Question

我正在尝试在Windows 7上使用（Google的）角度运行OpenGL ES 2.0，但无论我把它放在哪里，glGetError()都会无限返回GL_INVALID_OPERATION。我被告知在没有上下文的情况下会发生这种情况，但是我使用的EGL不会产生任何错误。

我在每个EGL语句之后放assert(eglGetError() == EGL_SUCCESS)只是为了检查，并且没有错误。

然而，无论我把它放在哪里，这都会挂起程序，甚至直接在eglMakeCurrent()之后：


while((err = glGetError()) != GL_NO_ERROR) {
    ...    
}

以下是我的EGL设置代码（window是HWND）：


    mainDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
    if(mainDisplay == EGL_NO_DISPLAY) {
        ...
    }
    if(eglInitialize(mainDisplay, NULL, NULL) != EGL_TRUE) {
        ...
    }
    eglBindAPI(EGL_OPENGL_ES_API);
    EGLConfig bestConfiguration;
    EGLint numConfigurationsAvailable;
    if(!eglChooseConfig(mainDisplay, openGLConfigurationAttributes, &bestConfiguration, 1, &numConfigurationsAvailable)) {
        ...
    }
    const EGLint surfaceBaseAttributes[] = { EGL_NONE };
    displaySurface = eglCreateWindowSurface(mainDisplay, bestConfiguration, window, surfaceBaseAttributes);
    if(displaySurface == EGL_NO_SURFACE) {
        ...
    }
    const EGLint contextBaseAttributes[] = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE };
    openGLContext = eglCreateContext(mainDisplay, bestConfiguration, EGL_NO_CONTEXT, contextBaseAttributes);
    if(openGLContext == EGL_NO_CONTEXT) {
        ...
    }
    if(eglMakeCurrent(mainDisplay, displaySurface, displaySurface, openGLContext) != EGL_TRUE) {
        ...
    }

Answer 1

毕竟，我发现问题是窗口和输入变量之间的分辨率不匹配，不知何故，EGL没有拿起，但GL知道存在问题。我仍然想知道它为什么会发生以及如何防止这些问题的发生。

为了确定这一点，我花了大量时间分析Google的示例代码，发现他们以极其不同的方式初始化EGL。如果它对某人有帮助，那么Google就会在Angle示例中初始化EGL：


PFNEGLGETPLATFORMDISPLAYEXTPROC eglGetPlatformDisplayEXT = reinterpret_cast(eglGetProcAddress("eglGetPlatformDisplayEXT"));
if(!eglGetPlatformDisplayEXT) {
    ...
}
const EGLint displayAttributes[] = {
    EGL_PLATFORM_ANGLE_TYPE_ANGLE, EGL_PLATFORM_ANGLE_TYPE_DEFAULT_ANGLE,
    EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, EGL_DONT_CARE,
    EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, EGL_DONT_CARE,
    EGL_NONE
};
mainWindowDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, display, &displayAttributes[0]);
if(mainWindowDisplay == EGL_NO_DISPLAY) {
    ...
}

EGLint majorVersion, minorVersion;
if(eglInitialize(mainWindowDisplay, &majorVersion, &minorVersion) == EGL_FALSE) {
    ...
}

const char *displayExtensions = eglQueryString(mainWindowDisplay, EGL_EXTENSIONS);
bool hasKHRCreateContext = strstr(displayExtensions, "EGL_KHR_create_context") != nullptr;
if((majorVersion != 2 || minorVersion != 0) && !hasKHRCreateContext) {
    ...
}

eglBindAPI(EGL_OPENGL_ES_API);
if(eglGetError() != EGL_SUCCESS) {
    ...
}

const EGLint configAttributes[] = {
    EGL_RED_SIZE,       8,
    EGL_GREEN_SIZE,     8,
    EGL_BLUE_SIZE,      8,
    EGL_ALPHA_SIZE,     8,
    EGL_DEPTH_SIZE,     24,
    EGL_STENCIL_SIZE,   8,
    EGL_SAMPLE_BUFFERS, 0,
    EGL_NONE
};
EGLConfig graphicsConfig;
EGLint configCount;
if(!eglChooseConfig(mainWindowDisplay, configAttributes, &graphicsConfig, 1, &configCount) || (configCount != 1)) {
    ...
}

EGLint surfaceAttributes[] = {
    EGL_POST_SUB_BUFFER_SUPPORTED_NV, EGL_TRUE,
    EGL_NONE
};
if(strstr(displayExtensions, "EGL_NV_post_sub_buffer") == nullptr) {
    surfaceAttributes[0] = EGL_NONE;
}
mainWindowSurface = eglCreateWindowSurface(mainWindowDisplay, graphicsConfig, window, &surfaceAttributes[0]);
if(eglGetError() != EGL_SUCCESS) {
    ...
}
assert(mainWindowSurface != EGL_NO_SURFACE);

EGLint contextAttributes[] = {
    EGL_CONTEXT_MAJOR_VERSION_KHR, 2,
    EGL_CONTEXT_MINOR_VERSION_KHR, 0,
    EGL_NONE
};
if(!hasKHRCreateContext) {
    contextAttributes[0] = EGL_CONTEXT_CLIENT_VERSION;
    contextAttributes[2] = EGL_NONE;
}
mainWindowContext = eglCreateContext(mainWindowDisplay, graphicsConfig, nullptr, &contextAttributes[0]);
if(eglGetError() != EGL_SUCCESS) {
    ...
}

eglMakeCurrent(mainWindowDisplay, mainWindowSurface, mainWindowSurface, mainWindowContext);
if(eglGetError() != EGL_SUCCESS) {
    ...
}

成功获取上下文后，glGetError（）始终返回GL_INVALID_OPERATION

1 个答案: