Layered cameras in Blender?

[Rob_F (robyer1)]

I have a scene in Blender for a product viewer where I have postprocessing on for the product like Bloom, depth of field etc but I want to recreate an effect I had in a Unity project where I had a camera that only rendered one layer and rendered it on top of the main camera so that hotspots and worldspace UI was excluded from post processing. Is this possible in the Blender version of Needle?

[needle-assistant (Needle Engine Assistant)]

To achieve layered camera rendering in Blender with Needle Engine, similar to Unity’s approach, you can utilize multiple cameras where one camera is specifically used for certain layers like UI or hotspots, and another camera for the main scene with post-processing effects.

Here’s a general approach:

1. Setup Multiple Cameras:

   • Create two cameras in your Blender scene. One camera will be for the main product with all post-processing effects and another for hotspots and UI.

2. Use Layers (Collections):

   • Separate objects into different collections in Blender. Main products and scenes in one collection and UI/hotspots in another.

3. Camera Layers:

   • Assign the respective collection to be visible only on the matching camera. For instance, make the main camera ignore the UI/hotspots by adjusting its visibility settings.

4. Post-processing:

   • Apply post-processing effects only to the main camera using Blender’s compositor or when setting up through Needle Engine scripts if available.

5. Render Order:

   • Ensure the rendering order is correct so that the UI/hotspot camera renders after the main camera to overlay the scene properly.

6. Needle Integration:

   • Needle Engine supports such setups, allowing for customization and various scripting to adjust camera properties dynamically. Utilize the Needle Engine API and component system to control this.

Refer to the Blender and Multi-Camera Needle Engine sample for practical implementation (see the documentation). Also, the Needle Engine documentation provides insights into components and camera control functionalities (see the documentation).

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[Rob_F (robyer1)]

Can you give me an example of a script to filter the layers the camera sees in Blender for Needle?

[needle-assistant (Needle Engine Assistant)]

Certainly, robyer1. Below is an example of how to filter the layers that a camera sees in Blender using Needle Engine.

Pseudocode Plan

1. Access the Camera: Get a reference to the camera object you want to configure.
2. Set Layer Visibility: Define which collections (layers) should be visible to the camera by using the camera’s settings.
3. Control Rendering Order: Ensure the camera renders last if needed.

Example Code

import { Camera, Layer } from "@needle-tools/engine";

// Function to set camera layer visibility
function setCameraLayerVisibility(camera, visibleLayers) {
    // Clear current visible layers
    camera.layers.clear();
  
    // Add specified layers to the camera's visible layers
    for (let layer of visibleLayers) {
        camera.layers.enable(layer);
    }
}

// Main function
function setupCameras() {
    // Get reference to your main camera
    const mainCamera = Camera.main;

    // Set the layers you want this camera to render (e.g., only main product layer)
    const mainVisibleLayers = [Layer.LAYER_0]; // Assuming your main product is in Layer 0
    setCameraLayerVisibility(mainCamera, mainVisibleLayers);
    
    // If you have another camera for UI/hotspots
    const uiCamera = new Camera(); // Create a new camera for UI
    const uiVisibleLayers = [Layer.LAYER_1]; // Assuming UI is in Layer 1
    setCameraLayerVisibility(uiCamera, uiVisibleLayers);

    // Ensure correct render order if necessary
    // This may involve setting the uiCamera to render after the mainCamera
}

// Call the main function
setupCameras();

Explanation

• The setCameraLayerVisibility function clears the current camera layers and adds new specified layers.
• The setupCameras function initializes the cameras and sets their visibility accordingly.

Ensure you customize layer indices based on your Blender setup. This should help you manage which objects are rendered by each camera. You may also adjust rendering order based on your specific needs in Needle Engine.

For more resources, check out the Needle Engine API documentation (see releases).

