opengl-playground/pog.cpp

#include <EGL/egl.h>
// #include <GL/glew.h>
#include "include/gl_utils.h"
#include <GL/glut.h>
#include <GLFW/glfw3.h>
// #include <GLES2/gl2.h>
#include "pog.h"
#include <iostream>
int main() {
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
  // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
  GLFWwindow *window;
  window = glfwCreateWindow(1920, 1080, "Test Window", NULL, NULL);
  if (window == NULL) {
    // error handling
    std::cout << "AH HECK INIT FAILED BRUV" << std::endl;
    return 1;
  }
  glViewport(0, 0, 1920, 1080);
  glfwMakeContextCurrent(window);
  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

  // glad: load all OpenGL function pointers
  // ---------------------------------------
  if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
    std::cout << "Failed to initialize GLAD" << std::endl;
    return -1;
  }
  if (!GLAD_GL_ARB_direct_state_access) {
    /* see
     * https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_direct_state_access.txt
     * https://www.khronos.org/opengl/wiki/Direct_State_Access. This is the way.
     */
    std::cout << "DSA not supported!" << std::endl;
    return -1;
  }

  // compiling the shaders
  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";
  unsigned int vertexShader;
  vertexShader = glCreateShader(GL_VERTEX_SHADER); // compile code

  glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
  glCompileShader(vertexShader);

  int success;
  char infoLog[512];
  glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);

  if (!success) {
    glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
    std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n"
              << infoLog << std::endl;
  } // check if compilation succesful
  const char *fragmentShaderSource =
      "#version 330 core\n"
      "layout (location = 0) in vec3 aPos;\n"
      "void main()\n"
      "{\n"
      " FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);"
      "}\0";

  unsigned int fragmentShader;
  fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
  glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
  glCompileShader(fragmentShader); // compile fragment shader

  glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
  if (!success) {
    glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
    std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n"
              << infoLog << std::endl;
  };

  unsigned int shaderProgram;
  shaderProgram = glCreateProgram(); // create shader program

  // attaching shaders to our program
  glAttachShader(shaderProgram, vertexShader);
  glAttachShader(shaderProgram, fragmentShader);
  glLinkProgram(shaderProgram);
  glValidateProgram(shaderProgram);

  glUseProgram(shaderProgram); // use it NOW

  // not needed anymore they're linked
  glDeleteShader(vertexShader);
  glDeleteShader(fragmentShader);

  // Vertex data
  float vertices[] = {-0.5f, -0.5f, 0.0f, 0.5f, -0.5f, 0.0f, 0.0f, 0.5f, 0.0f};

  unsigned int VBO, VAO;
  glGenBuffers(1, &VBO);
  // bind vertex object
  glGenVertexArrays(1, &VAO);
  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  // tell OpenGL's stupid existence how to interpret data
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
  glEnableVertexAttribArray(0);

  while (!glfwWindowShouldClose(window)) {
    // input
    // -----
    processInput(window);

    // render
    // ------
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // draw our first triangle
    glUseProgram(shaderProgram);
    glBindVertexArray(
        VAO); // seeing as we only have a single VAO there's no need to bind it
              // every time, but we'll do so to keep things a bit more organized
    glDrawArrays(GL_TRIANGLES, 0, 3);
    // glBindVertexArray(0); // no need to unbind it every time

    // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved
    // etc.)
    // -------------------------------------------------------------------------------
    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  // optional: de-allocate all resources once they've outlived their purpose:
  // ------------------------------------------------------------------------
  glDeleteVertexArrays(1, &VAO);
  glDeleteBuffers(1, &VBO);
  glDeleteProgram(shaderProgram);

  // glfw: terminate, clearing all previously allocated GLFW resources.
  // ------------------------------------------------------------------
  glfwTerminate();
  return 0;
}

void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
  glViewport(0, 0, width, height);
}
void processInput(GLFWwindow *window) {
  if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
    glfwSetWindowShouldClose(window, true);
}