Vulkan: Fix incorrect alignment logic in readPixels

Framebuffers previously assumed a readPixels buffer alignment of 4 bytes, which causes issues when attempting to read with a format larger than 4 bytes per pixel. Change the default alignment to match the size of the largest know Vulkan format Bug: angleproject:3731 Change-Id: I6cd26a99e6f3b2f30084d403630c17f51a0ecedf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1727731 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>

Vulkan: Fix incorrect alignment logic in readPixels
8a43b8c7 · Mohan Maiya · Commit Bot · a06d32dc · 8a43b8c7
Commit 8a43b8c7 authored Aug 02, 2019 by Mohan Maiya Committed by Commit Bot Aug 03, 2019
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FramebufferVk.cpp src/libANGLE/renderer/vulkan/FramebufferVk.cpp +7 -2

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--- a/src/libANGLE/renderer/vulkan/FramebufferVk.cpp
+++ b/src/libANGLE/renderer/vulkan/FramebufferVk.cpp
@@ -36,6 +36,11 @@ namespace
 constexpr unsigned int kEmulatedAlphaValue = 1;
 constexpr size_t kMinReadPixelsBufferSize = 128000;
+// Alignment value to accommodate the largest known, for now, uncompressed Vulkan format
+// VK_FORMAT_R64G64B64A64_SFLOAT
+constexpr size_t kReadPixelsBufferAlignment = 32;
 // Clear values are only used when loadOp=Clear is set in clearWithRenderPassOp.  When starting a
 // new render pass, the clear value is set to an unlikely value (bright pink) to stand out better
 // in case of a bug.
@@ -164,8 +169,8 @@ FramebufferVk::FramebufferVk(RendererVk *renderer,
                             WindowSurfaceVk *backbuffer)
    : FramebufferImpl(state), mBackbuffer(backbuffer), mActiveColorComponents(0)
 {
-    mReadPixelBuffer.init(renderer, VK_BUFFER_USAGE_TRANSFER_DST_BIT, 4, kMinReadPixelsBufferSize,
+    mReadPixelBuffer.init(renderer, VK_BUFFER_USAGE_TRANSFER_DST_BIT, kReadPixelsBufferAlignment,
-                          true);
+                          kMinReadPixelsBufferSize, true);
 }
 FramebufferVk::~FramebufferVk() = default;