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[Rob_F (robyer1)]

Layer.LAYER_1 isn’t returning anything, I am also having issues with making a publicly assignable camera on the Component in Blender like so @serializable()
uiCam: Object;, if I try @serializable() uiCam: Camera; then I get errors in Blender that Camera isn’t defined

[needle-assistant (Needle Engine Assistant)]

Hi robyer1. Let’s address both of your issues.

1. Layer Visibility

If Layer.LAYER_1 isn’t returning anything, ensure:

• You have assigned objects to the correct layer in Blender.
• Use Layer.getLayerIndex("LayerName") if using named layers, adapting the code accordingly.

2. Assigning Public Camera Variable

When defining a publicly assignable camera variable in your component, you need to consider the import and structure. The Camera type might not be importing correctly.

Here’s an example of how to define a public camera variable correctly:

import { Camera, Serializable } from "@needle-tools/engine";

// Define the component with a publicly assignable camera
class MyComponent {
    @Serializable()
    uiCam: Camera | null = null;

    // Additional methods or constructor
}

// Ensure the camera is properly assigned in the editor

Notes

• Always make sure you have the correct imports and that the Camera type is being recognized by your script.
• If the Camera type still generates errors, check your Needle Engine version or the settings in Blender. It might need an import path adjustment or an update to the Needle Engine itself.

For specific version compatibility and class definitions, refer to the latest Needle Engine API (see releases). If problems persist, please provide the version of Blender and Needle Engine you are using for further assistance.

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[Rob_F (robyer1)]

Type Camera doesn’t exist in Blender, what object type should I use to assign the camera to the script in Blender?

[needle-assistant (Needle Engine Assistant)]

Hi robyer1. In Blender, especially when working with Needle Engine, the type for a camera object isn’t explicitly defined as Camera. Instead, you should use a more generic object type like Object for your camera variable in the script.

Here’s how you can adjust your code:

import { Serializable } from "@needle-tools/engine";

// Define the component with a publicly assignable camera
class MyComponent {
    @Serializable()
    uiCam: Object | null = null; // Use Object type instead of Camera

    // Additional methods or constructor
}

// Ensure the camera is properly assigned in the editor

Explanation

• By using Object, you can assign any Blender object, including cameras, without type issues.

Additional Tips

• Make sure to perform any necessary type checks or casts within your methods if you expect this object to specifically be a camera during runtime.
• Always test if the assigned object behaves as expected, especially when invoking camera-specific methods.

For further assistance, refer to the Needle Engine documentation for compatibility details (see the documentation). If you have more questions, feel free to ask!

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[Rob_F (robyer1)]

In Needle for Blender, how do I set the camera layer here to be layer 1?

  onEnable() {
    // getting the Camera component from the same GameObject
    this.cam = this.gameObject.getComponent(Camera);
    if (!this.cam) {
      console.warn("CameraLayer requires a Camera component");
      this.enabled = false;
    }
    // Clear current visible layers
    this.cam.layers.clear();
  }

[needle-assistant (Needle Engine Assistant)]

Hi robyer1. You can set the camera to only render a specific layer (in this case, layer 1) by enabling that layer after clearing the current visible layers. Below is how you can modify your onEnable method to achieve this:

onEnable() {
    // Getting the Camera component from the same GameObject
    this.cam = this.gameObject.getComponent(Camera);
    if (!this.cam) {
        console.warn("CameraLayer requires a Camera component");
        this.enabled = false;
        return; // Early return if there's no Camera component
    }
    
    // Clear current visible layers
    this.cam.layers.clear();
    
    // Set the camera to render only layer 1
    this.cam.layers.enable(1); // Assuming layer 1 corresponds to what you want
}

Explanation

• After clearing the current layers using this.cam.layers.clear();, you enable layer 1 using this.cam.layers.enable(1);.
• Indexing for layers typically starts at 0; ensure layer 1 represents the correct layer in Blender where your objects are located.

With this setup, your camera will now exclusively render objects assigned to layer 1. If there are any further issues or questions, feel free to ask!

