Minor corrections in comments

examples/rhi/hellominimalcrossgfxtriangle/hellominimalcrossgfxtriangle.cpp

@@ -433,7 +433,10 @@ void Window::render()
         m_newlyExposed = false;
     }
 
-    // Start a new frame. This is where we block when too far ahead of GPU/present.
+    // Start a new frame. This is where we block when too far ahead of
+    // GPU/present, and that's what throttles the thread to the refresh rate.
+    // (except for OpenGL where it happens either in endFrame or somewhere else
+    // depending on the GL implementation)
     QRhi::FrameOpResult r = m_r->beginFrame(m_sc);
     if (r == QRhi::FrameOpSwapChainOutOfDate) {
         resizeSwapChain();
@@ -476,11 +479,11 @@ void Window::render()
     QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
     const QSize outputSizeInPixels = m_sc->effectivePixelSize();
 
-    // Apply buffer/texture updates, clear, queue the renderpass begin (where applicable).
+    // Apply buffer updates, clear, start the renderpass (where applicable).
     m_r->beginPass(m_sc->currentFrameRenderTarget(), cb, { 0.4f, 0.7f, 0.0f, 1.0f }, { 1.0f, 0 }, u);
 
     m_r->setGraphicsPipeline(cb, m_ps);
-    m_r->setViewport(cb, QRhiViewport(0, 0, outputSizeInPixels.width(), outputSizeInPixels.height()));
+    m_r->setViewport(cb, { 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
     m_r->setVertexInput(cb, 0, { { m_vbuf, 0 } });
     m_r->draw(cb, 3);
 

src/rhi/qrhid3d11.cpp

@@ -319,7 +319,7 @@ void QRhiD3D11::setViewport(QRhiCommandBuffer *cb, const QRhiViewport &viewport)
     QD3D11CommandBuffer::Command cmd;
     cmd.cmd = QD3D11CommandBuffer::Command::Viewport;
     cmd.args.viewport.x = viewport.r.x();
-    // d3d expects top-left, QRhiScissor is bottom-left
+    // d3d expects top-left, QRhiViewport is bottom-left
     cmd.args.viewport.y = cbD->currentTarget->sizeInPixels().height() - (viewport.r.y() + viewport.r.w() - 1);
     cmd.args.viewport.y = viewport.r.y();
     cmd.args.viewport.w = viewport.r.z();

src/rhi/qrhimetal.mm

@@ -46,9 +46,9 @@
 QT_BEGIN_NAMESPACE
 
 /*
-    Metal backend. MRC. Double buffers and throttles to vsync. "Dynamic"
-    buffers are Shared (host visible) and duplicated (due to 2 frames in
-    flight), while "static" buffers are ###
+    Metal backend. Double buffers and throttles to vsync. "Dynamic" buffers are
+    Shared (host visible) and duplicated (due to 2 frames in flight), while
+    "static" buffers are Managed on macOS and Shared on iOS/tvOS.
 */
 
 #if __has_feature(objc_arc)
@@ -621,7 +621,9 @@ bool QMetalBuffer::build()
 
     const int roundedSize = m_usage.testFlag(QRhiBuffer::UniformBuffer) ? aligned(m_size, 256) : m_size;
 
-    MTLResourceOptions opts = MTLResourceStorageModeShared; // ### for now everything host visible and double buffered
+    // ### for now everything host visible and double buffered
+    // should instead use Managed on macOS for immutable/static
+    MTLResourceOptions opts = MTLResourceStorageModeShared;
 
     QRHI_RES_RHI(QRhiMetal);
     for (int i = 0; i < QMTL_FRAMES_IN_FLIGHT; ++i) {

src/rhi/qrhivulkan.cpp

@@ -2912,7 +2912,7 @@ bool QVkTextureRenderTarget::build()
 
 QRhiRenderTarget::Type QVkTextureRenderTarget::type() const
 {
-    return RtTexture; // this is a QVkTextureRenderTarget, owns fb and rp
+    return RtTexture;
 }
 
 QSize QVkTextureRenderTarget::sizeInPixels() const