rhi: Add a --transparent option to manual tests

This will also cause clearing to 0,0,0,0.

Essential in order to allow fast testing of window transparency
issues in combination with QRhi and the various backends.

Change-Id: Iee2763c1d06f1d3e5d59a9142abaf30fab1dc543
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

tests/manual/rhi/compressedtexture_bc1/compressedtexture_bc1.cpp

@@ -182,7 +182,7 @@ void Window::customRender()
     QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
 
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });

tests/manual/rhi/compressedtexture_bc1_subupload/compressedtexture_bc1_subupload.cpp

@@ -197,7 +197,7 @@ void Window::customRender()
     QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
 
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });

tests/manual/rhi/computebuffer/computebuffer.cpp

@@ -195,7 +195,7 @@ void Window::customRender()
     cb->endComputePass();
 
     // graphics pass
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 });
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 });
     cb->setGraphicsPipeline(d.graphicsPipeline);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     QRhiCommandBuffer::VertexInput vbufBinding(d.sbuf, 0);

tests/manual/rhi/computeimage/computeimage.cpp

@@ -217,7 +217,7 @@ void Window::customRender()
     cb->dispatch(d.imageSize.width() / 16, d.imageSize.height() / 16, 1);
     cb->endComputePass();
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 });
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 });
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     cb->setShaderResources();

tests/manual/rhi/cubemap/cubemap.cpp

@@ -168,7 +168,7 @@ void Window::customRender()
     // no translation
     u->updateDynamicBuffer(d.ubuf, 0, 64, mvp.constData());
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport(QRhiViewport(0, 0, outputSizeInPixels.width(), outputSizeInPixels.height()));
     cb->setShaderResources();

tests/manual/rhi/cubemap_scissor/cubemap_scissor.cpp

@@ -221,7 +221,7 @@ void Window::customRender()
     // no translation
     u->updateDynamicBuffer(d.ubuf, 0, 64, mvp.constData());
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport(QRhiViewport(0, 0, outputSizeInPixels.width(), outputSizeInPixels.height()));
 

tests/manual/rhi/floattexture/floattexture.cpp

@@ -317,7 +317,7 @@ void Window::customRender()
     }
 
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     cb->setShaderResources();

tests/manual/rhi/instancing/instancing.cpp

@@ -161,7 +161,7 @@ void Window::customRender()
         u->updateDynamicBuffer(d.ubuf, 0, 64, mvp.constData());
     }
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     cb->setShaderResources();

tests/manual/rhi/mrt/mrt.cpp

@@ -283,7 +283,7 @@ void Window::customRender()
     }
 
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     vbufBinding.second = 0;

tests/manual/rhi/msaarenderbuffer/msaarenderbuffer.cpp

@@ -248,7 +248,7 @@ void Window::customRender()
 
     // onscreen (quad)
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 });
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 });
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     cb->setShaderResources();

tests/manual/rhi/msaatexture/msaatexture.cpp

@@ -315,7 +315,7 @@ void Window::customRender()
 
     // onscreen
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 });
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 });
     cb->setGraphicsPipeline(d.psLeft); // showing the non-msaa version
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     cb->setShaderResources();

tests/manual/rhi/shadowmap/shadowmap.cpp

@@ -296,7 +296,7 @@ void Window::customRender()
     cb->endPass();
 
     // main pass
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 });
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 });
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     enqueueScene(cb, d.srb, oneRoundedUniformBlockSize, 0);

tests/manual/rhi/shared/examplefw.h

@@ -127,6 +127,7 @@ QRhiSwapChain::Flags scFlags = 0;
 QRhi::BeginFrameFlags beginFrameFlags = 0;
 QRhi::EndFrameFlags endFrameFlags = 0;
 int framesUntilTdr = -1;
+bool transparentBackground = false;
 
 class Window : public QWindow
 {
@@ -167,6 +168,8 @@ protected:
     QOffscreenSurface *m_fallbackSurface = nullptr;
 #endif
 
+    QColor m_clearColor;
+
     friend int main(int, char**);
 };
 
@@ -194,6 +197,8 @@ Window::Window()
     default:
         break;
     }
+
+    m_clearColor = transparentBackground ? Qt::transparent : QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f);
 }
 
 Window::~Window()
@@ -477,6 +482,9 @@ int main(int argc, char **argv)
     QCommandLineOption swOption(QLatin1String("software"), QLatin1String("Prefer a software renderer when choosing the adapter. "
                                                                          "Only applicable with some APIs and platforms."));
     cmdLineParser.addOption(swOption);
+    // Allow testing having a semi-transparent window.
+    QCommandLineOption transparentOption(QLatin1String("transparent"), QLatin1String("Make background transparent"));
+    cmdLineParser.addOption(transparentOption);
 
     cmdLineParser.process(app);
     if (cmdLineParser.isSet(nullOption))
@@ -493,6 +501,11 @@ int main(int argc, char **argv)
     qDebug("Selected graphics API is %s", qPrintable(graphicsApiName()));
     qDebug("This is a multi-api example, use command line arguments to override:\n%s", qPrintable(cmdLineParser.helpText()));
 
+    if (cmdLineParser.isSet(transparentOption)) {
+        transparentBackground = true;
+        scFlags |= QRhiSwapChain::SurfaceHasPreMulAlpha;
+    }
+
 #ifdef EXAMPLEFW_PREINIT
     void preInit();
     preInit();
@@ -508,6 +521,9 @@ int main(int argc, char **argv)
         fmt.setSwapInterval(0);
     if (scFlags.testFlag(QRhiSwapChain::sRGB))
         fmt.setColorSpace(QSurfaceFormat::sRGBColorSpace);
+    // Exception: The alpha size is not necessarily OpenGL specific.
+    if (transparentBackground)
+        fmt.setAlphaBufferSize(8);
     QSurfaceFormat::setDefaultFormat(fmt);
 
     // Vulkan setup.

tests/manual/rhi/texuploads/texuploads.cpp

@@ -296,7 +296,7 @@ void Window::customRender()
     QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
     const QSize outputSizeInPixels = m_sc->currentPixelSize();
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
 
     cb->setGraphicsPipeline(d.ps);
     cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });

tests/manual/rhi/triquadcube/triquadcube.cpp

@@ -230,7 +230,7 @@ void Window::customRender()
     if (!d.onScreenOnly)
         d.liveTexCubeRenderer.queueResourceUpdates(u);
 
-    cb->beginPass(m_sc->currentFrameRenderTarget(), QColor::fromRgbF(0.4f, 0.7f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
     cb->debugMarkBegin(QByteArrayLiteral("Triangle"));
     d.triRenderer.queueDraw(cb, outputSize);
     cb->debugMarkEnd();