glGenQueries always return non-query objects, glBeginQuery return error

Question

I'm trying to create an occlusion query using openGL 3.3, using GLFW, GLEW

load function:

uint32_t glQueryID;
glGenQueries(1, &glQueryID);
if (glIsQuery(glQueryID)) //just for testing its always false !
{
 ... it must be always true !?!
}

draw function:

glBeginQuery(GL_ANY_SAMPLES_PASSED, glQueryID);
glGetError();// 1282 invalid operation

However all my other glCalls worked correctly without any error

Running on Mac OS X, intel HD 4000

Is there some reason why you insist on asking OpenGL if it did the thing you told it to do? — Nicol Bolas, Mar 25 '17 at 18:12
Don't you love OpenGL, where calling `glGenFoo` doesn't generate any `Foo`, only binding / using them for the first time actually does? — peppe, Mar 25 '17 at 19:35
Hahahaha, yes i love it, and yes that is the reason ! thanks — mofed8461, Mar 25 '17 at 19:40

score 2 · Answer 1 · edited Jun 20 '20 at 09:12

2

From the documentation of glIsQuery:

glIsQuery returns GL_TRUE if id is currently the name of a query object. If id is zero, or is a non-zero value that is not currently the name of a query object, or if an error occurs, glIsQuery returns GL_FALSE.

A name returned by glGenQueries, but not yet associated with a query object by calling glBeginQuery, is not the name of a query object.

Since you call glIsQuery before assinging a query object to it (for example by calling glBeginQuery), the return value has to be GL_FALSE.

edited Jun 20 '20 at 09:12

Community

1
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answered Mar 25 '17 at 18:17

BDL

21,052
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Thanks very much, I would mention that the problem was solved by initialize the query with empty begin and end .. i don't know what was the cause of invalid operation error `glGenQueries(1, &glQueryID); glBeginQuery(GL_SAMPLES_PASSED, glQueryID); glEndQuery(GL_SAMPLES_PASSED);` – mofed8461 Mar 25 '17 at 18:30

score 0 · Answer 2 · answered Mar 25 '17 at 18:34

0

The problem was solved by initializing query followed by empty begin/end Query

glGenQueries(1, &glQueryID);
glBeginQuery(GL_SAMPLES_PASSED, glQueryID);
glEndQuery(GL_SAMPLES_PASSED);

this will fix error 1282 (invalid operation) when drawing later

answered Mar 25 '17 at 18:34

mofed8461

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glGenQueries always return non-query objects, glBeginQuery return error

2 Answers2