// GLFW3 sample. Hello GLFW
//
// request SOIL (Simple OpenGL Image Library)
// by mieki256
// Last updated: <2024/02/28 03:32:29 +0900>

#include <stdlib.h>
#include <stdio.h>
#include <GLFW/glfw3.h>
#include <SOIL/SOIL.h>

void error_callback(int error, const char *description)
{
  fprintf(stderr, "Error: %s\n", description);
}

static void key_callback(GLFWwindow *window, int key, int scancode, int action, int mods)
{
  if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
  {
    glfwSetWindowShouldClose(window, GLFW_TRUE);
  }
}

int main(void)
{
  GLFWwindow *window;
  GLuint tex_id;

  glfwSetErrorCallback(error_callback);

  if (!glfwInit())
  {
    // Initialization failed
    exit(EXIT_FAILURE);
  }

  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 1); // set OpenGL 1.1
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);

  // create window
  window = glfwCreateWindow(1280, 720, "Hello GLFW", NULL, NULL);
  if (!window)
  {
    // Window or OpenGL context creation failed
    glfwTerminate();
    exit(EXIT_FAILURE);
  }

  glfwSetKeyCallback(window, key_callback);

  glfwMakeContextCurrent(window);

  glfwSwapInterval(1);

  // load texture image file. use SOIL
  tex_id = SOIL_load_OGL_texture("logo.png", SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_POWER_OF_TWO);
  if (tex_id > 0)
  {
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, tex_id);
  }
  else
  {
    glDisable(GL_TEXTURE_2D);
  }

  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  glEnable(GL_BLEND);

  int scrw, scrh;
  glfwGetFramebufferSize(window, &scrw, &scrh);
  glViewport(0, 0, scrw, scrh);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  double a = (double)scrw / (double)scrh;
  glOrtho(-a, a, -1.0, 1.0, 1.0, -1.0);
  
  double angle = 0.0;

  // main loop
  while (!glfwWindowShouldClose(window))
  {
    angle += (45.0 / 60.0);

    glClearColor(0.1, 0.2, 0.4, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glRotatef(angle, 0, 0, 1);

    float w = 0.8;
    float h = 0.8;
    glColor4f(1.0, 1.0, 1.0, 1.0);
    glBegin(GL_QUADS);
    glTexCoord2f(0.0, 0.0);
    glVertex3f(-w, +h, -0.5);
    glTexCoord2f(1.0, 0.0);
    glVertex3f(+w, +h, -0.5);
    glTexCoord2f(1.0, 1.0);
    glVertex3f(+w, -h, -0.5);
    glTexCoord2f(0.0, 1.0);
    glVertex3f(-w, -h, -0.5);
    glEnd();

    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  glfwDestroyWindow(window);
  glfwTerminate();
  exit(EXIT_SUCCESS);
}