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Created September 28, 2012 11:08
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X11 EGL
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egl.cpp
/* Created by exoticorn ( http://talk.maemo.org/showthread.php?t=37356 )
* edited and commented by André Bergner [endboss]
*
* libraries needed: libx11-dev, libgles2-dev
*
* compile with: g++ -lX11 -lEGL -lGLESv2 egl-example.cpp
*/
#include <iostream>
using namespace std;
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <sys/time.h>
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h>
#include <GLES2/gl2.h>
#include <EGL/egl.h>
const char vertex_src [] =
" \
attribute vec4 position; \
varying mediump vec2 pos; \
uniform vec4 offset; \
\
void main() \
{ \
gl_Position = position + offset; \
pos = position.xy; \
} \
";
const char fragment_src [] =
" \
varying mediump vec2 pos; \
uniform mediump float phase; \
\
void main() \
{ \
gl_FragColor = vec4( 1., 0.9, 0.7, 1.0 ) * \
cos( 30.*sqrt(pos.x*pos.x + 1.5*pos.y*pos.y) \
+ atan(pos.y,pos.x) - phase ); \
} \
";
const char vertex_src2 [] =
" \
attribute vec4 position; \
attribute vec2 aTexCoord; \
varying mediump vec2 vTexCoord; \
void main() \
{ \
gl_Position = mat4(1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) * position; \
vTexCoord = aTexCoord; \
} \
";
const char fragment_src2 [] =
" \
uniform sampler2D uTexture; \
varying mediump vec2 vTexCoord; \
void main() \
{ \
gl_FragColor = texture2D(uTexture, vTexCoord); \
} \
";
void
print_shader_info_log (
GLuint shader // handle to the shader
)
{
GLint length = 0;
glGetShaderiv ( shader , GL_INFO_LOG_LENGTH , &length );
if ( length ) {
char* buffer = new char [ length ];
glGetShaderInfoLog ( shader , length , NULL , buffer );
cout << "shader info: " << buffer << flush;
delete [] buffer;
GLint success;
glGetShaderiv( shader, GL_COMPILE_STATUS, &success );
if ( success != GL_TRUE ) exit ( 1 );
}
}
void
print_prog_info_log (GLuint prog)
{
GLint length = 0;
GLchar buf[256];
glGetProgramInfoLog(prog, 256, &length, buf);
if ( length ) {
cout << "prog info: " << buf << flush;
}
}
GLuint
load_shader (
const char *shader_source,
GLenum type
)
{
GLuint shader = glCreateShader( type );
glShaderSource ( shader , 1 , &shader_source , NULL );
glCompileShader ( shader );
print_shader_info_log ( shader );
return shader;
}
Display *x_display;
Window win;
EGLDisplay egl_display;
EGLContext egl_context;
GLfloat
norm_x = 0.0,
norm_y = 0.0,
offset_x = 0.0,
offset_y = 0.0,
p1_pos_x = 0.0,
p1_pos_y = 0.0;
GLint
phase_loc,
offset_loc,
position_loc;
GLint position_loc2;
GLint aTexCoord;
EGLSurface egl_surface;
bool update_pos = false;
const float vertexArray[] = {
0.0, 0.5, 0.0,
-0.5, 0.0, 0.0,
0.0, -0.5, 0.0,
0.5, 0.0, 0.0,
0.0, 0.5, 0.0
};
const float vertexArray2[] = {
0.0, 0.0, 0.0,
0.5, 0.0, 0.0,
0.0, 0.5, 0.0,
0.5, 0.5, 0.0,
};
const float vertexArray3[] = {
0.0, 0.0,
1.0, 0.0,
0.0, 1.0,
1.0, 1.0
};
void render(GLuint shader1, GLuint shader2)
{
static float phase = 0;
static int donesetup = 0;
static XWindowAttributes gwa;
//// draw
if ( !donesetup ) {
XWindowAttributes gwa;
XGetWindowAttributes ( x_display , win , &gwa );
glViewport ( 0 , 0 , gwa.width , gwa.height );
