vkcube: Fix Cube Squishing on Resize

Modified viewport creation in vkcube to keep the
aspect ratio square and centered.

This change prevents cube from squishing and warping
when the window is resized.

It now shrinks and grows.

Change-Id: Ie2b3c5747293dfed968af5d83b581ac74d81bb10

2 files changed, 37 insertions, 17 deletions

diff --git a/cube/cube.c b/cube/cube.c
index 5382cd0e..9cbc45e5 100644
--- a/cube/cube.c
+++ b/cube/cube.c
@@ -99,10 +99,10 @@ void DbgMsg(char *fmt, ...) {
 
 #elif defined __ANDROID__
 #include <android/log.h>
-#define ERR_EXIT(err_msg, err_class)                                    \
-    do {                                                                \
+#define ERR_EXIT(err_msg, err_class)                                           \
+    do {                                                                       \
         ((void)__android_log_print(ANDROID_LOG_INFO, "Vulkan Cube", err_msg)); \
-        exit(1);                                                        \
+        exit(1);                                                               \
     } while (0)
 #ifdef VARARGS_WORKS_ON_ANDROID
 void DbgMsg(const char *fmt, ...) {
@@ -112,8 +112,8 @@ void DbgMsg(const char *fmt, ...) {
     va_end(va);
 }
 #else  // VARARGS_WORKS_ON_ANDROID
-#define DbgMsg(fmt, ...)                                                           \
-    do {                                                                           \
+#define DbgMsg(fmt, ...)                                                                  \
+    do {                                                                                  \
         ((void)__android_log_print(ANDROID_LOG_INFO, "Vulkan Cube", fmt, ##__VA_ARGS__)); \
     } while (0)
 #endif  // VARARGS_WORKS_ON_ANDROID
@@ -529,22 +529,21 @@ VKAPI_ATTR VkBool32 VKAPI_CALL debug_messenger_callback(VkDebugUtilsMessageSever
 #ifdef _WIN32
 
     in_callback = true;
-    if (!demo->suppress_popups)
-        MessageBox(NULL, message, "Alert", MB_OK);
+    if (!demo->suppress_popups) MessageBox(NULL, message, "Alert", MB_OK);
     in_callback = false;
 
 #elif defined(ANDROID)
 
     if (messageSeverity & VK_DEBUG_UTILS_MESSAGE_SEVERITY_INFO_BIT_EXT) {
-        __android_log_print(ANDROID_LOG_INFO,  APP_SHORT_NAME, "%s", message);
+        __android_log_print(ANDROID_LOG_INFO, APP_SHORT_NAME, "%s", message);
     } else if (messageSeverity & VK_DEBUG_UTILS_MESSAGE_SEVERITY_WARNING_BIT_EXT) {
-        __android_log_print(ANDROID_LOG_WARN,  APP_SHORT_NAME, "%s", message);
+        __android_log_print(ANDROID_LOG_WARN, APP_SHORT_NAME, "%s", message);
     } else if (messageSeverity & VK_DEBUG_UTILS_MESSAGE_SEVERITY_ERROR_BIT_EXT) {
         __android_log_print(ANDROID_LOG_ERROR, APP_SHORT_NAME, "%s", message);
     } else if (messageSeverity & VK_DEBUG_UTILS_MESSAGE_SEVERITY_VERBOSE_BIT_EXT) {
         __android_log_print(ANDROID_LOG_VERBOSE, APP_SHORT_NAME, "%s", message);
     } else {
-        __android_log_print(ANDROID_LOG_INFO,  APP_SHORT_NAME, "%s", message);
+        __android_log_print(ANDROID_LOG_INFO, APP_SHORT_NAME, "%s", message);
     }
 
 #else
@@ -772,8 +771,16 @@ static void demo_draw_build_cmd(struct demo *demo, VkCommandBuffer cmd_buf) {
                             &demo->swapchain_image_resources[demo->current_buffer].descriptor_set, 0, NULL);
     VkViewport viewport;
     memset(&viewport, 0, sizeof(viewport));
-    viewport.height = (float)demo->height;
-    viewport.width = (float)demo->width;
+    float viewport_dimension;
+    if (demo->width < demo->height) {
+        viewport_dimension = (float)demo->width;
+        viewport.y = (demo->height - demo->width) / 2.0f;
+    } else {
+        viewport_dimension = (float)demo->height;
+        viewport.x = (demo->width - demo->height) / 2.0f;
+    }
+    viewport.height = viewport_dimension;
+    viewport.width = viewport_dimension;
     viewport.minDepth = (float)0.0f;
     viewport.maxDepth = (float)1.0f;
     vkCmdSetViewport(cmd_buf, 0, 1, &viewport);
@@ -3763,7 +3770,7 @@ static void demo_init(struct demo *demo, int argc, char **argv) {
     memset(demo, 0, sizeof(*demo));
     demo->presentMode = VK_PRESENT_MODE_FIFO_KHR;
     demo->frameCount = INT32_MAX;
-    
+
     for (int i = 1; i < argc; i++) {
         if (strcmp(argv[i], "--use_staging") == 0) {
             demo->use_staging_buffer = true;
@@ -3953,7 +3960,6 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR pCmdLine,
 
 #elif defined(VK_USE_PLATFORM_IOS_MVK) || defined(VK_USE_PLATFORM_MACOS_MVK)
 static void demo_main(struct demo *demo, void *view, int argc, const char *argv[]) {
-
     demo_init(demo, argc, (char **)argv);
     demo->window = view;
     demo_init_vk_swapchain(demo);
diff --git a/cube/cube.cpp b/cube/cube.cpp
index abe80a88..4af97856 100644
--- a/cube/cube.cpp
+++ b/cube/cube.cpp
@@ -850,9 +850,23 @@ void Demo::draw_build_cmd(vk::CommandBuffer commandBuffer) {
     commandBuffer.bindPipeline(vk::PipelineBindPoint::eGraphics, pipeline);
     commandBuffer.bindDescriptorSets(vk::PipelineBindPoint::eGraphics, pipeline_layout, 0, 1,
                                      &swapchain_image_resources[current_buffer].descriptor_set, 0, nullptr);
-
-    auto const viewport =
-        vk::Viewport().setWidth((float)width).setHeight((float)height).setMinDepth((float)0.0f).setMaxDepth((float)1.0f);
+    float viewport_dimension;
+    float viewport_x = 0.0f;
+    float viewport_y = 0.0f;
+    if (width < height) {
+        viewport_dimension = (float)width;
+        viewport_y = (height - width) / 2.0f;
+    } else {
+        viewport_dimension = (float)height;
+        viewport_x = (width - height) / 2.0f;
+    }
+    auto const viewport = vk::Viewport()
+                              .setX(viewport_x)
+                              .setY(viewport_y)
+                              .setWidth((float)viewport_dimension)
+                              .setHeight((float)viewport_dimension)
+                              .setMinDepth((float)0.0f)
+                              .setMaxDepth((float)1.0f);
     commandBuffer.setViewport(0, 1, &viewport);
 
     vk::Rect2D const scissor(vk::Offset2D(0, 0), vk::Extent2D(width, height));