The mesa git repository has some EGL demos in progs/egl and all of their demos uses a small library called eglut, a GLUT-like library for EGL. It only works for X11, but it seems quite easy to use.
Eglut location in the repository tree.
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Thanks a lot, I did "apt-get source es2gears" and found a few examples! Boy are they sophisticated, one has to do quite some X11 studying, EGL indeed doesn't save you from knowing quite a bit about the underlying system and its event system.Originally posted by bridgman View Post
For those interested, my Makefile:
And the source file itself (es2tri.c) which draws a triangle which you can rotate with the up/down arrow keys:PHP Code:CC=gcc
LIBS=-lX11 -lEGL -lGLESv2
app: es2tri.c
$(CC) -o $@ $< $(LIBS)
PHP Code:/**************************************************************************
*
* Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
* All Rights Reserved.
*
**************************************************************************/
/*
* Draw a triangle with X/EGL and OpenGL ES 2.x
*/
#define USE_FULL_GL 0
#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>
#if USE_FULL_GL
#include <GL/gl.h> /* use full OpenGL */
#else
#include <GLES2/gl2.h> /* use OpenGL ES 2.x */
#endif
#include <EGL/egl.h>
#define FLOAT_TO_FIXED(X) ((X) * 65535.0)
static GLfloat view_rotx = 0.0, view_roty = 0.0;
static GLint u_matrix = -1;
static GLint attr_pos = 0, attr_color = 1;
static void
make_z_rot_matrix(GLfloat angle, GLfloat *m)
{
float c = cos(angle * M_PI / 180.0);
float s = sin(angle * M_PI / 180.0);
int i;
for (i = 0; i < 16; i++)
m[i] = 0.0;
m[0] = m[5] = m[10] = m[15] = 1.0;
m[0] = c;
m[1] = s;
m[4] = -s;
m[5] = c;
}
static void
make_scale_matrix(GLfloat xs, GLfloat ys, GLfloat zs, GLfloat *m)
{
int i;
for (i = 0; i < 16; i++)
m[i] = 0.0;
m[0] = xs;
m[5] = ys;
m[10] = zs;
m[15] = 1.0;
}
static void
mul_matrix(GLfloat *prod, const GLfloat *a, const GLfloat *b)
{
#define A(row,col) a[(col<<2)+row]
#define B(row,col) b[(col<<2)+row]
#define P(row,col) p[(col<<2)+row]
GLfloat p[16];
GLint i;
for (i = 0; i < 4; i++) {
const GLfloat ai0=A(i,0), ai1=A(i,1), ai2=A(i,2), ai3=A(i,3);
P(i,0) = ai0 * B(0,0) + ai1 * B(1,0) + ai2 * B(2,0) + ai3 * B(3,0);
P(i,1) = ai0 * B(0,1) + ai1 * B(1,1) + ai2 * B(2,1) + ai3 * B(3,1);
P(i,2) = ai0 * B(0,2) + ai1 * B(1,2) + ai2 * B(2,2) + ai3 * B(3,2);
P(i,3) = ai0 * B(0,3) + ai1 * B(1,3) + ai2 * B(2,3) + ai3 * B(3,3);
}
memcpy(prod, p, sizeof(p));
#undef A
#undef B
#undef PROD
}
static void
draw(void)
{
static const GLfloat verts[3][2] = {
{ -1, -1 },
{ 1, -1 },
{ 0, 1 }
};
static const GLfloat colors[3][3] = {
{ 1, 0, 0 },
{ 0, 1, 0 },
{ 0, 0, 1 }
};
GLfloat mat[16], rot[16], scale[16];
/* Set modelview/projection matrix */
make_z_rot_matrix(view_rotx, rot);
make_scale_matrix(0.5, 0.5, 0.5, scale);
mul_matrix(mat, rot, scale);
glUniformMatrix4fv(u_matrix, 1, GL_FALSE, mat);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
{
glVertexAttribPointer(attr_pos, 2, GL_FLOAT, GL_FALSE, 0, verts);
glVertexAttribPointer(attr_color, 3, GL_FLOAT, GL_FALSE, 0, colors);
glEnableVertexAttribArray(attr_pos);
glEnableVertexAttribArray(attr_color);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(attr_pos);
glDisableVertexAttribArray(attr_color);
}
}
/* new window size or exposure */
static void
reshape(int width, int height)
{
glViewport(0, 0, (GLint) width, (GLint) height);
}
static void
create_shaders(void)
{
static const char *fragShaderText =
"varying vec4 v_color;\n"
"void main() {\n"
" gl_FragColor = v_color;\n"
"}\n";
static const char *vertShaderText =
"uniform mat4 modelviewProjection;\n"
"attribute vec4 pos;\n"
"attribute vec4 color;\n"
"varying vec4 v_color;\n"
"void main() {\n"
" gl_Position = modelviewProjection * pos;\n"
" v_color = color;\n"
"}\n";
GLuint fragShader, vertShader, program;
GLint stat;
fragShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragShader, 1, (const char **) &fragShaderText, NULL);
glCompileShader(fragShader);
