implementations/Crafter.Graphics-UI.cpp

@@ -182,15 +182,41 @@ void UIRenderer::Dispatch(GraphicsCommandBuffer cmd, const GraphicsComputeShader
                           const void* push, std::uint32_t pushBytes,
                           std::uint32_t gx, std::uint32_t gy, std::uint32_t gz) {
     if (!firstDispatchThisFrame_) {
-        VkMemoryBarrier mb {
-            .sType         = VK_STRUCTURE_TYPE_MEMORY_BARRIER,
+        // Every UI pass read-modify-writes the same swapchain storage image
+        // (later passes overdraw earlier ones), so each dispatch must observe
+        // the previous dispatch's writes. The only resource the hazard touches
+        // is that one image, so scope the dependency to its subresource with a
+        // VkImageMemoryBarrier rather than a queue-wide VkMemoryBarrier: same
+        // correctness, but only this image's shader caches are flushed —
+        // unrelated buffers/images are no longer invalidated. The image stays
+        // in VK_IMAGE_LAYOUT_GENERAL (bound as a storage image), so this is a
+        // pure memory dependency, no layout transition.
+        //
+        // The execution dependency is still COMPUTE->COMPUTE over the whole
+        // queue, so the passes do NOT overlap — this is a narrower cache flush
+        // only. Eliminating the barriers entirely requires fusing the passes
+        // into one dispatch (tracked in #47); do not attempt that here.
+        VkImageMemoryBarrier ib {
+            .sType               = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
             .srcAccessMask       = VK_ACCESS_SHADER_WRITE_BIT,
             .dstAccessMask       = VK_ACCESS_SHADER_READ_BIT | VK_ACCESS_SHADER_WRITE_BIT,
+            .oldLayout           = VK_IMAGE_LAYOUT_GENERAL,
+            .newLayout           = VK_IMAGE_LAYOUT_GENERAL,
+            .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+            .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+            .image               = window_->images[window_->currentBuffer],
+            .subresourceRange    = {
+                .aspectMask     = VK_IMAGE_ASPECT_COLOR_BIT,
+                .baseMipLevel   = 0,
+                .levelCount     = 1,
+                .baseArrayLayer = 0,
+                .layerCount     = 1,
+            },
         };
         vkCmdPipelineBarrier(cmd,
             VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT,
             VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT,
-            0, 1, &mb, 0, nullptr, 0, nullptr);
+            0, 0, nullptr, 0, nullptr, 1, &ib);
     }
     firstDispatchThisFrame_ = false;
     shader.Dispatch(cmd, push, pushBytes, gx, gy, gz);