Fixing Disappearing Point After Position Update

Your code for updating the point's position looks correct at first glance. The issue might be related to one of several common problems when updating geometry attributes in Three.js:

Possible Issues and Solutions

1. Camera or Frustum Culling

When you move the point along the z-axis, it might be moving outside the camera's view frustum. This is especially likely if your camera has a narrow field of view or if the near/far planes are set too restrictively.

Solution:

• Check your camera settings (near, far, position, and lookAt)
• Temporarily increase the point size to make it more visible
• Try different z values (smaller increments) to see if it's a visibility issue

2. Incorrect Update Method

While your update code looks correct, there might be an issue with how the update is being processed.

Solution:
Try this alternative approach:

JAVASCRIPTCopied
this.rebarObjects.forEach((object) => {
    // Get the position attribute
    let positionAttribute = object.geometry.getAttribute('position');
    
    // Update the z value directly using the setAttribute method
    positionAttribute.setZ(0, 1); // Set z-coordinate of first vertex to 1
    
    // Mark the attribute as needing an update
    positionAttribute.needsUpdate = true;
});

3. Render Loop Issue

Make sure your scene is being re-rendered after the update.

Solution:
Ensure your update code is followed by a render call:

JAVASCRIPTCopied
// After updating all objects
renderer.render(scene, camera);

4. Material Issues

Sometimes point materials can behave unexpectedly when positions change.

Solution:
Try updating the material as well:

JAVASCRIPTCopied
this.rebarObjects.forEach((object) => {
    // Update position as before
    let positionAttribute = object.geometry.getAttribute('position');
    positionAttribute.setZ(0, 1);
    positionAttribute.needsUpdate = true;
    
    // Also update the material
    object.material.needsUpdate = true;
});

5. Depth Testing

The point might be hidden behind other objects or affected by depth testing.

Solution:
Try modifying the material's depth test properties:

JAVASCRIPTCopied
object.material.depthTest = false;
// or
object.material.depthWrite = false;

Additional Debugging Tips

1. Try adding a simple cube or sphere at the same position to verify if objects are visible at that location
2. Check if your scene has any clipping planes that might be affecting visibility
3. Verify that the point's size is appropriate for its distance from the camera
4. Ensure the point's material is not fully transparent

If none of these solutions work, you might need to provide more information about your camera setup and overall scene configuration.