Vulkan raster renderer: the screen's picture is not cleared while the frontend reads it

The screen's render pass clears and draws into an image the frontend was
handed before, on the queue the two share, and now depends on whatever read
it there - a shader, a compute upscaler, a copy - being done first, as the
per-pixel, SSAA and render to texture passes already do. A GPU that draws in
tiles showed tiles of the next frame with only its opaque polygons drawn, the
translucent ones over them missing, per triangle and per strip alike.

tools/rend/speckle_test.sh checks the dependency in the sources.

core/rend/vulkan/drawer.cpp

@@ -927,6 +927,14 @@ void ScreenDrawer::Init(SamplerManager *samplerManager, ShaderManager *shaderMan
 				vk::AccessFlagBits::eDepthStencilAttachmentWrite | vk::AccessFlagBits::eColorAttachmentWrite,
 				vk::AccessFlagBits::eDepthStencilAttachmentRead | vk::AccessFlagBits::eDepthStencilAttachmentWrite
 					| vk::AccessFlagBits::eColorAttachmentRead | vk::AccessFlagBits::eColorAttachmentWrite);
+		/* The picture is cleared and drawn into an image the frontend was
+		 * handed before, on the queue the two share: whatever read it there -
+		 * a shader, a compute upscaler, a copy - is done before this clears it,
+		 * or a GPU that draws in tiles shows tiles of the next frame with only
+		 * its opaque polygons drawn yet. */
+		dependencies.emplace_back(VK_SUBPASS_EXTERNAL, 0,
+				vk::PipelineStageFlagBits::eFragmentShader | vk::PipelineStageFlagBits::eComputeShader | vk::PipelineStageFlagBits::eTransfer,
+				vk::PipelineStageFlagBits::eColorAttachmentOutput, vk::AccessFlags(), vk::AccessFlagBits::eColorAttachmentWrite);
 		// the depth the frame leaves, for the motion vector pass and the upscaler
 		if (upscaled)
 			dependencies.emplace_back(0, VK_SUBPASS_EXTERNAL,

tools/rend/speckle_test.sh

@@ -16,6 +16,13 @@
 #        Direct3D 12 vertex shaders place it with the precise
 #        transformVertex(), the Direct3D 11 ones' position is precise
 #
+# 3. The screen's picture cleared and drawn into while the frontend still
+#    reads the one it was handed in that image before: the frontend shows
+#    tiles of the next frame with its translucent polygons not drawn yet.
+#    Checked in the sources: the raster renderer's screen render pass has a
+#    dependency into its first subpass from the fragment shader and the
+#    transfer stages, as the per-pixel and SSAA ones have.
+#
 # 2. The per-pixel renderers' translucent modifier volumes change the
 #    fragments in the lists from their shaders: one draw toggles a stencil
 #    bit, the draw that closes a volume reads and clears it. Nothing orders
@@ -118,6 +125,19 @@ closing $R/vulkan/oit/oit_drawer.cpp 'GetTrModifierVolumePipeline[(]mv_mode == 1
 closing $R/gl4/abuffer.cpp 'g_abuffer_tr_modvol_shaders[[]mv_mode == 1' "OpenGL 4"
 closing $R/dx12/oit/dx12_oitrenderer.cpp 'DX12_OF_MV_INCLUSION : DX12_OF_MV_EXCLUSION' "Direct3D 12"
 
+# ---- 3. the picture the frontend reads, in the sources ------------------
+# (the screen's render pass clears and draws into an image the frontend was
+# handed before, on the queue the two share: a dependency into its first
+# subpass from the stages that read it there, or the frontend shows the next
+# frame's tiles with only its opaque polygons drawn yet. The per-pixel and
+# SSAA render passes have the fragment shader in theirs.)
+awk '
+   /emplace_back\(VK_SUBPASS_EXTERNAL, 0,/ { on = 1; text = "" }
+   on { text = text $0 }
+   on && /\);/ { on = 0; if (text ~ /eFragmentShader/ && text ~ /eTransfer/ && text ~ /eColorAttachmentWrite/) found = 1 }
+   END { exit !found }' $R/vulkan/drawer.cpp \
+   || bad "$R/vulkan/drawer.cpp: the screen's render pass clears its picture with no dependency on the frontend's reading of it"
+
 if [ $# -lt 2 ]; then
    [ $fail = 0 ] && echo "speckle_test: PASS (the sources; give CONTENT STATE for the device runs)"
    exit $fail