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////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Window.hpp>
#include <X11/Xlib.h>
#define GLAD_GL_IMPLEMENTATION
#include <gl.h>
#include <array>
#include <iostream>
#include <cmath>
#include <cstdlib>
////////////////////////////////////////////////////////////
/// Initialize OpenGL states into the specified view
///
/// \param Window Target window to initialize
///
/// \return True if operation was successful, false otherwise
///
////////////////////////////////////////////////////////////
[[nodiscard]] bool initialize(sf::Window& window)
{
// Activate the window
if (!window.setActive())
{
std::cerr << "Failed to set the window as active" << std::endl;
return false;
}
// Setup OpenGL states
// Set color and depth clear value
#ifdef SFML_OPENGL_ES
glClearDepthf(1.f);
#else
glClearDepth(1.f);
#endif
glClearColor(0.f, 0.5f, 0.5f, 0.f);
// Enable Z-buffer read and write
glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
// Setup a perspective projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
const float extent = std::tan(sf::degrees(45).asRadians());
#ifdef SFML_OPENGL_ES
glFrustumf(-extent, extent, -extent, extent, 1.0f, 500.0f);
#else
glFrustum(-extent, extent, -extent, extent, 1.0f, 500.0f);
#endif
// Enable position and texture coordinates vertex components
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
return true;
}
////////////////////////////////////////////////////////////
/// Draw the OpenGL scene (a rotating cube) into
/// the specified view
///
/// \param window Target window for rendering
/// \param elapsedTime Time elapsed since the last draw
///
/// \return True if operation was successful, false otherwise
///
////////////////////////////////////////////////////////////
[[nodiscard]] bool draw(sf::Window& window, float elapsedTime)
{
// Activate the window
if (!window.setActive())
{
std::cerr << "Failed to set the window as active" << std::endl;
return false;
}
// Clear color and depth buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Apply some transformations
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.f, 0.f, -200.f);
glRotatef(elapsedTime * 10.f, 1.f, 0.f, 0.f);
glRotatef(elapsedTime * 6.f, 0.f, 1.f, 0.f);
glRotatef(elapsedTime * 18.f, 0.f, 0.f, 1.f);
// Define a 3D cube (6 faces made of 2 triangles composed by 3 vertices)
// clang-format off
constexpr std::array<GLfloat, 216> cube =
{
// positions // colors
-50, -50, -50, 1, 1, 0,
-50, 50, -50, 1, 1, 0,
-50, -50, 50, 1, 1, 0,
-50, -50, 50, 1, 1, 0,
-50, 50, -50, 1, 1, 0,
-50, 50, 50, 1, 1, 0,
50, -50, -50, 1, 1, 0,
50, 50, -50, 1, 1, 0,
50, -50, 50, 1, 1, 0,
50, -50, 50, 1, 1, 0,
50, 50, -50, 1, 1, 0,
50, 50, 50, 1, 1, 0,
-50, -50, -50, 1, 0, 1,
50, -50, -50, 1, 0, 1,
-50, -50, 50, 1, 0, 1,
-50, -50, 50, 1, 0, 1,
50, -50, -50, 1, 0, 1,
50, -50, 50, 1, 0, 1,
-50, 50, -50, 1, 0, 1,
50, 50, -50, 1, 0, 1,
-50, 50, 50, 1, 0, 1,
-50, 50, 50, 1, 0, 1,
50, 50, -50, 1, 0, 1,
50, 50, 50, 1, 0, 1,
-50, -50, -50, 0, 1, 1,
50, -50, -50, 0, 1, 1,
-50, 50, -50, 0, 1, 1,
-50, 50, -50, 0, 1, 1,
50, -50, -50, 0, 1, 1,
50, 50, -50, 0, 1, 1,
-50, -50, 50, 0, 1, 1,
50, -50, 50, 0, 1, 1,
-50, 50, 50, 0, 1, 1,
-50, 50, 50, 0, 1, 1,
50, -50, 50, 0, 1, 1,
50, 50, 50, 0, 1, 1
};
// clang-format on
// Draw the cube
glVertexPointer(3, GL_FLOAT, 6 * sizeof(GLfloat), cube.data());
glColorPointer(3, GL_FLOAT, 6 * sizeof(GLfloat), cube.data() + 3);
glDrawArrays(GL_TRIANGLES, 0, 36);
return true;
}
////////////////////////////////////////////////////////////
/// Entry point of application
///
/// \return Error code
///
////////////////////////////////////////////////////////////
int main()
{
// Open a connection with the X server
Display* display = XOpenDisplay(nullptr);
if (!display)
return EXIT_FAILURE;
// Get the default screen
const int screen = DefaultScreen(display);
// Create the main window
XSetWindowAttributes attributes;
attributes.background_pixel = BlackPixel(display, screen);
attributes.event_mask = KeyPressMask;
const Window window = XCreateWindow(display,
RootWindow(display, screen),
0,
0,
650,
330,
0,
DefaultDepth(display, screen),
InputOutput,
DefaultVisual(display, screen),
CWBackPixel | CWEventMask,
&attributes);
if (!window)
return EXIT_FAILURE;
// Set the window's name
XStoreName(display, window, "SFML Window");
// Create the windows which will serve as containers for our SFML views
const Window view1 = XCreateWindow(display,
window,
10,
10,
310,
310,
0,
DefaultDepth(display, screen),
InputOutput,
DefaultVisual(display, screen),
0,
nullptr);
const Window view2 = XCreateWindow(display,
window,
330,
10,
310,
310,
0,
DefaultDepth(display, screen),
InputOutput,
DefaultVisual(display, screen),
0,
nullptr);
// Show our windows
XMapWindow(display, window);
XFlush(display);
// Create our SFML views
sf::Window sfmlView1(view1);
sf::Window sfmlView2(view2);
// Create a clock for measuring elapsed time
const sf::Clock clock;
// Load OpenGL or OpenGL ES entry points using glad
if (!sfmlView1.setActive())
{
std::cerr << "Failed to set view 1 as active" << std::endl;
return EXIT_FAILURE;
}
#ifdef SFML_OPENGL_ES
gladLoadGLES1(sf::Context::getFunction);
#else
gladLoadGL(sf::Context::getFunction);
#endif
// Initialize our views
if (!initialize(sfmlView1))
{
std::cerr << "Failed to initialize view 1" << std::endl;
return EXIT_FAILURE;
}
if (!initialize(sfmlView2))
{
std::cerr << "Failed to initialize view 2" << std::endl;
return EXIT_FAILURE;
}
// Start the event loop
bool running = true;
while (running)
{
while (XPending(display))
{
// Get the next pending event
XEvent event;
XNextEvent(display, &event);
// Process it
switch (event.type)
{
// Any key is pressed: quit
case KeyPress:
running = false;
break;
}
}
// Draw something into our views
if (!draw(sfmlView1, clock.getElapsedTime().asSeconds()))
{
std::cerr << "Failed to draw on view 1" << std::endl;
return EXIT_FAILURE;
}
if (!draw(sfmlView2, clock.getElapsedTime().asSeconds() * 0.3f))
{
std::cerr << "Failed to draw on view 2" << std::endl;
return EXIT_FAILURE;
}
// Display the views on screen
sfmlView1.display();
sfmlView2.display();
}
// Close our SFML views before destroying the underlying window
sfmlView1.close();
sfmlView2.close();
// Destroy the window
XDestroyWindow(display, window);
// Close the display
XCloseDisplay(display);
}
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