23 — Raycaster and Mouse Events

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• test if an object is behind the mouse

• shoot a ray through and see if those spheres intersect

• Instantiate a Raycaster

• change the position and direction where ray will be cast, we can use the set(...)

• first parameter is the position and the second parameter is the direction

• direction has to be normalized. A normalized vector has a length of 1. Don't worry, you don't have to do the mathematics by yourself, and you can call the normalize() method on the vector

• normalize() method making sure that the vector is 1 unit long

• cast a ray and get the objects that intersect

• intersection is always an array

• ray can go through the same object multiple times. Imagine a donut

• returned array contains much useful information

• test if there is a wall in front of the player, you can test the distance

• change the object's color, you can update the object's material

• show an explosion on the impact point, you can create this explosion at the point position

• things while they are moving, we have to do the test on each frame

• update our raycaster like we did before but in the tick function

• now update the material of the object property for each item of the intersects

• they all go blue but never go back red

• turn all the spheres red and then turn the ones that intersect blue

• need to cast a ray from the camera in the mouse's direction