Check For Opengl Error
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OpenGL and GLSL: gDebugger. Although not totally compatible with version 3.3, it still provides a very good job alerting opengl subsystem error us to errors in our code, allowing us to see the values
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of our uniforms, amongst many other features. Anyway, back to our code. When we call a function from opengl error 1282 the OpenGL API we may be calling it incorrectly, and this is what glGetError is good for. "Incorrectly" can mean several things, for instance, the parameters are not in opengl error 1280 a valid range, or a function is being called without a proper context. OpenGL does not detect every possible error that may occur. This is due to performance reasons. Error tracking takes its toll on performance, and error free applications would be delayed unnecessarily. Every time an error is detected a flag is set and a numeric code is recorded.
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Any errors after that won't be recorded so we need to make sure we check for errors at the most significant points in your application. To check if an error has occurred we use the function: GLenum glGetError(void); The return value can be one of the following: GL_INVALID_ENUM: a function has been called with an inappropriate enum. GL_INVALID_VALUE: A function has been called with a out of range numeric value. GL_INVALID_OPERATION: An operation has been performed out of context, or not allowed in the current state GL_INVALID_FRAMEBUFFER_OPERATION:vThe framebuffer object is not complete yet GL_OUT_OF_MEMORY: well, this one is pretty obvious… In all cases, except the last, the function produces no effect, i.e. the function is silently ignored. That is why it is so important to check for errors. In the last case, GL_OUT_OF_MEMORY, the outcome may be undefined. When an error is checked, the flag is cleared, and it will stay so until a new error occurs. Here are a few examples of errors: // causes a GL_INVALID_ENUM glEnable(GL_LINE); // causes a GL_INVALID_VALUE //when x >= GL_MAX_VERTEX_ATTRIBS glEnableVertexAttribArr
When an error occurs, the error flag is set to the appropriate error code value. No other errors are recorded until glGetError is called, the error opengl error 1281 code is returned, and the flag is reset to GL_NO_ERROR. If opengl error 0x0502 a call to glGetError returns GL_NO_ERROR, there has been no detectable error since the last call
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to glGetError, or since the GL was initialized. To allow for distributed implementations, there may be several error flags. If any single error flag has recorded http://www.lighthouse3d.com/cg-topics/error-tracking-in-opengl/ an error, the value of that flag is returned and that flag is reset to GL_NO_ERROR when glGetError is called. If more than one flag has recorded an error, glGetError returns and clears an arbitrary error flag value. Thus, glGetError should always be called in a loop, until it returns GL_NO_ERROR, if all https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGetError.xml error flags are to be reset. Initially, all error flags are set to GL_NO_ERROR. The following errors are currently defined: GL_NO_ERROR No error has been recorded. The value of this symbolic constant is guaranteed to be 0. GL_INVALID_ENUM An unacceptable value is specified for an enumerated argument. The offending command is ignored and has no other side effect than to set the error flag. GL_INVALID_VALUE A numeric argument is out of range. The offending command is ignored and has no other side effect than to set the error flag. GL_INVALID_OPERATION The specified operation is not allowed in the current state. The offending command is ignored and has no other side effect than to set the error flag. GL_INVALID_FRAMEBUFFER_OPERATION The command is trying to render to or read from the framebuffer while the currently bound framebuffer is not framebuffer complete (i.e. the return value from glCheckFramebufferStatus is not GL_FRAMEBUFFER_COMPLETE). The offending command is ignored and has no other sid
most likely done something you shouldn't. For example, tried to buffer more data than the allocated memory can hold, forgotten to upload data, forgotten to set correct uniforms, and so http://9bitscience.blogspot.com/2013/05/error-checking-in-opengl.html on. Now OpenGL can't help you with all of these - but if some buffer fails to allocate, or you pass an invalid enum, it can tell you about it. All you need http://stackoverflow.com/questions/16594425/is-there-a-better-way-of-debugging-opengl-than-calling-glgeterror-after-each-com to do is listen. Whenever you do something bad in OpenGL, an error flag is raised. You can figure out what functions raise which error flags by reading the man pages, which are opengl error actually quite pleasant to read. The following is a list of all the possible errors: GL_NO_ERROR GL_INVALID_ENUM GL_INVALID_VALUE GL_INVALID_OPERATION GL_INVALID_FRAMEBUFFER_OPERATION GL_STACK_UNDERFLOW GL_STACK_OVERFLOW GL_OUT_OF_MEMORY If any error flag, except for the last one, is raised, the command you were trying to execute is ignored; leaving the state of OpenGL unchanged. If the last one occurs, the state is undefined, which is really scary and you don't want that. check for opengl We can find out if an error occurred by calling glGetError(), which returns any of the above codes, as an enum. If multiple errors occurred and you want to see them all, you will need to call this function repeatedly until it returns GL_NO_ERROR flag. But this sort of global variable might be a source for confusion when debugging. For example: consider the function, void foo() { glBindBuffer(GL_ARRAY_BUFFER, &someBuffer); glBufferSubData(GL_ARRAY_BUFFER, offset, size, data) glBindBuffer(GL_ARRAY_BUFFER, 0); } Let's say the we try to send more data than the buffer has allocated memory for. The error flag will be set to GL_INVALID_VALUE, and our call to glBufferSubData() will do nothing. However, we do not check for errors in this function. Consider another function: void bar() { glBindBuffer(GL_ARRAY_BUFFER, &completelyDifferentBuffer); glBufferData(GL_ARRAY_BUFFER, size, NULL, usage); glBindBuffer(GL_ARRAY_BUFFER, 0); GLenum error = glGetError(); ... } This function does check for errors. Now here's the kicker: if this is the first place we do an error-check after the error flag was raised, we will discover the error here! The reason is that the error flag is only reset to GL_NO_ERROR when we call glGetError(). But this function is completely unrelated to the ot
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Is there a better way of debugging OpenGL than calling glGetError after each command? up vote 6 down vote favorite 1 I'm experimenting with some OpenGL on Android, and I don't have any previous experience with 3D programming. So obviously I made quite a few mistakes in my program. When I encountered a problem and found that glGetError produced an error code, I just added calls to glGetError after each call to an OpenGL command in my drawing code. While this worked and I found my errors this way, my drawing code is now twice as big and harder to read in my opinion. Is there a way to get rid of all these explicit calls to glGetError and just call it automatically? Preferably, my app should just abort with an error indicating which command is responsible if an OpenGL error occurs. android opengl-es share|improve this question asked May 16 '13 at 18:03 Mad Scientist 8,52654879 add a comment| 4 Answers 4 active oldest votes up vote 7 down vote As of version 4.2 Android offers an option called "Enable OpenGL traces" in the phone's developer options. If you set this to "Call stack on glGetError" you'll get an output like 07-15 15:44:43.045: D/libEGL(14251): [glEnableClientState] 0x500 07-15 15:44:43.068: D/CallStack(14251): glGetError:glEnableClientState#00 pc 00019388 /system/lib/libEGL.so 07-15 15:44:43.076: D/CallStack(14251): glGetError:glEnableClientState#01 pc 0001e290 /system/lib/libdvm.so (dvmPlatformInvoke+112) 07-15 15:44:43.076: D/CallStack(14251): glGetError:glEnableClientState#02 pc 0004d410 /system/lib/libdvm.so (dvmCallJNIMethod(unsigned int const*, JValue*,