release();
+
+    if (m_ps)
+        m_ps->Release();
+
+    if (m_vbuf)
+        m_vbuf->Release();
+
+    if (m_cbuf)
+        m_cbuf->Release();
+
+    if (m_inputLayout)
+        m_inputLayout->Release();
+
+    if (m_rastState)
+        m_rastState->Release();
+
+    if (m_dsState)
+        m_dsState->Release();
+
+    if (m_blendState)
+        m_blendState->Release();
+}
+
+void D3D11Squircle::sync()
+{
+    if (!m_renderer) {
+        m_renderer = new SquircleRenderer;
+        connect(window(), &QQuickWindow::beforeRendering, m_renderer, &SquircleRenderer::frameStart, Qt::DirectConnection);
+        connect(window(), &QQuickWindow::beforeRenderPassRecording, m_renderer, &SquircleRenderer::mainPassRecordingStart, Qt::DirectConnection);
+    }
+    m_renderer->setViewportSize(window()->size() * window()->devicePixelRatio());
+    m_renderer->setT(m_t);
+    m_renderer->setWindow(window());
+}
+
+void SquircleRenderer::frameStart()
+{
+    QSGRendererInterface *rif = m_window->rendererInterface();
+
+    // We are not prepared for anything other than running with the RHI and its D3D11 backend.
+    Q_ASSERT(rif->graphicsApi() == QSGRendererInterface::Direct3D11Rhi);
+
+    m_device = reinterpret_cast<ID3D11Device *>(rif->getResource(m_window, QSGRendererInterface::DeviceResource));
+    Q_ASSERT(m_device);
+    m_context = reinterpret_cast<ID3D11DeviceContext *>(rif->getResource(m_window, QSGRendererInterface::DeviceContextResource));
+    Q_ASSERT(m_context);
+
+    if (m_vert.isEmpty())
+        prepareShader(VertexStage);
+    if (m_frag.isEmpty())
+        prepareShader(FragmentStage);
+
+    if (!m_initialized)
+        init();
+}
+
+static const float vertices[] = {
+    -1, -1,
+    1, -1,
+    -1, 1,
+    1, 1
+};
+
+void SquircleRenderer::mainPassRecordingStart()
+{
+    m_window->beginExternalCommands();
+
+    D3D11_MAPPED_SUBRESOURCE mp;
+    // will copy the entire constant buffer every time -> pass WRITE_DISCARD -> prevent pipeline stalls
+    HRESULT hr = m_context->Map(m_cbuf, 0, D3D11_MAP_WRITE_DISCARD, 0, &mp);
+    if (SUCCEEDED(hr)) {
+        float t = m_t;
+        memcpy(mp.pData, &t, 4);
+        m_context->Unmap(m_cbuf, 0);
+    } else {
+        qFatal("Failed to map constant buffer: 0x%x", hr);
+    }
+
+    D3D11_VIEWPORT v;
+    v.TopLeftX = 0;
+    v.TopLeftY = 0;
+    v.Width = m_viewportSize.width();
+    v.Height = m_viewportSize.height();
+    v.MinDepth = 0;
+    v.MaxDepth = 1;
+    m_context->RSSetViewports(1, &v);
+
+    m_context->VSSetShader(m_vs, nullptr, 0);
+    m_context->PSSetShader(m_ps, nullptr, 0);
+    m_context->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP);
+    m_context->IASetInputLayout(m_inputLayout);
+    m_context->OMSetDepthStencilState(m_dsState, 0);
+    float blendConstants[] = { 1, 1, 1, 1 };
+    m_context->OMSetBlendState(m_blendState, blendConstants, 0xFFFFFFFF);
+    m_context->RSSetState(m_rastState);
+
+    const UINT stride = 2 * sizeof(float); // vec2
+    const UINT offset = 0;
+    m_context->IASetVertexBuffers(0, 1, &m_vbuf, &stride, &offset);
+    m_context->PSSetConstantBuffers(0, 1, &m_cbuf);
+
+    m_context->Draw(4, 0);
+
+    m_window->endExternalCommands();
+}
+
+void SquircleRenderer::prepareShader(Stage stage)
+{
+    QString filename;
+    if (stage == VertexStage) {
+        filename = QLatin1String(":/scenegraph/d3d11underqml/squircle.vert");
+    } else {
+        Q_ASSERT(stage == FragmentStage);
+        filename = QLatin1String(":/scenegraph/d3d11underqml/squircle.frag");
+    }
+    QFile f(filename);
+    if (!f.open(QIODevice::ReadOnly))
+        qFatal("Failed to read shader %s", qPrintable(filename));
+
+    const QByteArray contents = f.readAll();
+
+    if (stage == VertexStage) {
+        m_vert = contents;
+        Q_ASSERT(!m_vert.isEmpty());
+        m_vertEntryPoint = QByteArrayLiteral("main");
+    } else {
+        m_frag = contents;
+        Q_ASSERT(!m_frag.isEmpty());
+        m_fragEntryPoint = QByteArrayLiteral("main");
+    }
+}
+
+QByteArray SquircleRenderer::compileShader(Stage stage,
+                                           const QByteArray &source,
+                                           const QByteArray &entryPoint)
+{
+    const char *target;
+    switch (stage) {
+    case VertexStage:
+        target = "vs_5_0";
+        break;
+    case FragmentStage:
+        target = "ps_5_0";
+        break;
+    default:
+        qFatal("Unknown shader stage %d", stage);
+        return QByteArray();
+    }
+
+    ID3DBlob *bytecode = nullptr;
+    ID3DBlob *errors = nullptr;
+    HRESULT hr = D3DCompile(source.constData(), source.size(),
+                            nullptr, nullptr, nullptr,
+                            entryPoint.constData(), target, 0, 0, &bytecode, &errors);
+    if (FAILED(hr) || !bytecode) {
+        qWarning("HLSL shader compilation failed: 0x%x", uint(hr));
+        if (errors) {
+            const QByteArray msg(static_cast<const char *>(errors->GetBufferPointer()),
+                                 errors->GetBufferSize());
+            errors->Release();
+            qWarning("%s", msg.constData());
+        }
+        return QByteArray();
+    }
+
+    QByteArray result;
+    result.resize(bytecode->GetBufferSize());
+    memcpy(result.data(), bytecode->GetBufferPointer(), result.size());
+    bytecode->Release();
+
+    return result;
+}
+
+void SquircleRenderer::init()
+{
+    qDebug("init");
+    m_initialized = true;
+
+    const QByteArray vs = compileShader(VertexStage, m_vert, m_vertEntryPoint);
+    const QByteArray fs = compileShader(FragmentStage, m_frag, m_fragEntryPoint);
+
+    HRESULT hr = m_device->CreateVertexShader(vs.constData(), vs.size(), nullptr, &m_vs);
+    if (FAILED(hr))
+        qFatal("Failed to create vertex shader: 0x%x", hr);
+
+    hr = m_device->CreatePixelShader(fs.constData(), fs.size(), nullptr, &m_ps);
+    if (FAILED(hr))
+        qFatal("Failed to create pixel shader: 0x%x", hr);
+
+    D3D11_BUFFER_DESC bufDesc;
+    memset(&bufDesc, 0, sizeof(bufDesc));
+    bufDesc.ByteWidth = sizeof(vertices);
+    bufDesc.Usage = D3D11_USAGE_DEFAULT;
+    bufDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
+    hr = m_device->CreateBuffer(&bufDesc, nullptr, &m_vbuf);
+    if (FAILED(hr))
+        qFatal("Failed to create buffer: 0x%x", hr);
+
+    m_context->UpdateSubresource(m_vbuf, 0, nullptr, vertices, 0, 0);
+
+    bufDesc.ByteWidth = 256;
+    bufDesc.Usage = D3D11_USAGE_DYNAMIC;
+    bufDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
+    bufDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
+    hr = m_device->CreateBuffer(&bufDesc, nullptr, &m_cbuf);
+    if (FAILED(hr))
+        qFatal("Failed to create buffer: 0x%x", hr);
+
+    D3D11_INPUT_ELEMENT_DESC inputDesc;
+    memset(&inputDesc, 0, sizeof(inputDesc));
+    // the output from SPIRV-Cross uses TEXCOORD<location> as the semantic
+    inputDesc.SemanticName = "TEXCOORD";
+    inputDesc.SemanticIndex = 0;
+    inputDesc.Format = DXGI_FORMAT_R32G32_FLOAT; // vec2
+    inputDesc.InputSlot = 0;
+    inputDesc.AlignedByteOffset = 0;
+    inputDesc.InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
+    hr = m_device->CreateInputLayout(&inputDesc, 1, vs.constData(), vs.size(), &m_inputLayout);
+    if (FAILED(hr))
+        qFatal("Failed to create input layout: 0x%x", hr);
+
+    D3D11_RASTERIZER_DESC rastDesc;
+    memset(&rastDesc, 0, sizeof(rastDesc));
+    rastDesc.FillMode = D3D11_FILL_SOLID;
+    rastDesc.CullMode = D3D11_CULL_NONE;
+    hr = m_device->CreateRasterizerState(&rastDesc, &m_rastState);
+    if (FAILED(hr))
+        qFatal("Failed to create rasterizer state: 0x%x", hr);
+
+    D3D11_DEPTH_STENCIL_DESC dsDesc;
+    memset(&dsDesc, 0, sizeof(dsDesc));
+    hr = m_device->CreateDepthStencilState(&dsDesc, &m_dsState);
+    if (FAILED(hr))
+        qFatal("Failed to create depth/stencil state: 0x%x", hr);
+
+    D3D11_BLEND_DESC blendDesc;
+    memset(&blendDesc, 0, sizeof(blendDesc));
+    blendDesc.IndependentBlendEnable = true;
+    D3D11_RENDER_TARGET_BLEND_DESC blend;
+    memset(&blend, 0, sizeof(blend));
+    blend.BlendEnable = true;
+    blend.SrcBlend = D3D11_BLEND_SRC_ALPHA;
+    blend.DestBlend = D3D11_BLEND_ONE;
+    blend.BlendOp = D3D11_BLEND_OP_ADD;
+    blend.SrcBlendAlpha = D3D11_BLEND_SRC_ALPHA;
+    blend.DestBlendAlpha = D3D11_BLEND_ONE;
+    blend.BlendOpAlpha = D3D11_BLEND_OP_ADD;
+    blend.RenderTargetWriteMask = D3D11_COLOR_WRITE_ENABLE_ALL;
+    blendDesc.RenderTarget[0] = blend;
+    hr = m_device->CreateBlendState(&blendDesc, &m_blendState);
+    if (FAILED(hr))
+        qFatal("Failed to create blend state: 0x%x", hr);
+}
+
+#include "d3d11squircle.moc"