more physics tweaks

game/aw.go

@@ -32,7 +32,8 @@ func (aw *Awakeman) Update() error {
 		ε             = 0.2
 		restitution   = -0.3
 		gravity       = 0.3
-		jumpVelocity = -3.6
+		airResistance = -0.01 // ∴ terminal velocity = 30
+		jumpVelocity  = -4
 		runVelocity   = 1.4
 		coyoteTime    = 5
 	)
@@ -55,8 +56,8 @@ func (aw *Awakeman) Update() error {
 		aw.vy = 0
 		aw.coyoteTimer = coyoteTime
 	} else {
-		// Falling. v = v_0 + a, and a is gravity.
-		aw.vy += gravity
+		// Falling. v = v_0 + a, and a = gravity + airResistance(v)
+		aw.vy += gravity + airResistance*aw.vy
 		if aw.coyoteTimer > 0 {
 			aw.coyoteTimer--
 		}