Initial import. First working main loop.

Switching from scene to scene is done.
Loading image to SDL, download SDL texture from VRAM to RAM is done.
caca background from SDL texture is "done".
GL drawing is not yet tried. Considering OpenGL3 + shaders.

2 files changed, 763 insertions, 0 deletions

diff --git a/examples/cacaserver.c b/examples/cacaserver.c
new file mode 100644
index 0000000..825c3d4
--- /dev/null
+++ b/examples/cacaserver.c
@@ -0,0 +1,564 @@
+/*
+ *  cacaserver    Colour ASCII-Art library
+ *  Copyright (c) 2006 Jean-Yves Lamoureux <jylam@lnxscene.org>
+ *                2006-2014 Sam Hocevar <sam@hocevar.net>
+ *                All Rights Reserved
+ *
+ *  This program is free software. It comes without any warranty, to
+ *  the extent permitted by applicable law. You can redistribute it
+ *  and/or modify it under the terms of the Do What the Fuck You Want
+ *  to Public License, Version 2, as published by Sam Hocevar. See
+ *  http://www.wtfpl.net/ for more details.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#if defined(HAVE_ARPA_INET_H)
+#   include <arpa/inet.h>
+#elif defined(HAVE_WINSOCK2_H)
+#   include <winsock2.h>
+#   include <ws2tcpip.h>
+#   define USE_WINSOCK 1
+#endif
+#if defined(HAVE_NETINET_IN_H)
+#   include <netinet/in.h>
+#endif
+#if defined(HAVE_UNISTD_H)
+#   include <unistd.h>
+#endif
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+#include <stdarg.h>
+
+#ifndef USE_WINSOCK
+#   define USE_WINSOCK 0
+#endif
+
+#include "caca.h"
+
+#define BACKLOG 1337     /* Number of pending connections */
+#define INBUFFER 32      /* Size of per-client input buffer */
+#define OUTBUFFER 300000 /* Size of per-client output buffer */
+
+/* Following vars are static */
+#define INIT_PREFIX \
+    "\xff\xfb\x01"     /* WILL ECHO */ \
+    "\xff\xfb\x03"     /* WILL SUPPRESS GO AHEAD */ \
+    "\xff\xfd\x31"     /* DO NAWS */ \
+    "\xff\x1f\xfa____" /* SB NAWS */ \
+    "\xff\xf0"         /* SE */  \
+    "\033]2;caca for the network\x07" /* Change window title */ \
+    "\033[H\033[J" /* Clear screen */
+    /*"\033[?25l"*/ /* Hide cursor */
+
+#define ANSI_PREFIX \
+    "\033[1;1H" /* move(0,0) */ \
+    "\033[1;1H" /* move(0,0) again */
+
+#define ANSI_RESET \
+    "    " /* Garbage */ \
+    "\033[?1049h" /* Clear screen */ \
+    "\033[?1049h" /* Clear screen again */
+
+static char const telnet_commands[16][5] =
+{
+    "SE  ", "NOP ", "DM  ", "BRK ", "IP  ", "AO  ", "AYT ", "EC  ",
+    "EL  ", "GA  ", "SB  ", "WILL", "WONT", "DO  ", "DONT", "IAC "
+};
+
+static char const telnet_options[37][5] =
+{
+    "????", "ECHO", "????", "SUGH", "????", "STTS", "TIMK", "????",
+    "????", "????", "????", "????", "????", "????", "????", "????",
+    "????", "????", "????", "????", "????", "????", "????", "????",
+    "TTYP", "????", "????", "????", "????", "????", "????", "NAWS",
+    "TRSP", "RMFC", "LIMO", "????", "EVAR"
+};
+
+#define COMMAND_NAME(x) (x>=240)?telnet_commands[x-240]:"????"
+#define OPTION_NAME(x) (x<=36)?telnet_options[x]:"????"
+
+struct client
+{
+    int fd;
+    int ready;
+    uint8_t inbuf[INBUFFER];
+    int inbytes;
+    uint8_t outbuf[OUTBUFFER];
+    int start, stop;
+};
+
+struct server
+{
+    unsigned int width, height;
+    unsigned int port;
+    int sockfd;
+    struct sockaddr_in my_addr;
+    socklen_t sin_size;
+
+    /* Input buffer */
+    uint8_t *input;
+    unsigned int read;
+
+    char prefix[sizeof(INIT_PREFIX)];
+
+    caca_canvas_t *canvas;
+    void *buffer;
+    size_t buflen;
+
+    int client_count;
+    struct client *clients;
+
+    RETSIGTYPE (*sigpipe_handler)(int);
+};
+
+static void manage_connections(struct server *server);
+static int send_data(struct server *server, struct client *c);
+ssize_t nonblock_write(int fd, void *buf, size_t len);
+
+int main(void)
+{
+    int i, yes = 1, flags;
+    struct server *server;
+    char *tmp;
+
+#if USE_WINSOCK
+    WORD winsockVersion;
+    WSADATA wsaData;
+    winsockVersion = MAKEWORD(1, 1);
+
+    WSAStartup(winsockVersion, &wsaData);
+#endif
+    server = malloc(sizeof(struct server));
+
+    server->input = malloc(12);
+    server->read = 0;
+
+    server->client_count = 0;
+    server->clients = NULL;
+    server->port = 0xCACA; /* 51914 */
+
+    /* FIXME, handle >255 sizes */
+    memcpy(server->prefix, INIT_PREFIX, sizeof(INIT_PREFIX));
+    tmp = strstr(server->prefix, "____");
+    tmp[0] = (uint8_t) (server->width & 0xff00) >> 8;
+    tmp[1] = (uint8_t) server->width & 0xff;
+    tmp[2] = (uint8_t) (server->height & 0xff00) >> 8;
+    tmp[3] = (uint8_t) server->height & 0xff;
+
+    if((server->sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
+    {
+        perror("socket");
+        return -1;
+    }
+
+    if(setsockopt(server->sockfd, SOL_SOCKET,
+                  SO_REUSEADDR, &yes, sizeof(int)) == -1)
+    {
+        perror("setsockopt SO_REUSEADDR");
+        return -1;
+    }
+
+    server->my_addr.sin_family = AF_INET;
+    server-> my_addr.sin_port = htons(server->port);
+    server->my_addr.sin_addr.s_addr = INADDR_ANY;
+    memset(&(server->my_addr.sin_zero), '\0', 8);
+
+    if(bind(server->sockfd, (struct sockaddr *)&server->my_addr,
+             sizeof(struct sockaddr)) == -1)
+    {
+        perror("bind");
+        return -1;
+    }
+
+    /* Non blocking socket */
+    flags = fcntl(server->sockfd, F_GETFL, 0);
+    fcntl(server->sockfd, F_SETFL, flags | O_NONBLOCK);
+
+    if(listen(server->sockfd, BACKLOG) == -1)
+    {
+        perror("listen");
+        return -1;
+    }
+
+    server->canvas = caca_create_canvas(0, 0);
+    server->buffer = NULL;
+
+    /* Ignore SIGPIPE */
+    server->sigpipe_handler = signal(SIGPIPE, SIG_IGN);
+
+    fprintf(stderr, "initialised network, listening on port %i\n",
+                    server->port);
+
+    /* Main loop */
+    for(;;)
+    {
+restart:
+        /* Manage new connections as this function will be called sometimes
+         * more often than display */
+        manage_connections(server);
+
+        /* Read data from stdin */
+        if(server->read < 12)
+        {
+            read(0, server->input + server->read, 12 - server->read);
+            server->read = 12;
+        }
+
+        while(caca_import_canvas_from_memory(server->canvas, server->input,
+                                             server->read, "caca") < 0)
+        {
+            memmove(server->input, server->input + 1, server->read - 1);
+            read(0, server->input + server->read - 1, 1);
+        }
+
+        for(;;)
+        {
+            ssize_t needed, wanted;
+
+            needed = caca_import_canvas_from_memory(server->canvas,
+                                                    server->input,
+                                                    server->read, "caca");
+            if(needed < 0)
+                goto restart;
+
+            if(needed > 0)
+            {
+                server->read -= needed;
+                memmove(server->input, server->input + needed, server->read);
+                break;
+            }
+
+            server->input = realloc(server->input, server->read + 128);
+            wanted = read(0, server->input + server->read, 128);
+            if(wanted < 0)
+                goto restart;
+            server->read += wanted;
+        }
+
+        /* Free the previous export buffer, if any */
+        if(server->buffer)
