Fix potential resource dependency problem. (SaschaWillems#1079)

Author: scottchou007

examples/computeraytracing/computeraytracing.cpp

@@ -562,7 +562,7 @@ class VulkanExample : public VulkanExampleBase
 		VK_CHECK_RESULT(vkAllocateCommandBuffers(device, &cmdBufAllocateInfo, &compute.commandBuffer));
 
 		// Fence for compute CB sync
-		VkFenceCreateInfo fenceCreateInfo = vks::initializers::fenceCreateInfo(VK_FENCE_CREATE_SIGNALED_BIT);
+		VkFenceCreateInfo fenceCreateInfo = vks::initializers::fenceCreateInfo();
 		VK_CHECK_RESULT(vkCreateFence(device, &fenceCreateInfo, nullptr, &compute.fence));
 
 		// Build a single command buffer containing the compute dispatch commands
@@ -604,15 +604,15 @@ class VulkanExample : public VulkanExampleBase
 	{
 		// Submit compute commands
 		// Use a fence to ensure that compute command buffer has finished executing before using it again
-		vkWaitForFences(device, 1, &compute.fence, VK_TRUE, UINT64_MAX);
-		vkResetFences(device, 1, &compute.fence);
-
 		VkSubmitInfo computeSubmitInfo = vks::initializers::submitInfo();
 		computeSubmitInfo.commandBufferCount = 1;
 		computeSubmitInfo.pCommandBuffers = &compute.commandBuffer;
 
 		VK_CHECK_RESULT(vkQueueSubmit(compute.queue, 1, &computeSubmitInfo, compute.fence));
 
+		vkWaitForFences(device, 1, &compute.fence, VK_TRUE, UINT64_MAX);
+		vkResetFences(device, 1, &compute.fence);
+
 		VulkanExampleBase::prepareFrame();
 
 		// Command buffer to be submitted to the queue