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【問】

I‘m trying to make an NDK based OpenGL application. At some point in my code, I want to check the OpenGL version available on the device.

I‘m using the following code :

const char *version = (const char *) glGetString(GL_VERSION);

if (strstr(version, "OpenGL ES 2.")) {

// do something

} else {

__android_log_print(ANDROID_LOG_ERROR, "NativeGL", "Open GL 2 not available (%s)", version=;

}

THe problem is that the version string is always equals to?"OpenGL ES-CM 1.1".

I‘m testing on both a Moto G (Android 4.4.4) and Samsung Galaxy Nexus (Android 4.3), both of which are OpenGL ES 2.0 compliant (the moto G is also OpenGL ES 3.0 compliant).

I tried to force the?EGL_CONTEXT_CLIENT_VERSION?when I initialise my display, but then eglChooseConfig returns 0 configurations. And when I test the context client version value in the default configuration, it‘s always 0 :

const EGLint attrib_list[] = {

EGL_BLUE_SIZE, 8,

EGL_GREEN_SIZE, 8,

EGL_RED_SIZE, 8,

EGL_NONE

};

?

// get the number of configs matching the attrib_list

EGLint num_configs;

eglChooseConfig(display, attrib_list, NULL, 0, &num_configs);

LOG_D(TAG, " ? %d EGL configurations found", num_configs);

?

// find matching configurations

EGLConfig configs[num_configs];

EGLint client_version = 0, depth_size = 0, stencil_size = 0, surface_type = 0;

eglChooseConfig(display, requirements, configs, num_configs, &num_configs);

for(int i = 0; i < num_configs; ++i){

?

eglGetConfigAttrib(display, configs[i], EGL_CONTEXT_CLIENT_VERSION, &client_version);

?

?

LOG_D(TAG, " client version %d = 0x%08x", i, client_version);

?

}

?

// Update the window format from the configuration

EGLint format;

eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID, &format);

ANativeWindow_setBuffersGeometry(window, 0, 0, format);

?

// create the surface and context

EGLSurface surface = eglCreateWindowSurface(display, config, window, NULL);

EGLContext context = eglCreateContext(display, config, NULL, NULL);

I‘m linking against the Open GL ES 2.0 library : here‘s the excerpt from my?Android.mk

LOCAL_LDLIBS := -landroid -llog -lEGL -lGLESv2

?

【答】

What version you get from?glGetString(GL_VERSION)?depends on which library you‘ve linked the code against, either?libGLESv1_CM.so?or?libGLESv2.so. Similarly for all the other common GL functions. This means that in practice, you need to build two separate .so files for your GL ES 1 and 2 versions of your rendering, and only load the right one once you know which one of them you can use (or load the function pointers dynamically). (This apparently is different when having compatibility between GL ES 2 and 3, where you can check using?glGetString(GL_VERSION).)

You didn‘t say where you tried using?EGL_CONTEXT_CLIENT_VERSION?- it should be used in the parameter array to?eglCreateContext?(which you only call once you actually have chosen a config). The attribute array given to?eglChooseConfig?should have the pair?EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT?to get a suitable config.

?

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來自：https://stackoverflow.com/questions/25843368/glgetstringgl-version-returns-opengl-es-cm-1-1-but-my-phone-supports-opengl

glGetString(GL_VERSION) returns “OpenGL ES-CM 1.1” but my phone supports OpenGL 2