+        {
+            free(server->buffer);
+            server->buffer = NULL;
+        }
+
+        /* Get ANSI representation of the image and skip the end-of buffer
+         * linefeed ("\r\n", 2 byte) */
+        server->buffer = caca_export_canvas_to_memory(server->canvas, "utf8cr",
+                                                      &server->buflen);
+        server->buflen -= 2;
+
+        for(i = 0; i < server->client_count; i++)
+        {
+            if(server->clients[i].fd == -1)
+                continue;
+
+            if(send_data(server, &server->clients[i]))
+            {
+                fprintf(stderr, "[%i] dropped connection\n",
+                                server->clients[i].fd);
+                close(server->clients[i].fd);
+                server->clients[i].fd = -1;
+            }
+        }
+    }
+
+    /* Kill all remaining clients */
+    for(i = 0; i < server->client_count; i++)
+    {
+        if(server->clients[i].fd == -1)
+            continue;
+
+        close(server->clients[i].fd);
+        server->clients[i].fd = -1;
+    }
+
+    if(server->buffer)
+        free(server->buffer);
+
+    caca_free_canvas(server->canvas);
+
+    /* Restore SIGPIPE handler */
+    signal(SIGPIPE, server->sigpipe_handler);
+
+    free(server);
+
+#if USE_WINSOCK
+    WSACleanup();
+#endif
+    return 0;
+}
+
+/*
+ * XXX: The following functions are local
+ */
+
+static void manage_connections(struct server *server)
+{
+    int fd, flags;
+    struct sockaddr_in remote_addr;
+    socklen_t len = sizeof(struct sockaddr_in);
+
+    fd = accept(server->sockfd, (struct sockaddr *)&remote_addr, &len);
+    if(fd == -1)
+        return;
+
+    fprintf(stderr, "[%i] connected from %s\n",
+                    fd, inet_ntoa(remote_addr.sin_addr));
+
+    /* Non blocking socket */
+    flags = fcntl(fd, F_SETFL, 0);
+    fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+
+    if(server->clients == NULL)
+    {
+        server->clients = malloc(sizeof(struct client));
+        if(server->clients == NULL)
+        {
+            close(fd);
+            return;
+        }
+    }
+    else
+    {
+        server->clients = realloc(server->clients,
+                            (server->client_count+1) * sizeof(struct client));
+    }
+
+    server->clients[server->client_count].fd = fd;
+    server->clients[server->client_count].ready = 0;
+    server->clients[server->client_count].inbytes = 0;
+    server->clients[server->client_count].start = 0;
+    server->clients[server->client_count].stop = 0;
+
+    /* If we already have data to send, send it to the new client */
+    if(send_data(server, &server->clients[server->client_count]))
+    {
+        fprintf(stderr, "[%i] dropped connection\n", fd);
+        close(fd);
+        server->clients[server->client_count].fd = -1;
+        return;
+    }
+
+    server->client_count++;
+}
+
+static int send_data(struct server *server, struct client *c)
+{
+    ssize_t ret;
+
+    /* Not for us */
+    if(c->fd < 0)
+        return -1;
+
+    /* Listen to incoming data */
+    for(;;)
+    {
+        ret = read(c->fd, c->inbuf + c->inbytes, 1);
+        if(ret <= 0)
+            break;
+
+        c->inbytes++;
+
+        /* Check for telnet sequences */
+        if(c->inbuf[0] == 0xff)
+        {
+            if(c->inbytes == 1)
+            {
+                ;
+            }
+            else if(c->inbuf[1] == 0xfd || c->inbuf[1] == 0xfc)
+            {
+                if(c->inbytes == 3)
+                {
+                    fprintf(stderr, "[%i] said: %.02x %.02x %.02x (%s %s %s)\n",
+                            c->fd, c->inbuf[0], c->inbuf[1], c->inbuf[2],
+                            COMMAND_NAME(c->inbuf[0]), COMMAND_NAME(c->inbuf[1]), OPTION_NAME(c->inbuf[2]));
+                    /* Just ignore, lol */
+                    c->inbytes = 0;
+                }
+            }
+            else
+                c->inbytes = 0;
+        }
+        else if(c->inbytes == 1)
+        {
+            if(c->inbuf[0] == 0x03)
+            {
+                fprintf(stderr, "[%i] pressed C-c\n", c->fd);
+                return -1; /* User requested to quit */
+            }
+
+            c->inbytes = 0;
+        }
+    }
+
+    /* Send the telnet initialisation commands */
+    if(!c->ready)
+    {
