Struct glium::debug::TimestampQuery

pub struct TimestampQuery { /* fields omitted */ }

Allows you to obtain the timestamp inside the OpenGL commands queue.

When you call functions in glium, they are not instantly executed. Instead they are added in a commands queue that the backend executes asynchronously.

When you call TimestampQuery::new, a command is added to this list asking the backend to send us the current timestamp. Thanks to this, you can know how much time it takes to execute commands.

Example

let before = glium::debug::TimestampQuery::new(&display);
// do some stuff here
let after = glium::debug::TimestampQuery::new(&display);

match (after, before) {
    (Some(after), Some(before)) => {
        let elapsed = after.get() - before.get();
        println!("Time it took to do stuff: {}", elapsed);
    },
    _ => ()
}

Implementations

impl TimestampQuery

pub fn new<F: ?Sized>(facade: &F) -> Option<TimestampQuery> where
    F: Facade, 

Creates a new TimestampQuery. Returns None if the backend doesn't support it.

pub fn is_ready(&self) -> bool

Queries the counter to see if the timestamp is already available.

It takes some time to retrieve the value, during which you can execute other functions.

pub fn get(self) -> u64

Returns the value of the timestamp. Blocks until it is available.

This function doesn't block if is_ready returns true.