From e3c8e3bcc266f56eef91226b425daab3421d0551 Mon Sep 17 00:00:00 2001
From: Cyberarm <matthewlikesrobots@gmail.com>
Date: Sun, 25 Apr 2021 14:58:12 +0000
Subject: [PATCH] Added a bunch of tweens to the Animator, replaced
 :ease_in_out tween for Intro state engine logo to :swing_to

---
 lib/cyberarm_engine/animator.rb            | 167 ++++++++++++++++++++-
 lib/cyberarm_engine/builtin/intro_state.rb |   2 +-
 2 files changed, 166 insertions(+), 3 deletions(-)

diff --git a/lib/cyberarm_engine/animator.rb b/lib/cyberarm_engine/animator.rb
index 5be93df..7ec8cf4 100644
--- a/lib/cyberarm_engine/animator.rb
+++ b/lib/cyberarm_engine/animator.rb
@@ -43,14 +43,177 @@ module CyberarmEngine
       Gosu::Color.from_ahsv(alpha, hue, saturation, value)
     end
 
-    # NOTE: Use this for future reference? https://github.com/danro/easing-js/blob/master/easing.js
+    # Tween functions based on those provided here: https://github.com/danro/easing-js/blob/master/easing.js
+    # Under MIT / BSD
 
     def tween_linear(t)
       t
     end
 
-    def tween_ease_in_out(t)
+    def tween_ease_in_quad(t)
+      t ** 2
+    end
+
+    def tween_ease_out_quad(t)
+      -((t - 1) ** 2) -1
+    end
+
+    def tween_ease_in_out_quad(t)
+      return 0.5 * (t ** 2) if (t /= 0.5) < 1
+      return -0.5 * ((t -= 2) * t - 2)
+    end
+
+    def tween_ease_in_cubic(t)
+      t ** 3
+    end
+
+    def tween_ease_out_cubic(t)
+      ((t - 1) ** 3) + 1
+    end
+
+    def tween_ease_in_out_cubic(t)
+      return 0.5 * (t ** 3) if ((t /= 0.5) < 1)
+      return 0.5 * ((t - 2) ** 3) + 2
+    end
+
+    def tween_ease_in_quart(t)
+      t ** 4
+    end
+
+    def tween_ease_out_quart(t)
+      -((t - 1) ** 4) - 1
+    end
+
+    def tween_ease_in_out_quart(t)
+      return 0.5 * (t ** 4) if ((t /= 0.5) < 1)
+      return -0.5 * ((t -= 2) * (t ** 3) - 2)
+    end
+
+    def tween_ease_in_quint(t)
+      t ** 5
+    end
+
+    def tween_ease_out_quint(t)
+      ((t - 1) ** 5) + 1
+    end
+
+    def tween_ease_in_out_quint(t)
+      return 0.5 * (t ** 5) if ((t /= 0.5) < 1)
+      return 0.5 * ((t - 2) ** 5) + 2
+    end
+
+    def tween_ease_in(t) # sine
+      -Math.cos(t * (Math::PI / 2)) + 1
+    end
+
+    def tween_ease_out(t) # sine
+      Math.sin(t * (Math::PI / 2))
+    end
+
+    def tween_ease_in_out(t) # sine
       (-0.5 * (Math.cos(Math::PI * t) - 1))
     end
+
+    def tween_ease_in_expo(t)
+      (t == 0) ? 0 : 2 ** 10 * (t - 1)
+    end
+
+    def tween_ease_out_expo(t)
+      (t == 1) ? 1 : -(2 ** -10 * t) + 1
+    end
+
+    def tween_ease_in_out_expo(t)
+      return 0 if (t == 0)
+      return 1 if (t == 1)
+      return 0.5 * (2 ** 10 * (t - 1)) if ((t /= 0.5) < 1)
+      return 0.5 * (-(2 ** -10 * (t -= 1)) + 2)
+    end
+
+    def tween_ease_in_circ(t)
+      -(Math.sqrt(1 - (t * t)) - 1)
+    end
+
+    def tween_ease_out_circ(t)
+      Math.sqrt(1 - ((t - 1) ** 2))
+    end
+
+    def tween_ease_in_out_circ(t)
+      return -0.5 * (Math.sqrt(1 - t * t) - 1) if ((t /= 0.5) < 1)
+      return 0.5 * (Math.sqrt(1 - (t -= 2) * t) + 1)
+    end
+
+    def tween_ease_in_back(t)
+      s = 1.70158
+      t * t * ((s + 1) * t - s)
+    end
+
+    def tween_ease_out_back(t)
+      s = 1.70158
+      (t = t - 1) * t * ((s + 1) * t + s) + 1
+    end
+
+    def tween_ease_in_out_back(t)
+      s = 1.70158
+      return 0.5 * (t * t * (((s *= (1.525)) + 1) * t - s)) if ((t /= 0.5) < 1)
+      return 0.5 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2)
+    end
+
+    def tween_elastic(t)
+      -1 * (4 ** (-8 * t)) * Math.sin((t * 6 - 1) * (2 * Math::PI) / 2) + 1
+    end
+
+    def tween_swing_from_to(t)
+      s = 1.70158
+      return 0.5 * (t * t * (((s *= (1.525)) + 1) * t - s)) if (t /= 0.5) < 1
+      return 0.5 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2)
+    end
+
+    def tween_swing_from(t)
+      s = 1.70158;
+      t * t * ((s + 1) * t - s)
+    end
+
+    def tween_swing_to(t)
+      s = 1.70158
+      (t -= 1) * t * ((s + 1) * t + s) + 1
+    end
+
+    def tween_bounce(t)
+      if (t < (1 / 2.75))
+        (7.5625 * t * t)
+      elsif (t < (2 / 2.75))
+        (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75)
+      elsif (t < (2.5 / 2.75))
+        (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375)
+      else
+        (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375)
+      end
+    end
+
+    def tween_bounce_past(t)
+      if (t < (1 / 2.75))
+        # missing "2 -"?
+        (7.5625 * t * t)
+      elsif (t < (2 / 2.75))
+        2 - (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75)
+      elsif (t < (2.5 / 2.75))
+        2 - (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375)
+      else
+        2 - (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375)
+      end
+    end
+
+    def tween_ease_from_to(t)
+      return 0.5 * (t ** 4) if ((t /= 0.5) < 1)
+      return -0.5 * ((t -= 2) * (t ** 3) - 2)
+    end
+
+    def tween_ease_from(t)
+      t ** 4
+    end
+
+    def tween_ease_to(t)
+      t ** 0.25
+    end
   end
 end
diff --git a/lib/cyberarm_engine/builtin/intro_state.rb b/lib/cyberarm_engine/builtin/intro_state.rb
index 7a16616..10bda76 100644
--- a/lib/cyberarm_engine/builtin/intro_state.rb
+++ b/lib/cyberarm_engine/builtin/intro_state.rb
@@ -33,7 +33,7 @@ module CyberarmEngine
         Animator.new(start_time: base_time +  500,  duration: 1_000, from: 0.0, to: 1.0, tween: :ease_in_out),
         Animator.new(start_time: Gosu.milliseconds + @continue_after - 1_000,  duration: 1_000, from: 0.0, to: 1.0, tween: :ease_in_out),
 
-        Animator.new(start_time: Gosu.milliseconds + 250, duration: 500, from: 0.0, to: 1.0, tween: :ease_in_out) # CyberarmEngine LOGO
+        Animator.new(start_time: Gosu.milliseconds + 250, duration: 500, from: 0.0, to: 1.0, tween: :swing_to) # CyberarmEngine LOGO
       ]
     end