KlassischeKeplerKriege/game/opengl.cpp

#include "opengl.hpp"

#include <iostream>
#include <sys/time.h>
#include <unistd.h>
#include "options.hpp"

#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);
            if (ISSET_FLAG(SHOW_FPS)) {
                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() {}