module Eagle::Clock

Overview

Frame timing you can read from anywhere: how long the last frame took, how long the game has been running, the frame rate, and a global time scale.

The dt passed to App#update and Node#process is the same as Clock.delta. Multiply speeds by it so movement is the same at any frame rate.

.scale slows down or speeds up everything that uses .delta: set it to 0.3 for slow motion or 0 to freeze gameplay while menus keep working through .raw_delta.

class Hud < Node2D
  def draw(g : Graphics) : Nil
    g.print("fps #{Clock.fps.round}  t=#{Clock.elapsed.round(1)}s", 10, 10)
  end
end

Clock.scale = 0.25 # bullet time
pulse = Math.sin(Clock.elapsed * 4) # a value that oscillates over time

Defined in:

eagle/core/clock.cr

Class Method Summary

• .delta : Float32

  Seconds since the last frame, multiplied by .scale.

• .elapsed : Float64

  Real seconds since the engine started.

• .fixed_alpha : Float32

  How far the current frame sits between the last fixed step and the next, from 0 to 1.

• .fixed_delta : Float32

  Length of one fixed step in seconds, which is 1 / Config#fixed_fps.

• .fixed_delta=(v : Number)

  Changes the fixed step length.

• .fps : Float32

  Measured frames per second, updated twice a second.

• .frame : Int64

  Number of frames since start.

• .max_delta=(v : Number)

  Largest .delta a single frame can report, 0.25 s by default.

• .raw_delta : Float32

  Seconds since the last frame, ignoring .scale.

• .scale : Float32

  Time scale applied to .delta: 1 is normal, 0.5 is half speed and 0 pauses gameplay.

• .scale=(v : Number)

  Sets the time scale.

Class Method Detail