The default scroll-rig camera is locked to a 50 degree Field-of-View.

In order to perfectly match DOM dimensions, the camera distance will be calculated. This calculation is based on screen height since Threejs uses a vertical FoV. This means the camera position-z will change slightly based on your height.

You can override the default camera behaviour, and for instance set the distance and have a variable FoV instead:

<GlobalCanvas camera={{ position: [0, 0, 10] }} />

Or change the FoV, which would move the camera further away in this case:

<GlobalCanvas camera={{ fov: 20 }} />

If you need full control of the camera you can pass in a custom camera as a child instead.

The scale is always matching the tracked DOM element and will update based on media queries etc.

<ScrollScene track={el}>
  {{ scale }} => (
  <mesh scale={scale} />
  )}
</ScrollScene>

Scale is a 3-dimensional vector type from vecn that support swizzling and object notation. You can do things like:

position.x === position[0]
position.xy => [x,y]
scale.xy.min() => Math.min(scale.x, scale.y)

By default the scroll-rig will calculate the camera FoV so that 1 pixel = 1 viewport unit.

In some cases, this can mess up the depth sorting, leading to visual glitches in a 3D model. A 1000 pixel wide screen would make the scene 1000 viewport units wide, and by default the camera will also be positioned ~1000 units away in Z-axis (depending on the FoV and screen hight).

One way to fix this is to enable the logarithmicDepthBuffer but that can be bad for performance.

A better way to fix the issue is to change the GlobalCanvas scaleMultiplier to something like 0.01 which would make 1000px = 10 viewport units.

<GlobalCanvas scaleMultiplier={0.01} />

The scaleMultiplier setting updates all internal camera and scaling logic. Hardcoded scales and positions would need to be updated if you change this setting.

By default R3F uses ACES Filmic tone mapping which makes 3D scenes look great.

However, if you need to match hex colors or show editorial images, you can disable it per material like so:

<meshBasicMaterial toneMapping={false} />

All items on the page should have a predictable height - always define an aspect ratio using CSS for images and other interactive elements that might impact the document height as they load.

The scroll-rig uses ResizeObserver to detect changes to the document.body height, for instance after webfonts loaded, and will automatically recalculate postions.

If this fails for some reason, you can trigger a manual reflow() to recalculate all cached positions.

const { reflow } = useScrollRig()

useEffect(() => {
  heightChanged && reflow()
}, [heightChanged])

• Use CSS animations whenever possible instead of JS for maximum smoothness
• Consider disabling SmoothScrollbar and all scrolling WebGL elements on mobile - it is usually laggy.
• Make sure you read, understand and follow all performance recomendations associated with React and three:

This is possible in R3F by re-attaching the event system to a parent of the canvas:

const ref = useRef()
return (
  <div ref={ref}>
    <GlobalCanvas
      eventSource={ref} // rebind event source to a parent DOM element
      eventPrefix="client" // use clientX/Y for a scrolling page
      style={{
        pointerEvents: 'none', // delegate events to wrapper
      }}
    />
  </div>
)

Yes, events will be correctly tunneled into the viewport, if you follow the steps above to re-attach the event system to a parent of the canvas.

The CodeSandbox editor runs in an iframe which breaks the IntersectionObserver's rootMargin. If you open the example outside the iframe, you'll see it's working as intended.

This is know issue.

This is a known issue with the UseCanvas component.

You can either use the useCanvas() hook instead, or make HMR work again by defining your children as top level functions instead of inlining them:

// HMR will work on me since I'm defined here!
const MyScrollScene = ({ el }) => <ScrollScene track={el}>/* ... */</ScrollScene>

function MyHtmlComponent() {
  return (
    <UseCanvas>
      <MyScrollScene />
    </UseCanvas>
  )
}

A similar issue exist in tunnel-rat.

The scroll-rig runs a custom render loop of the global scene inside r3f. It runs with priority 1000.

You can disable the global render loop using globalRender or change the priority with the globalPriority props on the <GlobalCanvas>. You can still schedule your own render passes before or after the global pass using useFrame with your custom priority.

The main reason for running our own custom render pass instead of the default R3F render, is to be able to avoid rendering when no meshes are in the viewport. To enable this you need to set frameloop="demand" on the GlobalCanvas.

If the R3F frameloop is set to demand - the scroll rig will make sure global renders and viewport renders only happens if it's needed.

To request global render call requestRender() from useScrollRig on each frame. ScrollScene will do this for you when the mesh is in viewport.

This library also supports rendering separate scenes in viewports as a separate render pass by calling renderViewport(). This way we can render scenes with separate lights or different camera than the global scene. This is how ViewportScrollScene works.

In this scenario you also need to call invalidate to trigger a new R3F frame.

Post processing runs in a separate pass so you need to manually disable the global render loop to avoid double renders.

<GlobalCanvas globalRender={false} scaleMultiplier={0.01}>
  <Effects />
</GlobalCanvas>

Note: ViewportScrollScene will not be affected by global postprocessing effects since it runs in a separate render pass.

Please read the API docs on using children as a render function for an example.