Events and Interaction

This tutorial will assume some React knowledge, and will be based on this starter codesandbox, so just fork it and follow along!

After we have our continuous loop running the next step would be to allow our mesh to react to user interaction, so in this part let's attach a click handler to the cube and make it bigger on click.

Any Object3D that has a raycast method can receive a large number of events, for instance a mesh:

<mesh
  onClick={(e) => console.log('click')}
  onContextMenu={(e) => console.log('context menu')}
  onDoubleClick={(e) => console.log('double click')}
  onWheel={(e) => console.log('wheel spins')}
  onPointerUp={(e) => console.log('up')}
  onPointerDown={(e) => console.log('down')}
  onPointerOver={(e) => console.log('over')}
  onPointerOut={(e) => console.log('out')}
  onPointerEnter={(e) => console.log('enter')}
  onPointerLeave={(e) => console.log('leave')}
  onPointerMove={(e) => console.log('move')}
  onPointerMissed={() => console.log('missed')}
  onUpdate={(self) => console.log('props have been updated')}
/>

From this we can see that what we need to do is use the old onClick event we use on any DOM element to react to a user clicking the mesh.

Let's add it then:

<mesh onClick={() => alert('Hellooo')} ref={myMesh}>
  <boxGeometry />
  <meshPhongMaterial color="royalblue" />
</mesh>

We did it! We created the most boring interaction in the story of 3D and we made an alert show up. Now let's make it actually animate our mesh.

Let's start by setting some state to check if the mesh is active:

const [active, setActive] = useState(false)

After we have this we can set the scale with a ternary operator like so:

<mesh scale={active ? 1.5 : 1} onClick={() => setActive(!active)} ref={myMesh}>
  <boxGeometry />
  <meshPhongMaterial color="royalblue" />
</mesh>

If you try to click on your mesh now, it scales up and down. We just made our first interactive 3D mesh!

What we did in this chapter was:

• Attached a click handler to our mesh
• Added some state to track if the mesh is currently active
• Changed the scale based on that state

interaction

Exercises

• Change other props of the mesh like the position or even the color of the material.
• Use onPointerOver and onPointerOut to change the props of the mesh on hover events.

We just made our mesh react to user interaction but it looks pretty bland without any transition, right? In the next chapter let's integrate react-spring into our project to make this into an actual animation.