Vulkan: Handle 0-sized viewports

Issue exposed by a transform feedback test. Since we already create a scissor to match the viewport (be it 0-sized or not), we can create the Vulkan viewport with a small width/height if they are 0, as that's not allowed by Vulkan. Bug: angleproject:3205 Change-Id: Ib23d8b9f5e84447be2c4b7e8aff805e7d9e57323 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1665352 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>

Vulkan: Handle 0-sized viewports
371d95b8 · Shahbaz Youssefi · Commit Bot · 067687f4 · 371d95b8
Commit 371d95b8 authored Jun 18, 2019 by Shahbaz Youssefi Committed by Commit Bot Jun 21, 2019
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vk_cache_utils.cpp src/libANGLE/renderer/vulkan/vk_cache_utils.cpp +13 -1

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--- a/src/libANGLE/renderer/vulkan/vk_cache_utils.cpp
+++ b/src/libANGLE/renderer/vulkan/vk_cache_utils.cpp
@@ -677,10 +677,22 @@ angle::Result GraphicsPipelineDesc::initializePipeline(
    // Set initial viewport and scissor state.
+    // 0-sized viewports are invalid in Vulkan.  We always use a scissor that at least matches the
+    // requested viewport, so it's safe to adjust the viewport size here.
+    VkViewport viewport = mViewport;
+    if (viewport.width == 0)
+    {
+        viewport.width = 1;
+    }
+    if (viewport.height == 0)
+    {
+        viewport.height = 1;
+    }
    viewportState.sType         = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
    viewportState.flags         = 0;
    viewportState.viewportCount = 1;
-    viewportState.pViewports    = &mViewport;
+    viewportState.pViewports    = &viewport;
    viewportState.scissorCount  = 1;
    viewportState.pScissors     = &mScissor;