Add common CLI Args parser for the samples (#8819)

NEW_RELEASE_NOTES.md

@@ -7,3 +7,5 @@ We are chaning the way Vulkan buffers are handled. We need to switch over to a m
 appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).
 
 ## Release notes for next branch cut
+
+- samples: samples now have a CLI to select backend api

samples/CMakeLists.txt

@@ -216,6 +216,21 @@ endif()
 
 target_sources(gltf-demo-resources PRIVATE ${RESGEN_SOURCE})
 
+# ==================================================================================================
+# Common Sample Utilities
+# ==================================================================================================
+
+add_library(samples-common STATIC
+    common/arguments.cpp
+)
+
+target_include_directories(samples-common PRIVATE
+    ${ROOT_DIR}/third_party/getopt/include
+)
+target_link_libraries(samples-common filament)
+
+set_target_properties(samples-common PROPERTIES FOLDER Samples/Common)
+
 # ==================================================================================================
 # Compiler flags
 # ==================================================================================================
@@ -234,7 +249,7 @@ endif()
 function(add_demo NAME)
     include_directories(${GENERATION_ROOT})
     add_executable(${NAME} ${NAME}.cpp)
-    target_link_libraries(${NAME} PRIVATE sample-resources filamentapp)
+    target_link_libraries(${NAME} PRIVATE sample-resources filamentapp samples-common)
     target_compile_options(${NAME} PRIVATE ${COMPILER_FLAGS})
     set_target_properties(${NAME} PROPERTIES FOLDER Samples)
 

samples/animation.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -65,6 +67,7 @@ static constexpr uint16_t TRIANGLE_INDICES[3] = { 0, 1, 2 };
 int main(int argc, char** argv) {
     Config config;
     config.title = "animation";
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
 
     App app;
     auto setup = [&app](Engine* engine, View* view, Scene* scene) {

samples/common/arguments.cpp

@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <filament/Engine.h>
+
+#include <utils/Path.h>
+
+#include <getopt/getopt.h>
+
+#include <iostream>
+#include <string>
+
+namespace samples {
+
+std::string getBackendAPIArgumentsUsage() {
+    return "   --api, -a\n"
+           "       Specify the backend API: opengl, vulkan, metal, or webgpu\n\n";
+}
+
+static void printUsage(char* name) {
+    std::string exec_name(utils::Path(name).getName());
+    std::string usage("EXEC_NAME\n"
+                      "Usage:\n"
+                      "    EXEC_NAME [options]\n"
+                      "Options:\n"
+                      "   --help, -h\n"
+                      "       Prints this message\n\n"
+                      "API_USAGE");
+    const std::string from("EXEC_NAME");
+    for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
+        usage.replace(pos, from.length(), exec_name);
+    }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos;
+            pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), getBackendAPIArgumentsUsage());
+    }
+    std::cout << usage;
+}
+
+filament::Engine::Backend parseArgumentsForBackend(const std::string& backend) {
+    if (backend == "metal") {
+        return filament::Engine::Backend::METAL;
+    } else if (backend == "opengl") {
+        return filament::Engine::Backend::OPENGL;
+    } else if (backend == "vulkan") {
+        return filament::Engine::Backend::VULKAN;
+    } else if (backend == "webgpu") {
+        return filament::Engine::Backend::WEBGPU;
+    } else {
+        std::cerr << "Unrecognized target API. Must be 'opengl'|'vulkan'|'metal'|'webgpu'."
+                  << std::endl;
+        exit(1);
+    }
+}
+
+filament::Engine::Backend parseArgumentsForBackend(int argc, char* argv[]) {
+    // The first colon in OPTSTR turns on silent error reporting. This is important, as the
+    // arguments may also contain gtest parameters we don't know about.
+    static constexpr const char* OPTSTR = "ha:";
+    static const struct option OPTIONS[] = {
+        { "help", no_argument,       nullptr, 'h' },
+        { "api",  required_argument, nullptr, 'a' },
+        { nullptr, 0,                nullptr, 0 }
+    };
+    int opt;
+    int optionIndex = 0;
+
+    while ((opt = getopt_long(argc, argv, OPTSTR, OPTIONS, &optionIndex)) >= 0) {
+        std::string arg(optarg ? optarg : "");
+        switch (opt) {
+            default:
+            case 'h':
+                printUsage(argv[0]);
+                exit(0);
+            case 'a':
+                return parseArgumentsForBackend(arg);
+        }
+    }
+    // if no args were provided return DEFAULT
+    return filament::Engine::Backend::DEFAULT;
+}
+
+} // namespace samples

