minor typo fixes: "it's" to "its"

threejs/lessons/threejs-cameras.md

@@ -507,7 +507,7 @@ camera.zoom = 1;
 
 Then let's load 6 textures and make 6 planes, one for each texture.
 We'll parent each plane to a `THREE.Object3D` to make it easy to offset
-the plane so it's center appears to be at it's top left corner.
+the plane so its center appears to be at its top left corner.
 
 ```js
 const loader = new THREE.TextureLoader();

threejs/lessons/threejs-game.md

@@ -2117,7 +2117,7 @@ we'd have had to switch to a `FiniteStateMachine`.
 It also wasn't clear to me if coroutines should run independently of their
 components. We could have made a global `CoroutineRunner` and put all
 coroutines on it. That would make cleaning them up harder. As it is now
-if the gameobject is removed all of it's components are removed and
+if the gameobject is removed all of its components are removed and
 therefore the coroutine runners created are no longer called and it will
 all get garbage collected. If we had global runner then it would be
 the responsibility of each component to remove any coroutines it added

threejs/lessons/threejs-picking.md

@@ -278,7 +278,7 @@ const pickingScene = new THREE.Scene();
 pickingScene.background = new THREE.Color(0);
 ```
 
-Then, for each cube we place in the main scene we make a corresponding "picking cube" at the same position as the original cube, put it in the `pickingScene`, and set it's material to something that will draw the object's id as its color. Also we keep a map of ids to objects so when we look up an id later we can map it back to its corresponding object.
+Then, for each cube we place in the main scene we make a corresponding "picking cube" at the same position as the original cube, put it in the `pickingScene`, and set its material to something that will draw the object's id as its color. Also we keep a map of ids to objects so when we look up an id later we can map it back to its corresponding object.
 
 ```js
 const idToObject = {};

threejs/lessons/threejs-scenegraph.md

@@ -153,7 +153,7 @@ We made the `earthMesh` a child of the `sunMesh`. The `sunMesh` has
 its scale set to 5x with `sunMesh.scale.set(5, 5, 5)`. That means the
 `sunMesh`s local space is 5 times as big. Anything put in that space
  will be multiplied by 5. That means the earth is now 5x larger and
- it's distance from the sun (`earthMesh.position.x = 10`) is also
+ its distance from the sun (`earthMesh.position.x = 10`) is also
  5x as well.
 
  Our scene graph currently looks like this
@@ -400,7 +400,7 @@ For the target, the thing the tank is aiming at, there is a `targetOrbit`
 offset from the `targetOrbit` and a base elevation. Childed to that is another
 `Object3D` called `targetBob` which just bobs up and down relative to the
 `targetElevation`. Finally there's the `targetMesh` which is just a cube we
-rotate and change it's colors
+rotate and change its colors
 
 ```js
 // move target
@@ -457,7 +457,7 @@ turretCamera.lookAt(targetPosition);
 ```
 
 There is also a `targetCameraPivot` which is a child of `targetBob` so it floats
-around with the target. We aim that back at the tank. It's purpose is to allow the
+around with the target. We aim that back at the tank. Its purpose is to allow the
 `targetCamera` to be offset from the target itself. If we instead made the camera
 a child of `targetBob` and just aimed the camera itself it would be inside the
 target.

threejs/lessons/threejs-webvr-look-to-select.md

@@ -381,7 +381,7 @@ otherwise the cursor won't be rendered.
 ```
 
 We then check if the thing we're picking this time is the same as it was last
-time. If so we add the elapsed time to a timer and if the timer reaches it's
+time. If so we add the elapsed time to a timer and if the timer reaches its
 limit we return the selected item.
 
 Now let's use that to pick the cubes. As a simple example
@@ -403,7 +403,7 @@ const boxDepth = 1;
 
 Then let's create 3 pairs of box and sphere meshes. We'll
 use a [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)
-so that we can associate each `Mesh` with it's partner.
+so that we can associate each `Mesh` with its partner.
 
 ```js
 -const cubes = [