Draw first triangle

src/main.cc

@@ -0,0 +1,213 @@
+// GLAD
+#include "glad/glad.h"
+
+// GLM
+#define GLM_ENABLE_EXPERIMENTAL
+#include "glm/ext/matrix_transform.hpp"
+#include "glm/ext/vector_float3.hpp"
+#include "glm/gtc/type_ptr.hpp"
+#include "glm/trigonometric.hpp"
+#include "glm/gtx/rotate_vector.hpp"
+#include "glm/gtx/string_cast.hpp"
+
+// SDL
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_stdinc.h>
+#include <SDL2/SDL_error.h>
+#include <SDL2/SDL_video.h>
+#include <SDL2/SDL_events.h>
+#include <SDL2/SDL_mouse.h>
+#include <SDL2/SDL_keycode.h>
+
+// STDLIB
+#include <cstdint>
+#include <cstdio>
+#include <cmath>
+#include <string>
+#include <vector>
+
+#define WINDOW_WIDTH       1280
+#define WINDOW_HEIGHT      720
+#define WINDOW_HALF_WIDTH  640
+#define WINDOW_HALF_HEIGHT 360
+
+enum exit_codes : int {
+  EXIT_CODE_SUCCESS,
+  EXIT_CODE_SDL_INIT_FAILED,
+  EXIT_CODE_WINDOW_CREATION_FAILED,
+  EXIT_CODE_OPENGL_CONTEXT_FAILED,
+  EXIT_CODE_GLAD_LOADER_FAILED,
+};
+
+std::string load_shader(const std::string &filepath);
+
+int main() {
+  if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
+    return EXIT_CODE_SDL_INIT_FAILED;
+  }
+
+  SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 24);
+  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
+  SDL_Window *window = SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+                                        WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
+  if (!window) {
+    return EXIT_CODE_WINDOW_CREATION_FAILED;
+  }
+
+  SDL_GLContext context = SDL_GL_CreateContext(window);
+  if (!context) {
+    return EXIT_CODE_OPENGL_CONTEXT_FAILED;
+  }
+
+  if (gladLoadGLLoader(SDL_GL_GetProcAddress) == 0) {
+    return EXIT_CODE_GLAD_LOADER_FAILED;
+  }
+
+  glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
+
+  std::vector<GLfloat> vertices = {
+    -0.5f, -0.5f, 0.0f, // position
+     1.0f,  0.0f, 0.0f, // colour
+     0.5f, -0.5f, 0.0f, // position
+     0.0f,  0.0f, 1.0f, // colour
+     0.0f,  0.5f, 0.0f, // position
+     0.0f,  1.0f, 0.0f, // colour
+  };
+
+  std::vector<GLuint> indices = {0, 1, 2};
+
+  GLuint vao = 0;
+  glGenVertexArrays(1, &vao);
+  glBindVertexArray(vao);
+
+  GLuint ebo = 0;
+  glGenBuffers(1, &ebo);
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
+  glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint), indices.data(), GL_STATIC_DRAW);
+
+  GLuint vbo = 0;
+  glGenBuffers(1, &vbo);
+  glBindBuffer(GL_ARRAY_BUFFER, vbo);
+  glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(GLfloat), vertices.data(), GL_STATIC_DRAW);
+
+  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (void *)0);
+  glEnableVertexAttribArray(0);
+  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (void *)(3 * sizeof(GLfloat)));
+  glEnableVertexAttribArray(1);
+
+  glBindVertexArray(0);
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glDisableVertexAttribArray(0);
+  glDisableVertexAttribArray(1);
+
+  std::string vs_shader = load_shader("shaders/vert.glsl");
+  const char *vs_source = vs_shader.c_str();
+  GLuint vs = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vs, 1, &vs_source, NULL);
+  glCompileShader(vs);
+  GLint vs_compiled;
+  glGetShaderiv(vs, GL_COMPILE_STATUS, &vs_compiled);
+  if (vs_compiled != GL_TRUE)
+  {
+      GLsizei log_length = 0;
+      GLchar message[1024];
+      glGetShaderInfoLog(vs, 1024, &log_length, message);
+      printf("Failed to compile vertex shader: %s\n", message);
+  }
+
+  std::string fs_shader = load_shader("shaders/frag.glsl");
+  const char *fs_source = fs_shader.c_str();
+  GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(fs, 1, &fs_source, NULL);
+  glCompileShader(fs);
+  GLint fs_compiled;
+  glGetShaderiv(fs, GL_COMPILE_STATUS, &fs_compiled);
+  if (fs_compiled != GL_TRUE)
+  {
+      GLsizei log_length = 0;
+      GLchar message[1024];
+      glGetShaderInfoLog(fs, 1024, &log_length, message);
+      printf("Failed to compile fragment shader: %s\n", message);
+  }
+
+  GLuint program = glCreateProgram();
+  glAttachShader(program, vs);
+  glAttachShader(program, fs);
+  glLinkProgram(program);
+  GLint program_linked;
+  glGetProgramiv(program, GL_LINK_STATUS, &program_linked);
+  if (program_linked != GL_TRUE)
+  {
+      GLsizei log_length = 0;
+      GLchar message[1024];
+      glGetProgramInfoLog(program, 1024, &log_length, message);
+      printf("Failed to link program: %s\n", message);
+  }
+
+  glDeleteShader(vs);
+  glDeleteShader(fs);
+
+  bool running = true;
+  SDL_Event event = {};
+  while (running) {
+    while (SDL_PollEvent(&event)) {
+      switch (event.type) {
+        case SDL_QUIT:
+          running = false;
+          break;
+        case SDL_KEYDOWN:
+          if (event.key.keysym.sym == SDLK_ESCAPE) {
+            running = false;
+          }
+          break;
+        case SDL_WINDOWEVENT:
+          if (event.window.event == SDL_WINDOWEVENT_RESIZED) {
+            SDL_Window *wnd = SDL_GetWindowFromID(event.window.windowID);
+            if (!wnd) {
+              continue;
+            }
+            int w, h;
+            SDL_GL_GetDrawableSize(wnd, &w, &h);
+            glViewport(0, 0, w, h);
+          }
+          break;
+      }
+    }
+
+    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    glUseProgram(program);
+    glBindVertexArray(vao);
+    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, NULL);
+
+    SDL_GL_SwapWindow(window);
+  }
+
+  SDL_GL_DeleteContext(context);
+  SDL_DestroyWindow(window);
+  SDL_Quit();
+
+  return EXIT_CODE_SUCCESS;
+}
+
+std::string load_shader(const std::string &filepath) {
+  FILE *fp = fopen(filepath.c_str(), "r");
+  if (!fp) {
+    return "";
+  }
+
+  std::string output = {};
+
+  char buf[1024] = {0};
+  while (fgets(buf, sizeof(buf), fp)) {
+    output += buf;
+  }
+
+  return output;
+}