glClearColor ( 0.08 , 0.06 , 0.07 , 1.); // background color
donesetup = 1;
}
glClear ( GL_COLOR_BUFFER_BIT );
glUseProgram ( shader1 );
glUniform1f ( phase_loc , phase ); // write the value of phase to the shaders phase
phase = fmodf ( phase + 0.5f , 2.f * 3.141f ); // and update the local variable
if ( update_pos ) { // if the position of the texture has changed due to user action
GLfloat old_offset_x = offset_x;
GLfloat old_offset_y = offset_y;
offset_x = norm_x - p1_pos_x;
offset_y = norm_y - p1_pos_y;
p1_pos_x = norm_x;
p1_pos_y = norm_y;
offset_x += old_offset_x;
offset_y += old_offset_y;
update_pos = false;
}
glUniform4f ( offset_loc , offset_x , offset_y , 0.0 , 0.0 );
glVertexAttribPointer ( position_loc, 3, GL_FLOAT, false, 0, vertexArray );
glEnableVertexAttribArray ( position_loc );
glDrawArrays ( GL_TRIANGLE_STRIP, 0, 5 );
GLuint texture;
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
//unsigned char* buf = (unsigned char*)malloc(800 * 480 * 3);
// glReadPixels(0, 0, // x, y
// 800, 480, // w, h
// GL_RGB,
// GL_UNSIGNED_BYTE,
// buf);
glTexImage2D(GL_TEXTURE_2D,
0, // level
GL_RGB,
800, 480, // w, h
0, // border
GL_RGB,
GL_UNSIGNED_BYTE,
0);
// free(buf);
glCopyTexSubImage2D(GL_TEXTURE_2D,
0, // level
0, 0, // offset
0, 0, // x, y
800, 480); // w, h
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glUseProgram ( shader2 );
glVertexAttribPointer ( position_loc2, 3, GL_FLOAT, false, 0, vertexArray2 );
glEnableVertexAttribArray ( position_loc2 );
glVertexAttribPointer ( aTexCoord, 2, GL_FLOAT, false, 0, vertexArray3 );
glEnableVertexAttribArray ( aTexCoord );
glDrawArrays ( GL_TRIANGLE_STRIP, 0, 4 );
glBindTexture(GL_TEXTURE_2D, 0);
eglSwapBuffers ( egl_display, egl_surface ); // get the rendered buffer to the screen
}
////////////////////////////////////////////////////////////////////////////////////////////
int main()
{
/////// the X11 part //////////////////////////////////////////////////////////////////
// in the first part the program opens a connection to the X11 window manager
//
x_display = XOpenDisplay ( NULL ); // open the standard display (the primary screen)
if ( x_display == NULL ) {
cerr << "cannot connect to X server" << endl;
return 1;
}
Window root = DefaultRootWindow( x_display ); // get the root window (usually the whole screen)
XSetWindowAttributes swa;
swa.event_mask = ExposureMask | PointerMotionMask | KeyPressMask;
win = XCreateWindow ( // create a window with the provided parameters
x_display, root,
0, 0, 800, 480, 0,
CopyFromParent, InputOutput,
CopyFromParent, CWEventMask,
&swa );
XSetWindowAttributes xattr;
Atom atom;
int one = 1;
xattr.override_redirect = False;
XChangeWindowAttributes ( x_display, win, CWOverrideRedirect, &xattr );
XWMHints hints;
hints.input = True;
hints.flags = InputHint;
XSetWMHints(x_display, win, &hints);
XMapWindow ( x_display , win ); // make the window visible on the screen
XStoreName ( x_display , win , "GL test" ); // give the window a name
/////// the egl part //////////////////////////////////////////////////////////////////
// egl provides an interface to connect the graphics related functionality of openGL ES
// with the windowing interface and functionality of the native operation system (X11
// in our case.
