From cbd45ffc92d7bd842ec000dc98e93ac229efba51 Mon Sep 17 00:00:00 2001 From: Skye Terran Date: Thu, 5 Aug 2021 22:15:18 -0700 Subject: [PATCH] Working sync version of the game loop Main problem here is that display() is blocked by update() and the update rate will slow down if the display rate slows below the update rate --- .gitignore | 1 + Cargo.lock | 181 ++++++++++++++++++++++++++++++++++++++++++++++++++++ Cargo.toml | 9 +++ src/main.rs | 83 ++++++++++++++++++++++++ 4 files changed, 274 insertions(+) create mode 100644 .gitignore create mode 100644 Cargo.lock create mode 100644 Cargo.toml create mode 100644 src/main.rs diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..ea8c4bf --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +/target diff --git a/Cargo.lock b/Cargo.lock new file mode 100644 index 0000000..3526733 --- /dev/null +++ b/Cargo.lock @@ -0,0 +1,181 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 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"8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3" diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..93ad564 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,9 @@ +[package] +name = "loopcore" +version = "0.1.0" +edition = "2018" + +# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html + +[dependencies] +futures = "0.3.16" \ No newline at end of file diff --git a/src/main.rs b/src/main.rs new file mode 100644 index 0000000..ce2223f --- /dev/null +++ b/src/main.rs @@ -0,0 +1,83 @@ +use std::time::Instant; +const UPDATE_INTERVAL: u32 = 40; + +fn main() { + // track the update delay's exponential moving average (EMA) + let mut frame_delay_ema: f64 = 0.0; + + // track the latest delays + let mut frame_delay: u32 = 0; + let mut tick_delay: u32 = 0; + + loop { + // start per-loop delay timer + let timer = Instant::now(); + + // DEBUG - track if a tick has happened on this frame + let mut ticked: bool = false; + + // update (game logic, etc.) + // executes every UPDATE_INTERVAL milliseconds at maximum + if tick_delay >= UPDATE_INTERVAL { + // perform all per-tick logic here + update(); + + // reset the tick delay + tick_delay = 0; + + // DEBUG + ticked = true; + } + + // display (rendering) + // executes as fast as possible + { + display(); + } + + // get the current frame delay, update the frame delay EMA and the tick delay + frame_delay = timer.elapsed().as_millis() as u32; + frame_delay_ema = lerp_1d(frame_delay_ema, frame_delay as f64, 0.1f64); + tick_delay += frame_delay; + + // debug + let frame_rate = (1000.0f64 / frame_delay_ema as f64) as u32; + if ticked { + println!("Frame Delay: {}ms | Frame Rate: {}Hz | Ticked!", frame_delay, frame_rate); + } else { + println!("Frame Delay: {}ms | Frame Rate: {}Hz", frame_delay, frame_rate); + } + } +} + +// update function +fn update() { + waste_time(64); +} + +// render function +fn display() { + waste_time(16); +} + +// 1D linear interpolation +fn lerp_1d(x: f64, y: f64, a: f64) -> f64 { + x + ((y - x) * a) +} + +// busywork function +fn waste_time(repeat: u32) { + const BUFFER_RESOLUTION: usize = 512; + + // create an RGBA buffer and change every pixel one-by-one + let mut rgba_buffer = vec![[[0.0f32; 4]; BUFFER_RESOLUTION]; BUFFER_RESOLUTION]; + + // change every pixel in the buffer (repeat) times + for _n in 0..repeat { + for u in 0..BUFFER_RESOLUTION { + for v in 0..BUFFER_RESOLUTION { + rgba_buffer[u][v] = [1.0f32; 4]; + } + } + } +} \ No newline at end of file