samples/common/arguments.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TNT_SAMPLES_ARGUMENTS_H
+#define TNT_SAMPLES_ARGUMENTS_H
+
+#include <filament/Engine.h>
+
+#include <string>
+
+namespace samples {
+    filament::Engine::Backend parseArgumentsForBackend(int argc, char* argv[]);
+    filament::Engine::Backend parseArgumentsForBackend(const std::string& backend);
+    std::string getBackendAPIArgumentsUsage();
+}
+#endif //TNT_SAMPLES_ARGUMENTS_H

samples/depthtesting.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -69,6 +71,7 @@ static constexpr uint16_t TRIANGLE_INDICES[3] = { 0, 1, 2 };
 int main(int argc, char** argv) {
     Config config;
     config.title = "depthtesting";
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
 
     App app;
     auto setup = [&app](Engine* engine, View* view, Scene* scene) {

samples/frame_generator.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <atomic>
 #include <fstream>
 #include <iomanip>
@@ -111,8 +113,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default) or vulkan\n\n"
+            "API_USAGE"
             "   --ibl=<path to cmgen IBL>, -i <path>\n"
             "       Applies an IBL generated by cmgen's deploy option\n\n"
             "   --scale=[number], -s [number]\n"
@@ -137,6 +138,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -166,13 +171,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'i':
                 config->iblDirectory = arg;

samples/gltf_instances.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filamentapp/Config.h>
 #include <filamentapp/FilamentApp.h>
 #include <filamentapp/IBL.h>
@@ -85,8 +87,7 @@ static void printUsage(char* name) {
         "Options:\n"
         "   --help, -h\n"
         "       Prints this message\n\n"
-        "   --api, -a\n"
-        "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+        "API_USAGE"
         "   --ibl=<path to cmgen IBL>, -i <path>\n"
         "       Override the built-in IBL\n\n"
         "   --num=<number of initial instances>, -n <num>\n"
@@ -100,6 +101,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -124,15 +129,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'm':
                 app->instanceToAnimate = atoi(arg.c_str());

samples/gltf_viewer.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filamentapp/Config.h>
 #include <filamentapp/FilamentApp.h>
 #include <filamentapp/IBL.h>
@@ -155,19 +157,7 @@ static void printUsage(char* name) {
         "Options:\n"
         "   --help, -h\n"
         "       Prints this message\n\n"
-        "   --api, -a\n"
-        "       Specify the backend API: "
-
-// Matches logic in filament/backend/src/PlatformFactory.cpp for Backend::DEFAULT
-#if defined(FILAMENT_IOS) || defined(__APPLE__)
-        "opengl, vulkan, or metal (default)"
-#elif defined(FILAMENT_DRIVER_SUPPORTS_VULKAN)
-        "opengl, vulkan (default), or metal"
-#else
-        "opengl (default), vulkan, or metal"
-#endif
-        "\n\n"
-
+        "API_USAGE"
         "   --feature-level=<1|2|3>, -f <1|2|3>\n"
         "       Specify the feature level to use. The default is the highest supported feature level.\n\n"
         "   --batch=<path to JSON file or 'default'>, -b\n"
@@ -211,6 +201,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -249,15 +243,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'f':
                 if (arg == "1") {

samples/heightfield.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
 #include <filament/LightManager.h>
@@ -106,13 +108,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("HEIGHTFIELD");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -133,16 +138,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/hellomorphing.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -96,13 +98,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SAMPLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -123,16 +128,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/hellopbr.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Engine.h>
 #include <filament/LightManager.h>
 #include <filament/Material.h>
@@ -63,14 +65,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl, vulkan, metal, or webgpu\n"
-            "       NOTE that webgpu is not yet functional (it is in development).\n"
+            "API_USAGE"
     );
     const std::string from("EXEC");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -91,19 +95,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else if (arg == "webgpu") {
-                    app->config.backend = Engine::Backend::WEBGPU;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be "
-                                 "'opengl'|'vulkan'|'metal'|'webgpu'.\n";
-                    exit(1);
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/helloskinning.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -72,13 +74,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SAMPLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -99,16 +104,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/helloskinningbuffer.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -99,13 +101,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SAMPLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -126,16 +131,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/helloskinningbuffer_morebones.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -91,13 +93,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SAMPLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -118,16 +123,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/hellostereo.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -86,8 +88,7 @@ static void printUsage(char* name) {
         "Options:\n"
         "   --help, -h\n"
         "       Prints this message\n\n"
-        "   --api, -a\n"
-        "       Specify the backend API: opengl (default), vulkan, or metal\n"
+        "API_USAGE"
         "   --eyes=<stereoscopic eyes>, -y <stereoscopic eyes>\n"
         "       Sets the number of stereoscopic eyes (default: 2) when stereoscopic rendering is\n"
         "       enabled.\n"
@@ -98,6 +99,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -120,16 +125,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                    exit(1);
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'y': {
                 int eyeCount = 0;