egl_display = eglGetDisplay( (EGLNativeDisplayType) x_display );
if ( egl_display == EGL_NO_DISPLAY ) {
cerr << "Got no EGL display." << endl;
return 1;
}
if ( !eglInitialize( egl_display, NULL, NULL ) ) {
cerr << "Unable to initialize EGL" << endl;
return 1;
}
EGLint attr[] = { // some attributes to set up our egl-interface
EGL_BUFFER_SIZE, 16,
EGL_RED_SIZE, 5,
EGL_GREEN_SIZE, 6,
EGL_BLUE_SIZE, 5,
EGL_RENDERABLE_TYPE,
EGL_OPENGL_ES2_BIT,
EGL_NONE
};
EGLConfig ecfg;
EGLint num_config;
if ( !eglChooseConfig( egl_display, attr, &ecfg, 1, &num_config ) ) {
cerr << "Failed to choose config (eglError: " << eglGetError() << ")" << endl;
return 1;
}
if ( num_config != 1 ) {
cerr << "Didn't get exactly one config, but " << num_config << endl;
return 1;
}
egl_surface = eglCreateWindowSurface ( egl_display, ecfg, win, NULL );
if ( egl_surface == EGL_NO_SURFACE ) {
cerr << "Unable to create EGL surface (eglError: " << eglGetError() << ")" << endl;
return 1;
}
//// egl-contexts collect all state descriptions needed required for operation
EGLint ctxattr[] = {
EGL_CONTEXT_CLIENT_VERSION, 2,
EGL_NONE
};
egl_context = eglCreateContext ( egl_display, ecfg, EGL_NO_CONTEXT, ctxattr );
if ( egl_context == EGL_NO_CONTEXT ) {
cerr << "Unable to create EGL context (eglError: " << eglGetError() << ")" << endl;
return 1;
}
//// associate the egl-context with the egl-surface
eglMakeCurrent( egl_display, egl_surface, egl_surface, egl_context );
/////// the openGL part ///////////////////////////////////////////////////////////////
GLuint vertexShader = load_shader ( vertex_src , GL_VERTEX_SHADER ); // load vertex shader
GLuint fragmentShader = load_shader ( fragment_src , GL_FRAGMENT_SHADER ); // load fragment shader
GLuint shaderProgram = glCreateProgram (); // create program object
glAttachShader ( shaderProgram, vertexShader ); // and attach both...
glAttachShader ( shaderProgram, fragmentShader ); // ... shaders to it
glLinkProgram ( shaderProgram ); // link the program
//// now get the locations (kind of handle) of the shaders variables
position_loc = glGetAttribLocation ( shaderProgram , "position" );
phase_loc = glGetUniformLocation ( shaderProgram , "phase" );
offset_loc = glGetUniformLocation ( shaderProgram , "offset" );
if ( position_loc < 0 || phase_loc < 0 || offset_loc < 0 ) {
cerr << "Unable to get uniform location" << endl;
return 1;
}
vertexShader = load_shader ( vertex_src2 , GL_VERTEX_SHADER ); // load vertex shader
fragmentShader = load_shader ( fragment_src2 , GL_FRAGMENT_SHADER ); // load fragment shader
GLuint shaderProgram2 = glCreateProgram (); // create program object
glAttachShader ( shaderProgram2, vertexShader ); // and attach both...
glAttachShader ( shaderProgram2, fragmentShader ); // ... shaders to it
glLinkProgram ( shaderProgram2 ); // link the program
print_prog_info_log( shaderProgram2 );
position_loc2 = glGetAttribLocation ( shaderProgram2 , "position" );
aTexCoord = glGetAttribLocation ( shaderProgram2 , "aTexCoord" );
if ( position_loc2 < 0 || aTexCoord < 0 ) {
cerr << "Unable to get uniform location" << endl;
return 1;
}
const float
window_width = 800.0,
window_height = 480.0;
//// this is needed for time measuring --> frames per second
struct timezone tz;
timeval t1, t2;
gettimeofday ( &t1 , &tz );
int num_frames = 0;
bool quit = false;
while ( !quit ) { // the main loop
while ( XPending ( x_display ) ) { // check for events from the x-server
XEvent xev;
XNextEvent( x_display, &xev );
if ( xev.type == MotionNotify ) { // if mouse has moved
// cout << "move to: << xev.xmotion.x << "," << xev.xmotion.y << endl;
GLfloat window_y = (window_height - xev.xmotion.y) - window_height / 2.0;
norm_y = window_y / (window_height / 2.0);
GLfloat window_x = xev.xmotion.x - window_width / 2.0;
norm_x = window_x / (window_width / 2.0);
update_pos = true;
}
if ( xev.type == KeyPress ) quit = true;
}
render(shaderProgram, shaderProgram2); // now we finally put something on the screen
if ( ++num_frames % 100 == 0 ) {
gettimeofday( &t2, &tz );
float dt = t2.tv_sec - t1.tv_sec + (t2.tv_usec - t1.tv_usec) * 1e-6;
cout << "fps: " << num_frames / dt << endl;
num_frames = 0;
t1 = t2;
}
// usleep( 1000*10 );
}
//// cleaning up...
eglDestroyContext ( egl_display, egl_context );
eglDestroySurface ( egl_display, egl_surface );
eglTerminate ( egl_display );
XDestroyWindow ( x_display, win );
XCloseDisplay ( x_display );
return 0;
}
Raw
Makefile
all: egl
egl: egl.cpp
g++ -lX11 -lEGL -lGLESv2 egl.cpp -o egl
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