add example for sdlgpu3 support

backend_test/example_sdlgpu3_fetchcontent/main.c

@@ -0,0 +1,164 @@
+#include "SDL3/SDL_pixels.h"
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_gpu.h>
+
+#include <cimgui.h>
+#include <cimgui_impl.h>
+
+#define CHECK(x)                                                               \
+  do {                                                                         \
+    void *value = (void *)x;                                                   \
+    if (!value || (void *)value == NULL) {                                     \
+      fprintf(stderr, "SDL Error: %s", SDL_GetError());                        \
+      exit(1);                                                                 \
+    }                                                                          \
+  } while (0)
+
+#define SCREEN_WIDTH 800
+#define SCREEN_HEIGHT 600
+#define SCREEN_FPS 60
+#define SCREEN_TICKS_PER_FRAME 1000 / SCREEN_FPS
+
+int main() {
+  if (!SDL_Init(SDL_INIT_VIDEO)) {
+    fprintf(stderr, "Failed to init video! %s", SDL_GetError());
+    return 1;
+  };
+
+  SDL_Window *window = NULL;
+  window = SDL_CreateWindow("Dung", SCREEN_WIDTH, SCREEN_HEIGHT, 0);
+  assert(window);
+
+  SDL_GPUDevice *device =
+      SDL_CreateGPUDevice(SDL_GPU_SHADERFORMAT_MSL, true, NULL);
+  assert(device);
+
+  const char *device_driver = SDL_GetGPUDeviceDriver(device);
+  CHECK(device_driver);
+
+  CHECK(SDL_ClaimWindowForGPUDevice(device, window));
+
+  // setup imgui
+  igCreateContext(NULL);
+
+  // set docking
+  ImGuiIO *ioptr = igGetIO();
+  ioptr->ConfigFlags |=
+      ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
+  // ioptr->ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable
+  // Gamepad Controls
+#ifdef IMGUI_HAS_DOCK
+  ioptr->ConfigFlags |= ImGuiConfigFlags_DockingEnable; // Enable Docking
+  ioptr->ConfigFlags |=
+      ImGuiConfigFlags_ViewportsEnable; // Enable Multi-Viewport / Platform
+                                        // Windows
+#endif
+
+  assert(ImGui_ImplSDL3_InitForSDLGPU(window));
+  assert(ImGui_ImplSDLGPU3_Init(&(ImGui_ImplSDLGPU3_InitInfo){
+      .ColorTargetFormat = SDL_GetGPUSwapchainTextureFormat(device, window),
+      .Device = device,
+      .MSAASamples = SDL_GPU_SAMPLECOUNT_1,
+  }));
+
+  // finish loading data
+
+  bool running = true;
+  SDL_Event e;
+  uint64_t now = SDL_GetTicks();
+  uint64_t previous = now;
+  uint64_t last_frame_time = now;
+  const bool *keyboard_state = SDL_GetKeyboardState(NULL);
+  bool demo_window_open = true;
+
+  while (running) {
+    const uint64_t ts = now - previous;
+
+    while (SDL_PollEvent(&e)) {
+      ImGui_ImplSDL3_ProcessEvent(&e);
+      switch (e.type) {
+      case SDL_EVENT_KEY_DOWN: {
+        switch (e.key.scancode) {
+        case SDL_SCANCODE_GRAVE: {
+          demo_window_open = !demo_window_open;
+        } break;
+
+        case SDL_SCANCODE_ESCAPE: {
+          running = false;
+        } break;
+
+        default:
+          continue;
+        }
+      } break;
+      case SDL_EVENT_QUIT: {
+        running = false;
+      } break;
+      default:;
+      }
+    }
+
+    previous = now;
+    now = SDL_GetTicks();
+    if (now - last_frame_time >= SCREEN_TICKS_PER_FRAME) {
+      last_frame_time = now;
+
+      ImGui_ImplSDLGPU3_NewFrame();
+      ImGui_ImplSDL3_NewFrame();
+      igNewFrame();
+
+      if (demo_window_open) {
+        igShowDemoWindow(&demo_window_open);
+      }
+
+      igRender();
+
+      SDL_GPUCommandBuffer *cmdbuf = SDL_AcquireGPUCommandBuffer(device);
+      if (cmdbuf == NULL) {
+        fprintf(stderr, "ERROR: SDL_AcquireGPUCommandBuffer failed: %s\n",
+                SDL_GetError());
+        break;
+      }
+
+      SDL_GPUTexture *swapchain_texture;
+      if (!SDL_WaitAndAcquireGPUSwapchainTexture(
+              cmdbuf, window, &swapchain_texture, NULL, NULL)) {
+        fprintf(stderr,
+                "ERROR: SDL_WaitAndAcquireGPUSwapchainTexture failed: %s\n",
+                SDL_GetError());
+        break;
+      }
+
+      if (swapchain_texture == NULL) {
+        fprintf(stderr, "ERROR: swapchain_texture is NULL\n");
+        SDL_SubmitGPUCommandBuffer(cmdbuf);
+        break;
+      }
+
+      SDL_GPUColorTargetInfo color_target_info = {0};
+      color_target_info.texture = swapchain_texture;
+      color_target_info.clear_color = (SDL_FColor){0, 0, 0, 1};
+      color_target_info.load_op = SDL_GPU_LOADOP_CLEAR;
+      color_target_info.store_op = SDL_GPU_STOREOP_STORE;
+
+      ImDrawData *imgui_draw_data = igGetDrawData();
+      Imgui_ImplSDLGPU3_PrepareDrawData(imgui_draw_data, cmdbuf);
+
+      SDL_GPURenderPass *render_pass =
+          SDL_BeginGPURenderPass(cmdbuf, &color_target_info, 1, NULL);
+      CHECK(render_pass);
+
+      ImGui_ImplSDLGPU3_RenderDrawData(imgui_draw_data, cmdbuf, render_pass,
+                                       NULL);
+
+      SDL_EndGPURenderPass(render_pass);
+      CHECK(SDL_SubmitGPUCommandBuffer(cmdbuf));
+    }
+  }
+  return 0;
+}