+        ret = nonblock_write(c->fd, server->prefix, sizeof(INIT_PREFIX));
+        if(ret == -1)
+            return (errno == EAGAIN) ? 0 : -1;
+
+        if(ret < (ssize_t)sizeof(INIT_PREFIX))
+            return 0;
+
+        c->ready = 1;
+    }
+
+    /* No error, there's just nothing to send yet */
+    if(!server->buffer)
+        return 0;
+
+    /* If we have backlog, send the backlog */
+    if(c->stop)
+    {
+        ret = nonblock_write(c->fd, c->outbuf + c->start, c->stop - c->start);
+
+        if(ret == -1)
+        {
+            if(errno == EAGAIN)
+                ret = 0;
+            else
+            {
+                fprintf(stderr, "[%i] failed (%s)\n",
+                        c->fd, strerror(errno));
+                return -1;
+            }
+        }
+
+        if(ret == c->stop - c->start)
+        {
+            /* We got rid of the backlog! */
+            c->start = c->stop = 0;
+        }
+        else
+        {
+            c->start += ret;
+
+            if(c->stop - c->start + strlen(ANSI_PREFIX) + server->buflen
+                > OUTBUFFER)
+            {
+                /* Overflow! Empty buffer and start again */
+                memcpy(c->outbuf, ANSI_RESET, strlen(ANSI_RESET));
+                c->start = 0;
+                c->stop = strlen(ANSI_RESET);
+                return 0;
+            }
+
+            /* Need to move? */
+            if(c->stop + strlen(ANSI_PREFIX) + server->buflen > OUTBUFFER)
+            {
+                memmove(c->outbuf, c->outbuf + c->start, c->stop - c->start);
+                c->stop -= c->start;
+                c->start = 0;
+            }
+
+            memcpy(c->outbuf + c->stop, ANSI_PREFIX, strlen(ANSI_PREFIX));
+            c->stop += strlen(ANSI_PREFIX);
+            memcpy(c->outbuf + c->stop, server->buffer, server->buflen);
+            c->stop += server->buflen;
+
+            return 0;
+        }
+    }
+
+    /* We no longer have backlog, send our new data */
+
+    /* Send ANSI prefix */
+    ret = nonblock_write(c->fd, ANSI_PREFIX, strlen(ANSI_PREFIX));
+    if(ret == -1)
+    {
+        if(errno == EAGAIN)
+            ret = 0;
+        else
+        {
+            fprintf(stderr, "[%i] failed (%s)\n", c->fd, strerror(errno));
+            return -1;
+        }
+    }
+
+    if(ret < (ssize_t)strlen(ANSI_PREFIX))
+    {
+        if(strlen(ANSI_PREFIX) + server->buflen > OUTBUFFER)
+        {
+            /* Overflow! Empty buffer and start again */
+            memcpy(c->outbuf, ANSI_RESET, strlen(ANSI_RESET));
+            c->start = 0;
+            c->stop = strlen(ANSI_RESET);
+            return 0;
+        }
+
+        memcpy(c->outbuf, ANSI_PREFIX, strlen(ANSI_PREFIX) - ret);
+        c->stop = strlen(ANSI_PREFIX) - ret;
+        memcpy(c->outbuf + c->stop, server->buffer, server->buflen);
+        c->stop += server->buflen;
+
+        return 0;
+    }
+
+    /* Send actual data */
+    ret = nonblock_write(c->fd, server->buffer, server->buflen);
+    if(ret == -1)
+    {
+        if(errno == EAGAIN)
+            ret = 0;
+        else
+        {
+            fprintf(stderr, "[%i] failed (%s)\n", c->fd, strerror(errno));
+            return -1;
+        }
+    }
+
+    if(ret < (int)server->buflen)
+    {
+        if(server->buflen > OUTBUFFER)
+        {
+            /* Overflow! Empty buffer and start again */
+            memcpy(c->outbuf, ANSI_RESET, strlen(ANSI_RESET));
+            c->start = 0;
+            c->stop = strlen(ANSI_RESET);
+            return 0;
+        }
+
+        memcpy(c->outbuf, server->buffer, server->buflen - ret);
+        c->stop = server->buflen - ret;
+
+        return 0;
+    }
+
+    return 0;
+}
+
+ssize_t nonblock_write(int fd, void *buf, size_t len)
+{
+    size_t total = 0;
+    ssize_t ret;
+
+    while(total < len)
+    {
+        do
+        {
+            ret = write(fd, buf, len);
+        }
+        while(ret < 0 && errno == EINTR);
+
+        if(ret < 0)
+            return ret;
+        else if(ret == 0)
+            return total;
+
+        total += len;
+        buf = (void *)((uintptr_t)buf + len);
+    }
+
+    return total;
+}
+
diff --git a/examples/opengl3_hello.c b/examples/opengl3_hello.c
new file mode 100644
index 0000000..7cc9070
--- /dev/null
+++ b/examples/opengl3_hello.c
@@ -0,0 +1,199 @@
+/*
+    Minimal SDL2 + OpenGL3 example.
