Fix computeshader sample first frame being rendered with bogus UBOs (#…

…1125)

After this change, the sample's render() method would first update its UBO and then start drawing stuff so as to have valid frame output from frame 0, similarly to other samples.

examples/computeshader/computeshader.cpp

@@ -1,6 +1,6 @@
 /*
 * Vulkan Example - Compute shader image processing
-* 
+*
 * This sample uses a compute shader to apply different filters to an image
 *
 * Copyright (C) 2016-2023 by Sascha Willems - www.saschawillems.de
@@ -344,20 +344,20 @@ class VulkanExample : public VulkanExampleBase
 		// Create a semaphore for compute & graphics sync
 		VkSemaphoreCreateInfo semaphoreCreateInfo = vks::initializers::semaphoreCreateInfo();
 		VK_CHECK_RESULT(vkCreateSemaphore(device, &semaphoreCreateInfo, nullptr, &graphics.semaphore));
-	
+
 		// Signal the semaphore
 		VkSubmitInfo submitInfo = vks::initializers::submitInfo();
 		submitInfo.signalSemaphoreCount = 1;
 		submitInfo.pSignalSemaphores = &graphics.semaphore;
 		VK_CHECK_RESULT(vkQueueSubmit(queue, 1, &submitInfo, VK_NULL_HANDLE));
-		VK_CHECK_RESULT(vkQueueWaitIdle(queue));	
+		VK_CHECK_RESULT(vkQueueWaitIdle(queue));
 
 		// Setup descriptors
 
 		// The graphics pipeline uses two sets with two bindings
 		// One set for displaying the input image and one set for displaying the output image with the compute filter applied
 		// Binding 0: Vertex shader uniform buffer
-		// Binding 1: Sampled image (before/after compute filter is applied) 
+		// Binding 1: Sampled image (before/after compute filter is applied)
 
 		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings = {
 			vks::initializers::descriptorSetLayoutBinding(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, VK_SHADER_STAGE_VERTEX_BIT, 0),
@@ -562,9 +562,11 @@ class VulkanExample : public VulkanExampleBase
 	virtual void render()
 	{
 		if (!prepared)
+		{
 			return;
-		draw();
+		}
 		updateUniformBuffers();
+		draw();
 	}
 
 	virtual void OnUpdateUIOverlay(vks::UIOverlay *overlay)