gistfile1.cpp

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <thread>
#include <cmath>

#define GLSL(src) "#version 150 core\n" #src

const char* vertex = GLSL(
  in vec2 position;
  void main() {
    gl_Position = vec4(position, 0.0, 1.0);
  }
);

const char* fragment = GLSL(
  uniform vec3 triangleColor;
  out vec4 outColor;
  void main() {
    outColor = vec4(triangleColor, 1.0);
  }
);

int main() {
  glewExperimental = GL_TRUE;
  glfwInit();

  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

  glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

  GLFWwindow* window = glfwCreateWindow(1366, 768, "OpenGL", glfwGetPrimaryMonitor(), nullptr); // Fullscreen
  glfwMakeContextCurrent(window);

  GLenum err = glewInit();
  if (GLEW_OK != err) {
    fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
    return 1;
  }
  float verts[] = {
    0.0f, 0.5f,
    0.5f, -0.5f,
    -0.5f, -0.5f
  };

  GLuint vbo;
  glGenBuffers(1, &vbo);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);
  glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);

  GLuint vao;
  glGenVertexArrays(1, &vao);
  glBindVertexArray(vao);

  GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
  glShaderSource(vertexShader, 1, &vertex, NULL);
  glCompileShader(vertexShader);

  GLint status;
  glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);

  if (status != GL_TRUE) {
    char buffer[512];
    glGetShaderInfoLog(vertexShader, 512, NULL, buffer);
    printf(buffer);
  }

  GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
  glShaderSource(fragmentShader, 1, &fragment, NULL);
  glCompileShader(fragmentShader);

  glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &status);
  if (status != GL_TRUE) {
    char buffer[512];
    glGetShaderInfoLog(fragmentShader, 512, NULL, buffer);
    printf(buffer);
  }

  GLuint shaderProgram = glCreateProgram();
  glAttachShader(shaderProgram, vertexShader);
  glAttachShader(shaderProgram, fragmentShader);

  glBindFragDataLocation(shaderProgram, 0, "outColor");
  glLinkProgram(shaderProgram);
  glUseProgram(shaderProgram);

  GLint posAttrib = glGetAttribLocation(shaderProgram, "position");
  glEnableVertexAttribArray(posAttrib);
  glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);

  GLint uniColor = glGetUniformLocation(shaderProgram, "triangleColor");

  while (!glfwWindowShouldClose(window)) {
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
      glfwSetWindowShouldClose(window, GL_TRUE);
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    float time = glfwGetTime();
    glUniform3f(uniColor, sin(time * 3.1415 * 5) / 2 +.5, 0.0f, 0.0f);

    glDrawArrays(GL_TRIANGLES, 0, 3);

    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  glDeleteProgram(shaderProgram);
  glDeleteShader(fragmentShader);
  glDeleteShader(vertexShader);

  glDeleteBuffers(1, &vbo);

  glfwTerminate();
}