glsl view position of the camera based on the model position in three.js

vertex.glsl

/* calculate view position of the camera */

out vec3 vViewDirection;

void main()
{

  vec4 worldPosition = modelMatrix * vec4( position, 1.0 );


  vViewDirection = normalize( cameraPosition - worldPosition.xyz );


  gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

}