Commit of work up to day 11 of learnopengl.com.

01-hello-triangle/src/main.cpp

@@ -0,0 +1,188 @@
+#define _USE_MATH_DEFINES
+#include <math.h>
+#include "dbc.hpp"
+#include <print>
+#include <glad/glad.h>
+#include <GLFW/glfw3.h>
+#include <vector>
+#include <functional>
+
+void framebuffer_size_callback(GLFWwindow *window, int widht, int height);
+void processInput(GLFWwindow *window);
+
+const unsigned int SCR_WIDTH = 800;
+const unsigned int SCR_HEIGHT = 600;
+
+struct Config {
+  unsigned int shaderProgram = 0;
+  unsigned int VAO = 0;
+  unsigned int EBO = 0;
+};
+
+const char *vertexShaderSource = "#version 330 core\n"
+    "layout (location = 0) in vec3 aPos;\n"
+    "void main()\n"
+    "{\n"
+    "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
+    "}\0";
+
+const char *fragmentShaderSource = "#version 330 core\n"
+    "out vec4 FragColor;\n"
+    "void main()\n"
+    "{\n"
+    "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
+    "}\n\0";
+
+void init_glfw() {
+  glfwInit();
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+}
+
+void framebuffer_size_callback(GLFWwindow *, int width, int height) {
+  glViewport(0, 0, width, height);
+}
+
+GLFWwindow* create_window() {
+  GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
+  dbc::check(window != NULL, "failed to open window");
+
+  glfwMakeContextCurrent(window);
+
+  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+
+  auto good = gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
+  dbc::check(good, "failed to load GLAD");
+
+  return window;
+}
+
+void processInput(GLFWwindow *window) {
+  if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
+    glfwSetWindowShouldClose(window, true);
+  }
+}
+
+void check_status(const char* what, unsigned int shader, GLenum check_type) {
+  int success = 0;
+  char infoLog[512] = {0};
+
+  if(check_type == GL_LINK_STATUS) {
+    glGetProgramiv(shader, check_type, &success);
+  } else {
+    glGetShaderiv(shader, check_type, &success);
+  }
+
+  if(!success) {
+    glGetShaderInfoLog(shader, 512, NULL, infoLog);
+    std::println("ERROR: Shader {} compile failed: {}", what, infoLog);
+  }
+}
+
+Config setup() {
+  unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+  glCompileShader(vertexShader);
+  check_status("vertex shader", vertexShader, GL_COMPILE_STATUS);
+
+  unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+  glCompileShader(fragmentShader);
+  check_status("fragment shader", fragmentShader, GL_COMPILE_STATUS);
+
+  unsigned int shaderProgram = glCreateProgram();
+  glAttachShader(shaderProgram, vertexShader);
+  glAttachShader(shaderProgram, fragmentShader);
+  glLinkProgram(shaderProgram);
+  check_status("shader program", shaderProgram, GL_LINK_STATUS);
+
+  glDeleteShader(vertexShader);
+  glDeleteShader(fragmentShader);
+
+  float vertices[] = {
+       0.5f,  0.5f, 0.0f,  // top right
+       0.5f, -0.5f, 0.0f,  // bottom right
+      -0.5f, -0.5f, 0.0f,  // bottom left
+      -0.5f,  0.5f, 0.0f   // top left
+  };
+
+  unsigned int indices[] = {  // note that we start from 0!
+      0, 1, 3,  // first Triangle
+      1, 2, 3   // second Triangle
+  };
+
+  unsigned int VBO = 0;
+  unsigned int VAO = 0;
+  unsigned int EBO = 0;
+
+  glGenVertexArrays(1, &VAO);
+  glGenBuffers(1, &VBO);
+  glGenBuffers(1, &EBO);
+
+  glBindVertexArray(VAO);
+  glBindBuffer(GL_ARRAY_BUFFER, VBO);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+  glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+
+  // 0 in arg one matches the vertexShader, line 1, location=0
+  // this attaches the vertices to that location in the shader
+  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+  glEnableVertexAttribArray(0);
+
+  // unbinds the magic currently active buffer
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+  // remember: do NOT unbind the EBO while a VAO is active as the bound element buffer object IS stored in the VAO; keep the EBO bound.
+  //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+
+  glBindVertexArray(0);
+
+  // glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+
+  return {
+    .shaderProgram = shaderProgram,
+    .VAO = VAO,
+    .EBO = EBO};
+}
+
+void render(GLFWwindow* window, const Config& config) {
+  glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  glUseProgram(config.shaderProgram);
+  glBindVertexArray(config.VAO);
+
+  glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
+
+  glfwSwapBuffers(window);
+  glfwPollEvents();
+}
+
+void cleanup(Config& config) {
+  glDeleteVertexArrays(1, &config.VAO);
+  glDeleteBuffers(1, &config.VAO);
+  glDeleteBuffers(1, &config.EBO);
+  glDeleteProgram(config.shaderProgram);
+}
+
+int main() {
+  init_glfw();
+
+  auto window = create_window();
+
+  auto config = setup();
+
+  while(!glfwWindowShouldClose(window)) {
+    processInput(window);
+    render(window, config);
+  }
+
+  cleanup(config);
+
+  glfwTerminate();
+
+  return 0;
+}