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[Rob_F (robyer1)]

How do I disable rendering post processing volumes on that camera?

[Rob_F (robyer1)]

@marcel sorry for the tag, I am trying to use Needle Object Layers for this - I can’t seem to disable the Default or 0 layer on a camera in Blender here. Is there something I missed? The AI bot above got me so far, I disabled the aspect correction line just so I could easily see what each camera is rendering.

import { Behaviour, Camera } from "@needle-tools/engine";
import { PerspectiveCamera } from "three";

export class CameraLayer extends Behaviour {
  private cam: PerspectiveCamera | null = null;

  start() {
    // getting the Camera component from the same GameObject
    this.cam = this.gameObject.getComponent(Camera);
    if (!this.cam) {
      console.warn("CameraLayer requires a Camera component");
      this.enabled = false;
    }
    // Clear current visible layers
    console.log(this.cam.layers);
    this.cam?.layers.disableAll();
    this.cam?.layers.enable(2);
    this.cam?.layers.disable(0);
    this.cam?.layers.disable(1);
  }

  onAfterRender(): void {
    if (!this.cam) return;
    // we remember the current background as we want to turn it off for the layer
    const currentBackground = this.scene.background;
    // we don't want automatic color clear anymore here
    this.context.renderer.autoClearColor = false;
    console.log(this.cam);
    // if this is a Perspective Cam, update the aspect
    if (this.cam instanceof PerspectiveCamera) {
      this.context.updateAspect(this.cam.cam);
    }
    // clear background, render, and restore the background
    this.scene.background = null;
    this.context.renderer.render(this.scene, this.cam.cam);
    this.scene.background = currentBackground;
  }
}

[Rob_F (robyer1)]

Solved it, the typescript warnings about cam.cam not being a thing threw me off

Script to render a camera for Layer 1 on top, put this on the second cam for on top rendering:

import { Behaviour, Camera } from "@needle-tools/engine";
import { PerspectiveCamera } from "three";

export class CameraLayer extends Behaviour {
  private cam: Camera | null = null;

  start() {
    // getting the Camera component from the same GameObject
    this.cam = this.gameObject.getComponent(Camera);
    if (!this.cam) {
      console.warn("CameraLayer requires a Camera component");
      this.enabled = false;
    }
    // Clear current visible layers
    console.log(this.cam.layers);
    this.cam.cam.layers.disableAll();
    this.cam.cam.layers.enable(2);
    this.cam.cam.layers.enable(1);
  }

  onAfterRender(): void {
    if (!this.cam) return;
    // we remember the current background as we want to turn it off for the layer
    const currentBackground = this.scene.background;
    // we don't want automatic color clear anymore here
    this.context.renderer.autoClearColor = false;
    console.log(this.cam);
    // if this is a Perspective Cam, update the aspect
    if (this.cam.cam instanceof PerspectiveCamera) {
      this.context.updateAspect(this.cam.cam);
    }
    // clear background, render, and restore the background
    this.scene.background = null;
    this.context.renderer.render(this.scene, this.cam.cam);
    this.scene.background = currentBackground;
  }
}

Script to put on the main cam to exclude layer 1 from it:

import {
  Behaviour,
  serializable,
  showBalloonMessage,
  Camera,
} from "@needle-tools/engine";
import { PerspectiveCamera } from "three";

// Read about how to create a new component here: https://docs.needle.tools/scripting

export class ExcludeCamLayers extends Behaviour {
  private cam: Camera | null = null;
  start() {
    // getting the Camera component from the same GameObject
    this.cam = this.gameObject.getComponent(Camera);
    if (!this.cam) {
      console.warn("CameraLayer requires a Camera component");
      this.enabled = false;
    }
    // Clear current visible layers
    //this.cam.cam.layers.clear();
    this.cam.cam.layers.disableAll();
    this.cam.cam.layers.enable(0);
  }
}