camera shake

1 files changed, 43 insertions, 3 deletions

diff --git a/src/camera.lua b/src/camera.lua
index 31bfe9e..add6ae4 100644
--- a/src/camera.lua
+++ b/src/camera.lua
@@ -1,5 +1,7 @@
 local DEFAULT_CAMERA_SMOOTHING = 30
 
+local SHAKE_NOISE_SPEED = 15
+
 Cam = {}
 Cam.__index = Cam
 
@@ -14,12 +16,24 @@ function Cam.new(x, y)
 
   self.smoothing = DEFAULT_CAMERA_SMOOTHING
 
+  self.shake_strength = 0
+  self.shake_timer_max = 0
+  self.shake_timer = 0
+
+  self.shake_damp = EASING_FUNCTIONS.Lerp
+  self.shake_noise = lmath.noise
+
   return self
 end
 
 function Cam:update(dt)
   self.realx = dlerp(self.realx, self.x, self.smoothing * dt)
   self.realy = dlerp(self.realy, self.y, self.smoothing * dt)
+
+  self.shake_timer = self.shake_timer - dt
+  if self.shake_timer < 0 then
+    self.shake_strength = 0
+  end
 end
 
 local active_cam = Cam.new()
@@ -28,6 +42,16 @@ function get_active_camera()
   return active_cam
 end
 
+function Cam:shake(strength, time)
+  if strength < self.shake_strength then
+    return
+  end
+  self.noise_seed = lmath.random() * 1000
+  self.shake_strength = strength
+  self.shake_timer = time
+  self.shake_timer_max = time
+end
+
 function set_active_camera(new_cam)
   active_cam = new_cam
 end
@@ -35,7 +59,23 @@ end
 function use_camera_transform()
   local w, h = SCR_WIDTH / 2, SCR_HEIGHT / 2
   lg.scale(active_cam.zoom)
-  lg.translate(
-    round(-active_cam.realx + w / active_cam.zoom),
-    round(-active_cam.realy + h / active_cam.zoom))
+  local ox, oy = round(-active_cam.realx + w / active_cam.zoom),
+                 round(-active_cam.realy + h / active_cam.zoom)
+
+  local shakex, shakey = 0, 0
+  if active_cam.shake_timer > 0 then
+    shakex = active_cam.shake_noise(
+      active_cam.shake_timer * SHAKE_NOISE_SPEED + active_cam.noise_seed)
+
+    shakey = active_cam.shake_noise(
+      -- 100 is a magic number to offset the x and y noise (so its not just a diagonal shake)
+      active_cam.shake_timer * SHAKE_NOISE_SPEED + active_cam.noise_seed, 100)
+
+    local anim = active_cam.shake_timer / active_cam.shake_timer_max
+    local strength = active_cam.shake_strength * active_cam.shake_damp(0, 1, anim)
+    shakex = shakex * strength
+    shakey = shakey * strength
+  end
+
+  lg.translate(ox + shakex, oy + shakey)
 end