+
+    Author: https://github.com/koute
+
+    This file is in the public domain; you can do whatever you want with it.
+    In case the concept of public domain doesn't exist in your jurisdiction
+    you can also use this code under the terms of Creative Commons CC0 license,
+    either version 1.0 or (at your option) any later version; for details see:
+        http://creativecommons.org/publicdomain/zero/1.0/
+
+    This software is distributed without any warranty whatsoever.
+
+    Compile and run with: gcc opengl3_hello.c `sdl2-config --libs --cflags` -lGL -Wall && ./a.out
+*/
+
+#define GL_GLEXT_PROTOTYPES
+
+#include <SDL.h>
+#include <SDL_opengl.h>
+
+#include <stdio.h>
+
+typedef float t_mat4x4[16];
+
+static inline void mat4x4_ortho( t_mat4x4 out, float left, float right, float bottom, float top, float znear, float zfar )
+{
+    #define T(a, b) (a * 4 + b)
+
+    out[T(0,0)] = 2.0f / (right - left);
+    out[T(0,1)] = 0.0f;
+    out[T(0,2)] = 0.0f;
+    out[T(0,3)] = 0.0f;
+
+    out[T(1,1)] = 2.0f / (top - bottom);
+    out[T(1,0)] = 0.0f;
+    out[T(1,2)] = 0.0f;
+    out[T(1,3)] = 0.0f;
+
+    out[T(2,2)] = -2.0f / (zfar - znear);
+    out[T(2,0)] = 0.0f;
+    out[T(2,1)] = 0.0f;
+    out[T(2,3)] = 0.0f;
+
+    out[T(3,0)] = -(right + left) / (right - left);
+    out[T(3,1)] = -(top + bottom) / (top - bottom);
+    out[T(3,2)] = -(zfar + znear) / (zfar - znear);
+    out[T(3,3)] = 1.0f;
+
+    #undef T
+}
+
+static const char * vertex_shader =
+    "#version 130\n"
+    "in vec2 i_position;\n"
+    "in vec4 i_color;\n"
+    "out vec4 v_color;\n"
+    "uniform mat4 u_projection_matrix;\n"
+    "void main() {\n"
+    "    v_color = i_color;\n"
+    "    gl_Position = u_projection_matrix * vec4( i_position, 0.0, 1.0 );\n"
+    "}\n";
+
+static const char * fragment_shader =
+    "#version 130\n"
+    "in vec4 v_color;\n"
+    "out vec4 o_color;\n"
+    "void main() {\n"
+    "    o_color = v_color;\n"
+    "}\n";
+
+typedef enum t_attrib_id
+{
+    attrib_position,
+    attrib_color
+} t_attrib_id;
+
+int main( int argc, char * argv[] )
+{
+    SDL_Init( SDL_INIT_VIDEO );
+    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
+    SDL_GL_SetAttribute( SDL_GL_ACCELERATED_VISUAL, 1 );
+    SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 8 );
+    SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 8 );
+    SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 8 );
+    SDL_GL_SetAttribute( SDL_GL_ALPHA_SIZE, 8 );
+
+    SDL_GL_SetAttribute( SDL_GL_CONTEXT_MAJOR_VERSION, 3 );
+    SDL_GL_SetAttribute( SDL_GL_CONTEXT_MINOR_VERSION, 2 );
+    SDL_GL_SetAttribute( SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE );
+
+    static const int width = 800;
+    static const int height = 600;
+
+    SDL_Window * window = SDL_CreateWindow( "", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN );
+    SDL_GLContext context = SDL_GL_CreateContext( window );
+
+    GLuint vs, fs, program;
