Implement basic ImGUI editor for a game

.gitignore

@@ -1,3 +1,5 @@
 .cache
 compile_commands.json
 main
+extern
+imgui.ini

compile

@@ -1,8 +1,8 @@
 #!/bin/bash
 
 CC=clang
-CFLAGS="-g -Wall $(pkg-config --cflags sdl2)"
-LIBS="$(pkg-config --libs sdl2)"
+CFLAGS="-g -Wall $(pkg-config --cflags sdl2) -Wl,-rpath,\$ORIGIN/lib -Ivendor"
+LIBS="$(pkg-config --libs sdl2) -Llib -lcimgui"
 SRC=src/*.c
 OUT=main
 

src/main.c

@@ -1,28 +1,77 @@
+#include "SDL_rect.h"
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_events.h>
 #include <SDL2/SDL_render.h>
 #include <SDL2/SDL_video.h>
+#include <stdint.h>
+#include <stdio.h>
+#define CIMGUI_DEFINE_ENUMS_AND_STRUCTS
+#include "cimgui/cimgui.h"
+#define CIMGUI_USE_SDL2
+#include "cimgui/cimgui_impl.h"
 #include <stdbool.h>
 
-#define WINDOW_WIDTH 800
-#define WINDOW_HEIGHT 600
+#define WINDOW_WIDTH 1280
+#define WINDOW_HEIGHT 720
+
+#define PLAYER_SIZE 50
+#define MIN_SPEED 10
+#define MAX_SPEED 3000
+
+static const float delta = 1.0f / 60.0f;
+
+typedef struct character Character;
+struct character {
+  SDL_FRect position;
+  ImVec4 color;
+  int direction;
+  float speed;
+};
+
+void update_character(Character *player);
+void render_character(SDL_Renderer *renderer, const Character *player);
+void toggle_direction(Character *player);
 
 int main(void) {
   SDL_Init(SDL_INIT_EVERYTHING);
 
-  SDL_Window *window =
-      SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
-                       WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_SHOWN);
+  SDL_Window *window = SDL_CreateWindow(
+      "Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH,
+      WINDOW_HEIGHT, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
 
   SDL_Renderer *renderer = SDL_CreateRenderer(
       window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
 
+  igCreateContext(NULL);
+  ImGuiIO *io = igGetIO();
+  // Enable Keyboard Controls
+  io->ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
+  // Enable Gamepad Controls
+  io->ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
+
+  igStyleColorsDark(NULL);
+  if (!ImGui_ImplSDL2_InitForSDLRenderer(window, renderer) ||
+      !ImGui_ImplSDLRenderer2_Init(renderer)) {
+    goto IMGUI_FAILED;
+  }
+
   bool running = true;
 
+  Character player = {
+      .position = {.x = WINDOW_WIDTH / 2.0f - PLAYER_SIZE / 2.0f,
+                   .y = 0.0f,
+                   .w = PLAYER_SIZE,
+                   .h = PLAYER_SIZE},
+      .direction = 1,
+      .speed = 10.0f,
+      .color = {.x = 0, .y = 0, .z = 0, .w = 255},
+  };
+
   SDL_Event event = {0};
 
   while (running) {
     while (SDL_PollEvent(&event)) {
+      ImGui_ImplSDL2_ProcessEvent(&event);
       switch (event.type) {
       case SDL_QUIT:
         running = false;
@@ -30,13 +79,43 @@ int main(void) {
       }
     }
 
+    update_character(&player);
+
+    ImGui_ImplSDLRenderer2_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    igNewFrame();
+
+    {
+      // Create a window and append into it.
+      igBegin("Player Properties", NULL, 0);
+
+      // Edit 1 float using a slider
+      igSliderFloat("Speed", &(player.speed), MIN_SPEED, MAX_SPEED, "%.6f", 0);
+
+      // Edit 3 floats representing a color
+      igColorEdit3("Color", (float *)&(player.color), 0);
+
+      igEnd();
+    }
+
+    igRender();
+
     SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
 
     SDL_RenderClear(renderer);
 
+    render_character(renderer, &player);
+
+    ImGui_ImplSDLRenderer2_RenderDrawData(igGetDrawData(), renderer);
+
     SDL_RenderPresent(renderer);
   }
 
+  ImGui_ImplSDLRenderer2_Shutdown();
+  ImGui_ImplSDL2_Shutdown();
+  igDestroyContext(NULL);
+
+IMGUI_FAILED:
   SDL_DestroyRenderer(renderer);
 
   SDL_DestroyWindow(window);
@@ -45,3 +124,28 @@ int main(void) {
 
   return 0;
 }
+
+void update_character(Character *player) {
+  player->position.y += player->speed * player->direction * delta;
+
+  if (player->position.y < 0 ||
+      player->position.y + player->position.h > WINDOW_HEIGHT) {
+    toggle_direction(player);
+
+    if (player->position.y < 0) {
+      player->position.y = 0;
+    } else {
+      player->position.y = WINDOW_HEIGHT - player->position.h;
+    }
+  }
+}
+
+void render_character(SDL_Renderer *renderer, const Character *player) {
+  SDL_SetRenderDrawColor(renderer, (uint8_t)(player->color.x * 255),
+                         (uint8_t)(player->color.y * 255),
+                         (uint8_t)(player->color.z * 255),
+                         (uint8_t)(player->color.w * 255));
+  SDL_RenderFillRectF(renderer, &(player->position));
+}
+
+void toggle_direction(Character *player) { player->direction *= -1; }