From db30e4bf5ce9219d675eac941477b5ae7af9e6d2 Mon Sep 17 00:00:00 2001
From: Tony Barbour <tony@LunarG.com>
Date: Tue, 11 Oct 2016 11:41:05 -0600
Subject: demos: Cube barrier changes from GH #1033

Change-Id: Ic68f9cd722474dc74957625c23c0f801f4b3852c
---
 demos/cube.c | 43 +++++++++++--------------------------------
 1 file changed, 11 insertions(+), 32 deletions(-)

diff --git a/demos/cube.c b/demos/cube.c
index 5a23657d..9477adbd 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -655,25 +655,7 @@ static void demo_draw_build_cmd(struct demo *demo, VkCommandBuffer cmd_buf) {
 
     err = vkBeginCommandBuffer(cmd_buf, &cmd_buf_info);
     assert(!err);
-
-    VkImageMemoryBarrier image_memory_barrier = {
-        .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
-        .pNext = NULL,
-        .srcAccessMask = VK_ACCESS_MEMORY_READ_BIT,
-        .dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
-        .oldLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
-        .newLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL,
-        .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-        .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-        .image = demo->buffers[demo->current_buffer].image,
-        .subresourceRange = {VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1}};
-
-    vkCmdPipelineBarrier(cmd_buf, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
-                         VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, 0, 0,
-                         NULL, 0, NULL, 1, &image_memory_barrier);
-
     vkCmdBeginRenderPass(cmd_buf, &rp_begin, VK_SUBPASS_CONTENTS_INLINE);
-
     vkCmdBindPipeline(cmd_buf, VK_PIPELINE_BIND_POINT_GRAPHICS, demo->pipeline);
     vkCmdBindDescriptorSets(cmd_buf, VK_PIPELINE_BIND_POINT_GRAPHICS,
                             demo->pipeline_layout, 0, 1, &demo->desc_set, 0,
@@ -718,7 +700,7 @@ static void demo_draw_build_cmd(struct demo *demo, VkCommandBuffer cmd_buf) {
 
         vkCmdPipelineBarrier(cmd_buf,
                              VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
-                             VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, 0,
+                             VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0,
                              0, NULL, 0, NULL, 1, &image_ownership_barrier);
     }
     err = vkEndCommandBuffer(cmd_buf);
@@ -1077,12 +1059,6 @@ static void demo_prepare_buffers(struct demo *demo) {
                                 &demo->buffers[i].view);
         assert(!err);
 
-        // The draw loop will be expecting the presentable images to be in
-        // LAYOUT_PRESENT_SRC_KHR
-        // since that's how they're left at the end of every frame.
-        demo_set_image_layout(
-            demo, demo->buffers[i].image, VK_IMAGE_ASPECT_COLOR_BIT,
-            VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_PRESENT_SRC_KHR, 0);
     }
 
     if (NULL != presentModes) {
@@ -1153,11 +1129,6 @@ static void demo_prepare_depth(struct demo *demo) {
         vkBindImageMemory(demo->device, demo->depth.image, demo->depth.mem, 0);
     assert(!err);
 
-    demo_set_image_layout(demo, demo->depth.image, VK_IMAGE_ASPECT_DEPTH_BIT,
-                          VK_IMAGE_LAYOUT_UNDEFINED,
-                          VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
-                          0);
-
     /* create image view */
     view.image = demo->depth.image;
     err = vkCreateImageView(demo->device, &view, NULL, &demo->depth.view);
@@ -1579,6 +1550,14 @@ static void demo_prepare_descriptor_layout(struct demo *demo) {
 }
 
 static void demo_prepare_render_pass(struct demo *demo) {
+    // The initial layout for the color and depth attachments will be LAYOUT_UNDEFINED
+    // because at the start of the renderpass, we don't care about their contents.
+    // At the start of the subpass, the color attachment's layout will be transitioned
+    // to LAYOUT_COLOR_ATTACHMENT_OPTIMAL and the depth stencil attachment's layout
+    // will be transitioned to LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL.  At the end of
+    // the renderpass, the color attachment's layout will be transitioned to
+    // LAYOUT_PRESENT_SRC_KHR to be ready to present.  This is all done as part of
+    // the renderpass, no barriers are necessary.
     const VkAttachmentDescription attachments[2] = {
             [0] =
                 {
@@ -1588,7 +1567,7 @@ static void demo_prepare_render_pass(struct demo *demo) {
                  .storeOp = VK_ATTACHMENT_STORE_OP_STORE,
                  .stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
                  .stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
-                 .initialLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL,
+                 .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
                  .finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
                 },
             [1] =
@@ -1600,7 +1579,7 @@ static void demo_prepare_render_pass(struct demo *demo) {
                  .stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
                  .stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
                  .initialLayout =
-                     VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
+                     VK_IMAGE_LAYOUT_UNDEFINED,
                  .finalLayout =
                      VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
                 },
-- 
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