I use EGL with Xlib and OpenGL. While I was drawing straight on the window everything was fine. Now I'm trying to use pixmaps as EGL surface but OpenGL doesn't change it at all.
I clean the background with the blue color using OpenGL. Here's what I get instead:
Here's minimal example demonstaiting the problem(drawing this trash).
UPDATE: I added error checks and find out that eglCopyBuffers produces EGL_BAD_NATIVE_PIXMAP. Docs tell this can happen in two cases: if implementation doesn't support native pixmaps or if native pixmap argument is not valid. They both seem unlikely. If I can create pixmap surface without error I believe implementation supports native pixmaps. if I can draw on the pixmap using native methods like XFillRectangle I believe pixmap is valid.
UPDATE: I'm running this on a laptop with Ubuntu Gnome. It has two video cards: Intel HD Graphics 5500(driver=i915) and Nvidia GeForce 920m(driver=nvidia). Main lines from es2_info output(full version):
EGL_VERSION: 1.4
EGL_VENDOR: NVIDIA
EGL_CLIENT_APIS: OpenGL_ES OpenGL
GL_VERSION: OpenGL ES 3.2 NVIDIA 375.66
GL_RENDERER: GeForce 920M/PCIe/SSE2
Code:
// main.c
// cc main.c -lX11 -lEGL -lGL
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <GL/gl.h>
#include <EGL/egl.h>
#include <X11/Xlib.h>
void
die(const char * errstr, ...) {
va_list ap;
va_start(ap, errstr);
vfprintf(stderr, errstr, ap);
va_end(ap);
exit(1);
}
int main() {
Display * display = XOpenDisplay(NULL);
if (!display) die("Can't create xlib display.\n");
int screen = XDefaultScreen(display);
GC gc = XDefaultGC(display, screen);
Window root_window = XRootWindow(display, screen);
unsigned long black_pixel = XBlackPixel(display, screen);
unsigned long white_pixel = XWhitePixel(display, screen);
Window window = XCreateSimpleWindow(display, root_window, 0, 0, 640, 480,
0, black_pixel, white_pixel);
if (!window) die("Can't create window.\n");
int res = XSelectInput(display, window, ExposureMask);
if (!res) die("XSelectInput failed.\n");
Pixmap pixmap = XCreatePixmap(display, window, 400, 400, 24);
if (!pixmap) die("Can't create pixmap.\n");
EGLDisplay egldisplay = eglGetDisplay(display);
if (EGL_NO_DISPLAY == egldisplay) die("Can't cate egl display.\n");
res = eglInitialize(egldisplay, NULL, NULL);
if (!res) die("eglInitialize failed.\n");
EGLConfig config;
int num_configs;
static int attrib_list[] = {
EGL_RED_SIZE, 8,
EGL_GREEN_SIZE, 8,
EGL_BLUE_SIZE, 8,
EGL_ALPHA_SIZE, 0,
EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
EGL_SURFACE_TYPE, EGL_PIXMAP_BIT,
EGL_NONE
};
res = eglChooseConfig(egldisplay, attrib_list, &config, 1, &num_configs);
if (!res) die("eglChooseConfig failed.\n");
if (0 == num_configs) die("No appropriate egl config found.\n");
EGLSurface surface =
eglCreatePixmapSurface(egldisplay, config, pixmap, NULL);
if (EGL_NO_SURFACE == surface) die("Can't create egl pixmap surface.\n");
res = eglBindAPI(EGL_OPENGL_API);
if (!res) die("eglBindApi failed.\n");
EGLContext context =
eglCreateContext(egldisplay, config, EGL_NO_CONTEXT, NULL);
if (EGL_NO_CONTEXT == config) die("Can't create egl context.\n");
res = eglMakeCurrent(egldisplay, surface, surface, context);
if (!res) die("eglMakeCurrent failed.\n");
res = XMapWindow(display, window);
if (!res) die("XMapWindow failed.\n");
while (1) {
XEvent event;
res = XNextEvent(display, &event);
if (Expose != event.type) continue;
glClearColor(0, 0, 1, 1);
glClear(GL_COLOR_BUFFER_BIT);
glFinish();
res = eglWaitGL();
if (!res) die("eglWaitGL failed.\n");
res = XCopyArea(display, pixmap, window, gc, 0, 0, 400, 400, 0, 0);
if (!res) die("XCopyArea failed.\n");
}
}