glGetShaderiv(fragShader, GL_COMPILE_STATUS, &stat);
if (!stat) {
printf("Error: fragment shader did not compile!\n");
exit(1);
}
vertShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertShader, 1, (const char **) &vertShaderText, NULL);
glCompileShader(vertShader);
glGetShaderiv(vertShader, GL_COMPILE_STATUS, &stat);
if (!stat) {
printf("Error: vertex shader did not compile!\n");
exit(1);
}
program = glCreateProgram();
glAttachShader(program, fragShader);
glAttachShader(program, vertShader);
glLinkProgram(program);
glGetProgramiv(program, GL_LINK_STATUS, &stat);
if (!stat) {
char log[1000];
GLsizei len;
glGetProgramInfoLog(program, 1000, &len, log);
printf("Error: linking:\n%s\n", log);
exit(1);
}
glUseProgram(program);
if (1) {
/* test setting attrib locations */
glBindAttribLocation(program, attr_pos, "pos");
glBindAttribLocation(program, attr_color, "color");
glLinkProgram(program); /* needed to put attribs into effect */
}
else {
/* test automatic attrib locations */
attr_pos = glGetAttribLocation(program, "pos");
attr_color = glGetAttribLocation(program, "color");
}
u_matrix = glGetUniformLocation(program, "modelviewProjection");
printf("Uniform modelviewProjection at %d\n", u_matrix);
printf("Attrib pos at %d\n", attr_pos);
printf("Attrib color at %d\n", attr_color);
}
static void
init(void)
{
typedef void (*proc)();
#if 1 /* test code */
proc p = eglGetProcAddress("glMapBufferOES");
assert(p);
#endif
glClearColor(0.4, 0.4, 0.4, 0.0);
create_shaders();
}
/*
* Create an RGB, double-buffered X window.
* Return the window and context handles.
*/
static void
make_x_window(Display *x_dpy, EGLDisplay egl_dpy,
const char *name,
int x, int y, int width, int height,
Window *winRet,
EGLContext *ctxRet,
EGLSurface *surfRet)
{
static const EGLint attribs[] = {
EGL_RED_SIZE, 1,
EGL_GREEN_SIZE, 1,
EGL_BLUE_SIZE, 1,
EGL_DEPTH_SIZE, 1,
EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
EGL_NONE
};
static const EGLint ctx_attribs[] = {
EGL_CONTEXT_CLIENT_VERSION, 2,
EGL_NONE
};
int scrnum;
XSetWindowAttributes attr;
unsigned long mask;
Window root;
Window win;
XVisualInfo *visInfo, visTemplate;
int num_visuals;
EGLContext ctx;
EGLConfig config;
EGLint num_configs;
EGLint vid;
scrnum = DefaultScreen( x_dpy );
root = RootWindow( x_dpy, scrnum );
if (!eglChooseConfig( egl_dpy, attribs, &config, 1, &num_configs)) {
printf("Error: couldn't get an EGL visual config\n");
exit(1);
}
assert(config);
assert(num_configs > 0);
if (!eglGetConfigAttrib(egl_dpy, config, EGL_NATIVE_VISUAL_ID, &vid)) {
printf("Error: eglGetConfigAttrib() failed\n");
exit(1);
}
/* The X window visual must match the EGL config */
visTemplate.visualid = vid;
visInfo = XGetVisualInfo(x_dpy, VisualIDMask, &visTemplate, &num_visuals);
if (!visInfo) {
printf("Error: couldn't get X visual\n");
exit(1);
}
/* window attributes */
attr.background_pixel = 0;
attr.border_pixel = 0;
attr.colormap = XCreateColormap( x_dpy, root, visInfo->visual, AllocNone);
attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
win = XCreateWindow( x_dpy, root, 0, 0, width, height,
0, visInfo->depth, InputOutput,
visInfo->visual, mask, &attr );
/* set hints and properties */
{
XSizeHints sizehints;
sizehints.x = x;
sizehints.y = y;
sizehints.width = width;
sizehints.height = height;
sizehints.flags = USSize | USPosition;
XSetNormalHints(x_dpy, win, &sizehints);
XSetStandardProperties(x_dpy, win, name, name,
None, (char **)NULL, 0, &sizehints);
}
#if USE_FULL_GL /* XXX fix this when eglBindAPI() works */
eglBindAPI(EGL_OPENGL_API);
#else
eglBindAPI(EGL_OPENGL_ES_API);
#endif
ctx = eglCreateContext(egl_dpy, config, EGL_NO_CONTEXT, ctx_attribs );
if (!ctx) {
printf("Error: eglCreateContext failed\n");
exit(1);
}
/* test eglQueryContext() */
{
EGLint val;
eglQueryContext(egl_dpy, ctx, EGL_CONTEXT_CLIENT_VERSION, &val);
assert(val == 2);
}
*surfRet = eglCreateWindowSurface(egl_dpy, config, win, NULL);
if (!*surfRet) {
printf("Error: eglCreateWindowSurface failed\n");
exit(1);
}
/* sanity checks */
{
EGLint val;
eglQuerySurface(egl_dpy, *surfRet, EGL_WIDTH, &val);
