Examples: Vulkan: Update GPU selection to pick discrete GPU if availa…

…ble, or use first GPU otherwise. (#4012) Fixes examples failing on optimus laptops with integrated graphics not supporting Vulkan.
ocornut · Apr 7, 2021 · bcdc8bc · bcdc8bc
1 parent c283a1d
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Showing 3 changed files with 33 additions and 8 deletions.
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
@@ -65,6 +65,7 @@ Other Changes:
 - Backends: OpenGL3: Don't try to read GL_CLIP_ORIGIN unless we're OpenGL 4.5. (#3998, #2366, #2186) [@s7jones]
 - Examples: Add OpenGL ES 2.0 support to modern GL examples. (#2837, #3951) [@lethal-guitar, @hinxx]
 - Examples: Vulkan: Rebuild swapchain on VK_SUBOPTIMAL_KHR. (#3881)
+- Examples: Vulkan: Prefer using discrete GPU if there are more than one available. (#4012) [@rokups]
 - Examples: SDL2: Link with shell32.lib required by SDL2main.lib since SDL 2.0.12. [#3988]
 - Docs: Improvements to minor mistakes in documentation comments (#3923) [@ANF-Studios]
 

diff --git a/examples/example_glfw_vulkan/main.cpp b/examples/example_glfw_vulkan/main.cpp
@@ -122,10 +122,22 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus);
         check_vk_result(err);
 
-        // If a number >1 of GPUs got reported, you should find the best fit GPU for your purpose
-        // e.g. VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU if available, or with the greatest memory available, etc.
-        // for sake of simplicity we'll just take the first one, assuming it has a graphics queue family.
-        g_PhysicalDevice = gpus[0];
+        // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
+        // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
+        // dedicated GPUs) is out of scope of this sample.
+        int use_gpu = 0;
+        for (int i = 0; i < (int)gpu_count; i++)
+        {
+            VkPhysicalDeviceProperties properties;
+            vkGetPhysicalDeviceProperties(gpus[i], &properties);
+            if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
+            {
+                use_gpu = i;
+                break;
+            }
+        }
+
+        g_PhysicalDevice = gpus[use_gpu];
         free(gpus);
     }
 

diff --git a/examples/example_sdl_vulkan/main.cpp b/examples/example_sdl_vulkan/main.cpp
@@ -114,10 +114,22 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus);
         check_vk_result(err);
 
-        // If a number >1 of GPUs got reported, you should find the best fit GPU for your purpose
-        // e.g. VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU if available, or with the greatest memory available, etc.
-        // for sake of simplicity we'll just take the first one, assuming it has a graphics queue family.
-        g_PhysicalDevice = gpus[0];
+        // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
+        // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
+        // dedicated GPUs) is out of scope of this sample.
+        int use_gpu = 0;
+        for (int i = 0; i < (int)gpu_count; i++)
+        {
+            VkPhysicalDeviceProperties properties;
+            vkGetPhysicalDeviceProperties(gpus[i], &properties);
+            if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
+            {
+                use_gpu = i;
+                break;
+            }
+        }
+
+        g_PhysicalDevice = gpus[use_gpu];
         free(gpus);
     }