setColorAt( index, color ) {

		if ( this.instanceColor === null ) {

			this.instanceColor = new InstancedBufferAttribute( new Float32Array( this.instanceMatrix.count * 3 ).fill( 1 ), 3 );

		}

		color.toArray( this.instanceColor.array, index * 3 );

	}
Sets the given color to the defined instance. Make sure you set the `needsUpdate` flag of
{@link InstancedMesh#instanceColor} to `true` after updating all the colors.

@param {number} index - The instance index.
@param {Color} color - The instance color.