samples/hellotriangle.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -77,13 +79,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl, vulkan, metal, or webgpu\n"
+            "API_USAGE"
     );
     const std::string from("HELLOTRIANGLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -104,19 +109,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else if (arg == "webgpu") {
-                    app->config.backend = Engine::Backend::WEBGPU;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be "
-                                 "'opengl'|'vulkan'|'metal'|'webgpu'.\n";
-                    exit(1);
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/image_viewer.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filamentapp/Config.h>
 #include <filamentapp/FilamentApp.h>
 
@@ -94,8 +96,7 @@ static void printUsage(char* name) {
         "Options:\n"
         "   --help, -h\n"
         "       Prints this message\n\n"
-        "   --api, -a\n"
-        "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+        "API_USAGE"
         "   --camera=<camera mode>, -c <camera mode>\n"
         "       Set the camera mode: orbit (default) or flight\n"
         "       Flight mode uses the following controls:\n"
@@ -109,6 +110,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -130,15 +135,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'c':
                 if (arg == "flight") {

samples/lightbulb.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <iostream>
 #include <string>
 #include <map>
@@ -80,8 +82,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
             "   --ibl=<path>, -i <path>\n"
             "       Applies an IBL\n\n"
             "       path can either be a directory containing IBL data files generated by cmgen,\n"
@@ -101,6 +102,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -128,15 +133,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'i':
                 config->iblDirectory = arg;

samples/material_sandbox.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <iostream>
 #include <string>
 #include <map>
@@ -88,8 +90,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
             "   --ibl=<path>, -i <path>\n"
             "       Applies an IBL\n\n"
             "       path can either be a directory containing IBL data files generated by cmgen,\n"
@@ -117,6 +118,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -144,15 +149,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'c':
                 if (arg == "flight") {

samples/multiple_windows.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <SDL.h>
 
 #include <filament/Camera.h>
@@ -45,7 +47,7 @@
 using namespace filament;
 
 namespace {
-    static constexpr Engine::Backend kBackend = Engine::Backend::OPENGL;
+    Engine::Backend kBackend = Engine::Backend::NOOP;
     static constexpr int kWidth = 640;
     static constexpr int kHeight = 480;
     static constexpr double kFieldOfViewDeg = 60.0;
@@ -94,6 +96,7 @@ int main(int argc, char *argv[]) {
     // ---- initialize ----
     FILAMENT_CHECK_POSTCONDITION(SDL_Init(SDL_INIT_EVENTS) == 0) << "SDL_Init Failure";
 
+    kBackend = samples::parseArgumentsForBackend(argc, argv);
     std::vector<Window> windows = { Window(), Window() };
     uint32_t windowFlags = SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI
                            | SDL_WINDOW_RESIZABLE;

samples/point_sprites.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -189,6 +191,7 @@ void animate(App& app, Engine* engine, View* view, double now) {
 int main(int argc, char** argv) {
     Config config;
     config.title = "point_sprites";
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
 
     App app;
     FilamentApp::get().animate([&app](Engine* e, View* v, double now) { animate(app, e, v, now); });

samples/rendertarget.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -130,8 +132,7 @@ static void printUsage(char* name) {
         "Options:\n"
         "   --help, -h\n"
         "       Prints this message\n\n"
-        "   --api, -a\n"
-        "       Specify the backend API: opengl (default), vulkan, or metal\n"
+        "API_USAGE"
         "   --mode, -m\n"
         "       Specify the reflection mode: camera (default), or renderables\n\n"
     );
@@ -139,6 +140,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -160,16 +165,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                    exit(1);
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'm':
                 if (arg == "camera") {

samples/sample_cloth.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <iostream>
 #include <string>
 #include <map>
@@ -72,8 +74,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
             "   --ibl=<path to cmgen IBL>, -i <path>\n"
             "       Applies an IBL generated by cmgen's deploy option\n\n"
             "   --split-view, -v\n"
@@ -85,6 +86,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -108,15 +113,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'i':
                 config->iblDirectory = arg;

samples/sample_full_pbr.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filamentapp/Config.h>
 #include <filamentapp/FilamentApp.h>
 #include <filamentapp/MeshAssimp.h>
@@ -102,8 +104,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
             "   --ibl=<path to cmgen IBL>, -i <path>\n"
             "       Applies an IBL generated by cmgen's deploy option\n\n"
             "   --split-view, -v\n"
@@ -130,6 +131,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -156,15 +161,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'i':
                 config->iblDirectory = arg;

