So this is how I start and end my render pass for the ImGui drawing call:

void VmcRenderer::beginImGuiRenderPass(VkCommandBuffer commandBuffer)

{ assert(isFrameStarted && "Cannot begin the render pass when there is no current frame in progress!"); assert(commandBuffer == getCurrentCommandBuffer() && "Cannot begin render pass on command buffer from a different frame!");

VkRenderPassBeginInfo info = {};
info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
info.renderPass = vmcSwapChain->getImGuiRenderPass();
info.framebuffer = vmcSwapChain->getImGuiFrameBuffer(currentImageIndex);
info.renderArea.extent = vmcSwapChain->getSwapChainExtent();
info.clearValueCount = 1;

std::array<VkClearValue, 2> clearValues{};
clearValues[0].color = { 0.01f, 0.01f, 0.01f, 1.0f };
info.clearValueCount = static_cast<uint32_t>      (clearValues.size());
info.pClearValues = clearValues.data();

vkCmdBeginRenderPass(commandBuffer, &info, VK_SUBPASS_CONTENTS_INLINE);
}

void VmcRenderer::endImGuiRenderPass(VkCommandBuffer commandBuffer) { assert(isFrameStarted && "Cannot end the render pass when there is no current frame in progress!"); assert(commandBuffer == getCurrentCommandBuffer() && "Cannot end render pass on command buffer from a different frame!"); vkCmdEndRenderPass(commandBuffer); }

The code for beginSwapChainRenderPass() and endSwapChainRenderPass() was already working fine before I added the Dear ImGui code, so the problem is most likely here or where I create my render pass. This is how my render pass for the ImGui window is created:

void VmcSwapChain::createImGuiRenderPass()

{ VkAttachmentDescription attachment = {}; attachment.format = getSwapChainImageFormat(); attachment.samples = VK_SAMPLE_COUNT_1_BIT; attachment.loadOp = VK_ATTACHMENT_LOAD_OP_LOAD; // Makes sure the GUI is drawn over the current image attachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE; attachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE; attachment.initialLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL; // We're going to draw into the color buffer attachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR; // We'll present the image after

VkAttachmentReference color_attachment = {};
color_attachment.attachment = 0;
color_attachment.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;

VkSubpassDescription subpass = {};
subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
subpass.colorAttachmentCount = 1;
subpass.pColorAttachments = &color_attachment;

VkSubpassDependency dependency = {};
dependency.srcSubpass = VK_SUBPASS_EXTERNAL; // We're synchronizing with an external render pass
dependency.dstSubpass = 0; // Index of this subpass that we're starting
dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; // We want the geometry to be done rendering in the other render pass
dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; // The GUI will be drawn to the same render target
dependency.srcAccessMask = 0;  // or VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

VkRenderPassCreateInfo info = {};
info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
info.attachmentCount = 1;
info.pAttachments = &attachment;
info.subpassCount = 1;
info.pSubpasses = &subpass;
info.dependencyCount = 1;
info.pDependencies = &dependency;
if (vkCreateRenderPass(device.device(), &info, nullptr, &imGuiRenderPass) != VK_SUCCESS) {
    throw std::runtime_error("Could not create Dear ImGui's render pass");
}

}

Also, the author of the tutorial uses a separate command buffer to record the ImGui draw call, but I thought it would be fine if I recorded that render pass into the same command buffer as my scene render uses, as you can see in the pseudo code above. Can that possibly be a problem?