KlassischeKeplerKriege/game/opengl.cpp

#include "opengl.hpp"

#include <iostream>
#include <sys/time.h>
#include <unistd.h>

#define UNUSED(foo) (void)foo;

timespec diff(timespec start, timespec end) {
  timespec result;
  if ((end.tv_nsec - start.tv_nsec) < 0) {
    result.tv_sec = end.tv_sec - start.tv_sec - 1;
    result.tv_nsec = 1000000000 + end.tv_nsec - start.tv_nsec;
  } else {
    result.tv_sec = end.tv_sec - start.tv_sec;
    result.tv_nsec = end.tv_nsec - start.tv_nsec;
  }
  return result;
}

endofthejedi::GLWindow::GLWindow(unsigned int width, unsigned int height)
    : m_width(width), m_height(height) {
  m_display = XOpenDisplay(NULL);

  if (m_display == NULL) {
    throw std::runtime_error("XOpenDisplay NULL");
  }

  m_rootwnd = DefaultRootWindow(m_display);

  m_visualinfo = glXChooseVisual(m_display, 0, m_attributes);

  if (m_visualinfo == NULL) {
    throw std::runtime_error("glXChooseVisual NULL");
  }

  m_colormap =
      XCreateColormap(m_display, m_rootwnd, m_visualinfo->visual, AllocNone);

  m_swa.colormap = m_colormap;
  m_swa.event_mask = ExposureMask | KeyPressMask;

  m_window = XCreateWindow(
      m_display, m_rootwnd, 0, 0, width, height, 0, m_visualinfo->depth,
      InputOutput, m_visualinfo->visual, CWColormap | CWEventMask, &m_swa);

  m_atomWmDeleteWindow = XInternAtom(m_display, "WM_DELETE_WINDOW", False);
  XSetWMProtocols(m_display, m_window, &m_atomWmDeleteWindow, 1);

  XMapWindow(m_display, m_window);
  XStoreName(m_display, m_window, "NAME");

  m_glcontext = glXCreateContext(m_display, m_visualinfo, NULL, GL_TRUE);

  XSync(m_display, False);

  glXMakeCurrent(m_display, m_window, m_glcontext);

  std::cout << "GL Renderer: " << glGetString(GL_RENDERER) << "\n";
  std::cout << "GL Version: " << glGetString(GL_VERSION) << "\n";
  std::cout << "GLSL Version: " << glGetString(GL_SHADING_LANGUAGE_VERSION)
            << "\n";

  init();

  XClearWindow(m_display, m_window);
  XMapRaised(m_display, m_window);
}

endofthejedi::GLWindow::~GLWindow() {
  glXMakeCurrent(m_display, None, NULL);
  glXDestroyContext(m_display, m_glcontext);
  XFree(m_visualinfo);
  XDestroyWindow(m_display, m_window);
  XCloseDisplay(m_display);
}

void endofthejedi::GLWindow::handleevents() {
  if (XPending(m_display) > 0) {
    XEvent xev;
    XNextEvent(m_display, &xev);
    handle(xev);
  }
}

void endofthejedi::GLWindow::handle(XEvent event) {
  if (event.type == Expose) {
    XWindowAttributes attribs;
    XGetWindowAttributes(m_display, m_window, &attribs);
    m_width = attribs.width;
    m_height = attribs.height;
    resize();
  } else if (event.type == ClientMessage) {
    if (event.xclient.data.l[0] == m_atomWmDeleteWindow) {
      stop();
    }
  } else if (event.type == DestroyNotify) {
    stop();
  }
}

void endofthejedi::GLWindow::swap() { glXSwapBuffers(m_display, m_window); }

void endofthejedi::GLWindow::loop() {
  m_running = true;

  timespec prev;
  timespec current;
  clock_gettime(CLOCK_MONOTONIC_RAW, &prev);
  clock_gettime(CLOCK_MONOTONIC_RAW, &current);

  double delta = 0.0;
  double sleeptime = 0.0;

  while (m_running) {
    handleevents();
    render(delta);
    swap();

    if (m_maxfps > 0) {
      sleeptime = ((1000000000.0/m_maxfps) - delta) + sleeptime;
      if (sleeptime > 0.0) {
        usleep((unsigned int)(sleeptime/1000.0));
        sleeptime = sleeptime - (unsigned int)(sleeptime/1000.0);
      }
    }

    clock_gettime(CLOCK_MONOTONIC_RAW, &current);
    delta = diff(prev, current).tv_nsec;
    prev = current;
    if(delta > 0.0) {
      m_fps = (1000000000.0/delta);
      //std::cout << m_fps << "\n";
    }
  }
}

void endofthejedi::GLWindow::stop() { m_running = false; }

void endofthejedi::GLWindow::init() {}
void endofthejedi::GLWindow::render(double time) { UNUSED(time) }
void endofthejedi::GLWindow::resize() {}