samples/sample_normal_map.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <iostream>
 #include <string>
 #include <map>
@@ -78,8 +80,7 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
             "   --ibl=<path to cmgen IBL>, -i <path>\n"
             "       Applies an IBL generated by cmgen's deploy option\n\n"
             "   --split-view, -v\n"
@@ -97,6 +98,10 @@ static void printUsage(char* name) {
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -123,15 +128,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'." << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
             case 'i':
                 config->iblDirectory = arg;

samples/shadowtest.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
 #include <filament/LightManager.h>
@@ -70,6 +72,7 @@ static const Config config {
 
 int main(int argc, char** argv) {
     App app;
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
 
     auto setup = [&app](Engine* engine, View* view, Scene* scene) {
         auto& tcm = engine->getTransformManager();

samples/skinningtest.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -143,13 +145,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SAMPLE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -170,16 +175,7 @@ static int handleCommandLineArgments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'."
-                              << std::endl;
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/strobecolor.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Engine.h>
 #include <filament/View.h>
 #include <filament/Scene.h>
@@ -29,6 +31,7 @@ using namespace filament;
 int main(int argc, char** argv) {
     Config config;
     config.title = "strobecolor";
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
     Skybox* skybox;
 
     auto setup = [&skybox](Engine* engine, View* view, Scene* scene) {

samples/suzanne.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Engine.h>
 #include <filament/IndirectLight.h>
 #include <filament/LightManager.h>
@@ -73,13 +75,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n"
+            "API_USAGE"
     );
     const std::string from("SHOWCASE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -100,15 +105,7 @@ static int handleCommandLineArguments(int argc, char* argv[], Config* config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config->backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config->backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config->backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                }
+                config->backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/texturedquad.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/Camera.h>
 #include <filament/Engine.h>
 #include <filament/IndexBuffer.h>
@@ -87,12 +89,15 @@ static void printUsage(char* name) {
                       "Options:\n"
                       "   --help, -h\n"
                       "       Prints this message\n\n"
-                      "   --api, -a\n"
-                      "       Specify the backend API: opengl, vulkan, metal, or webgpu\n");
+                      "API_USAGE");
     const std::string from("TEXTUREDQUAD");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -113,19 +118,7 @@ static int handleCommandLineArguments(int argc, char* argv[], Config& config) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    config.backend = Engine::Backend::METAL;
-                } else if (arg == "webgpu") {
-                    config.backend = Engine::Backend::WEBGPU;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be "
-                                 "'opengl'|'vulkan'|'metal'|'webgpu'.\n";
-                    exit(1);
-                }
+                config.backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }

samples/vbotest.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/IndexBuffer.h>
 #include <filament/Material.h>
 #include <filament/RenderableManager.h>
@@ -45,6 +47,7 @@ static constexpr uint16_t TRIANGLE_INDICES[] { 0, 1, 2 };
 int main(int argc, char** argv) {
     Config config;
     config.title = "vbotest";
+    config.backend = samples::parseArgumentsForBackend(argc, argv);
 
     // Aggregate positions and colors into a single buffer without interleaving.
     std::vector<uint8_t> vbo(sizeof(POSITIONS) + sizeof(COLORS));

samples/viewtest.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "common/arguments.h"
+
 #include <filament/IndexBuffer.h>
 #include <filament/RenderableManager.h>
 #include <filament/Scene.h>
@@ -55,13 +57,16 @@ static void printUsage(char* name) {
             "Options:\n"
             "   --help, -h\n"
             "       Prints this message\n\n"
-            "   --api, -a\n"
-            "       Specify the backend API: opengl (default), vulkan, or metal\n\n"
+            "API_USAGE"
     );
     const std::string from("SHOWCASE");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
         usage.replace(pos, from.length(), exec_name);
     }
+    const std::string apiUsage("API_USAGE");
+    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
+        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
+    }
     std::cout << usage;
 }
 
@@ -82,15 +87,7 @@ static int handleCommandLineArguments(int argc, char* argv[], App* app) {
                 printUsage(argv[0]);
                 exit(0);
             case 'a':
-                if (arg == "opengl") {
-                    app->config.backend = Engine::Backend::OPENGL;
-                } else if (arg == "vulkan") {
-                    app->config.backend = Engine::Backend::VULKAN;
-                } else if (arg == "metal") {
-                    app->config.backend = Engine::Backend::METAL;
-                } else {
-                    std::cerr << "Unrecognized backend. Must be 'opengl'|'vulkan'|'metal'.\n";
-                }
+                app->config.backend = samples::parseArgumentsForBackend(arg);
                 break;
         }
     }