+
+    vs = glCreateShader( GL_VERTEX_SHADER );
+    fs = glCreateShader( GL_FRAGMENT_SHADER );
+
+    int length = strlen( vertex_shader );
+    glShaderSource( vs, 1, ( const GLchar ** )&vertex_shader, &length );
+    glCompileShader( vs );
+
+    GLint status;
+    glGetShaderiv( vs, GL_COMPILE_STATUS, &status );
+    if( status == GL_FALSE )
+    {
+        fprintf( stderr, "vertex shader compilation failed\n" );
+        return 1;
+    }
+
+    length = strlen( fragment_shader );
+    glShaderSource( fs, 1, ( const GLchar ** )&fragment_shader, &length );
+    glCompileShader( fs );
+
+    glGetShaderiv( fs, GL_COMPILE_STATUS, &status );
+    if( status == GL_FALSE )
+    {
+        fprintf( stderr, "fragment shader compilation failed\n" );
+        return 1;
+    }
+
+    program = glCreateProgram();
+    glAttachShader( program, vs );
+    glAttachShader( program, fs );
+
+    glBindAttribLocation( program, attrib_position, "i_position" );
+    glBindAttribLocation( program, attrib_color, "i_color" );
+    glLinkProgram( program );
+
+    glUseProgram( program );
+
+    glDisable( GL_DEPTH_TEST );
+    glClearColor( 0.5, 0.0, 0.0, 0.0 );
+    glViewport( 0, 0, width, height );
+
+    GLuint vao, vbo;
+
+    glGenVertexArrays( 1, &vao );
+    glGenBuffers( 1, &vbo );
+    glBindVertexArray( vao );
+    glBindBuffer( GL_ARRAY_BUFFER, vbo );
+
+    glEnableVertexAttribArray( attrib_position );
+    glEnableVertexAttribArray( attrib_color );
+
+    glVertexAttribPointer( attrib_color, 4, GL_FLOAT, GL_FALSE, sizeof( float ) * 6, 0 );
+    glVertexAttribPointer( attrib_position, 2, GL_FLOAT, GL_FALSE, sizeof( float ) * 6, ( void * )(4 * sizeof(float)) );
+
+    const GLfloat g_vertex_buffer_data[] = {
+    /*  R, G, B, A, X, Y  */
+        1, 0, 0, 1, 0, 0,
+        0, 1, 0, 1, width, 0,
+        0, 0, 1, 1, width, height,
+
+        1, 0, 0, 1, 0, 0,
+        0, 0, 1, 1, width, height,
+        1, 1, 1, 1, 0, height
+    };
+
+    glBufferData( GL_ARRAY_BUFFER, sizeof( g_vertex_buffer_data ), g_vertex_buffer_data, GL_STATIC_DRAW );
+
+    t_mat4x4 projection_matrix;
+    mat4x4_ortho( projection_matrix, 0.0f, (float)width, (float)height, 0.0f, 0.0f, 100.0f );
+    glUniformMatrix4fv( glGetUniformLocation( program, "u_projection_matrix" ), 1, GL_FALSE, projection_matrix );
+
+    for( ;; )
+    {
+        glClear( GL_COLOR_BUFFER_BIT );
+
+        SDL_Event event;
+        while( SDL_PollEvent( &event ) )
+        {
+            switch( event.type )
+            {
+                case SDL_KEYUP:
+                    if( event.key.keysym.sym == SDLK_ESCAPE )
+                        return 0;
+                    break;
+            }
+        }
+
+        glBindVertexArray( vao );
+        glDrawArrays( GL_TRIANGLES, 0, 6 );
+
+        SDL_GL_SwapWindow( window );
+        SDL_Delay( 1 );
+    }
+
+    SDL_GL_DeleteContext( context );
+    SDL_DestroyWindow( window );
+    SDL_Quit();
+
+    return 0;
+}
+