assert(val == width);
eglQuerySurface(egl_dpy, *surfRet, EGL_HEIGHT, &val);
assert(val == height);
assert(eglGetConfigAttrib(egl_dpy, config, EGL_SURFACE_TYPE, &val));
assert(val & EGL_WINDOW_BIT);
}
XFree(visInfo);
*winRet = win;
*ctxRet = ctx;
}
static void
event_loop(Display *dpy, Window win,
EGLDisplay egl_dpy, EGLSurface egl_surf)
{
while (1) {
int redraw = 0;
XEvent event;
XNextEvent(dpy, &event);
switch (event.type) {
case Expose:
redraw = 1;
break;
case ConfigureNotify:
reshape(event.xconfigure.width, event.xconfigure.height);
break;
case KeyPress:
{
char buffer[10];
int r, code;
code = XLookupKeysym(&event.xkey, 0);
if (code == XK_Left) {
view_roty += 5.0;
}
else if (code == XK_Right) {
view_roty -= 5.0;
}
else if (code == XK_Up) {
view_rotx += 5.0;
}
else if (code == XK_Down) {
view_rotx -= 5.0;
}
else {
r = XLookupString(&event.xkey, buffer, sizeof(buffer),
NULL, NULL);
if (buffer[0] == 27) {
/* escape */
return;
}
}
}
redraw = 1;
break;
default:
; /*no-op*/
}
if (redraw) {
draw();
eglSwapBuffers(egl_dpy, egl_surf);
}
}
}
static void
usage(void)
{
printf("Usage:\n");
printf(" -display <displayname> set the display to run on\n");
printf(" -info display OpenGL renderer info\n");
}
int
main(int argc, char *argv[])
{
const int winWidth = 300, winHeight = 300;
Display *x_dpy;
Window win;
EGLSurface egl_surf;
EGLContext egl_ctx;
EGLDisplay egl_dpy;
char *dpyName = NULL;
GLboolean printInfo = GL_FALSE;
EGLint egl_major, egl_minor;
int i;
const char *s;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-display") == 0) {
dpyName = argv[i+1];
i++;
}
else if (strcmp(argv[i], "-info") == 0) {
printInfo = GL_TRUE;
}
else {
usage();
return -1;
}
}
x_dpy = XOpenDisplay(dpyName);
if (!x_dpy) {
printf("Error: couldn't open display %s\n",
dpyName ? dpyName : getenv("DISPLAY"));
return -1;
}
egl_dpy = eglGetDisplay(x_dpy);
if (!egl_dpy) {
printf("Error: eglGetDisplay() failed\n");
return -1;
}
if (!eglInitialize(egl_dpy, &egl_major, &egl_minor)) {
printf("Error: eglInitialize() failed\n");
return -1;
}
s = eglQueryString(egl_dpy, EGL_VERSION);
printf("EGL_VERSION = %s\n", s);
s = eglQueryString(egl_dpy, EGL_VENDOR);
printf("EGL_VENDOR = %s\n", s);
s = eglQueryString(egl_dpy, EGL_EXTENSIONS);
printf("EGL_EXTENSIONS = %s\n", s);
s = eglQueryString(egl_dpy, EGL_CLIENT_APIS);
printf("EGL_CLIENT_APIS = %s\n", s);
make_x_window(x_dpy, egl_dpy,
"OpenGL ES 2.x tri", 0, 0, winWidth, winHeight,
&win, &egl_ctx, &egl_surf);
XMapWindow(x_dpy, win);
if (!eglMakeCurrent(egl_dpy, egl_surf, egl_surf, egl_ctx)) {
printf("Error: eglMakeCurrent() failed\n");
return -1;
}
if (printInfo) {
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
printf("GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
}
init();
/* Set initial projection/viewing transformation.
* We can't be sure we'll get a ConfigureNotify event when the window
* first appears.
*/
reshape(winWidth, winHeight);
event_loop(x_dpy, win, egl_dpy, egl_surf);
eglDestroyContext(egl_dpy, egl_ctx);
eglDestroySurface(egl_dpy, egl_surf);
eglTerminate(egl_dpy);
XDestroyWindow(x_dpy, win);
XCloseDisplay(x_dpy);
return 0;
}
Leave a comment:
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IIRC Michel made some changes to es2gears so that it built two versions - one for X and one for "DRI without X" which should give some pretty good examples. I wasn't able to find the commit when I took a quick look but will poke around when I have time.Originally posted by cl333r View Post
In theory there are some default options which should make the resulting code pretty portable - once you start specifying windows etc... you start getting tied to a specific window system.Leave a comment:
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Any OpenGL ES 2.0 with EGL example on Mesa?
Hi,
Is there any source code example using EGL and ES 2.0 on top of the (any) open source Linux drivers?
I got an ES 2.0 book but it's hard to figure out how to bind EGL to X (if you know what I mean) to be able to run the examples from the book.
Leave a comment: