Скачать или смотреть Solving 2D Raycast Issues in Unity: Overlapping Colliders and Sorting Layers

Learn how to properly use Raycasting with overlapping colliders in Unity, while considering Sorting Layers for interactive 2D game design.
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Solving 2D Raycast Issues in Unity: Overlapping Colliders and Sorting Layers

In developing a 2D game in Unity, you may encounter issues when trying to interact with game objects that overlap each other visually, leading to frustration and confusion. Specifically, you might find that the Raycast detects only the backend collider, ignoring objects that are visually in front of it due to the way Unity handles Raycasting and Sorting Layers. If you have faced this problem while working on a project, rest assured, you're not alone. Today, we will dive into why this happens and how to effectively solve it.

Understanding the Problem

In your Unity project, you've probably noticed that even if one object is visually on top of another due to its Sorting Layer, the Raycast might still recognize the collider below it. This happens because Raycasts are based on the physical positions of objects in relation to the camera, rather than their visual Layeing order. Due to this, your Raycast will seemingly ignore the topmost object if the collider behind it is enabled.

For instance, if you have a Background sprite and a Game Object sprite occupying the same position (Z-positions = 0), the Raycast will primarily recognize the Background's collider unless it is disabled.

Observations:

Sorting Layers: Do not affect the order of Raycast hits.

Z-Position: The position in 3D space matters more than visual sorting.

Collider Activation: The raycasting system prioritizes colliders based on their proximity to the camera.

What We've Tried

You may have experimented with several troubleshooting methods, such as:

Changing "Order in Layer" values

Modifying Sorting Layers

Adjusting Object positions in the hierarchy

Removing and re-adding colliders

However, these often led to only a visual change without impacting the Raycast detection.

The Solution: Get the GameObject with the Highest Sorting Layer

To effectively interact with multiple overlapping objects in 2D, you'll need to modify your Raycasting approach. Here's a guide to implementing a solution that considers the Sorting Layers while using Raycasting.

Implementing the Script

By creating a custom script, you can determine which GameObject has the highest Sorting Layer when the Raycast is fired. This will allow for accurate detection of the topmost object.

Here is a sample script that achieves this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Gather Mouse Position: The script captures the current mouse position in world coordinates.

Perform Raycast: The Physics2D.RaycastAll method checks all colliders along the ray cast from the mouse position.

Determine Highest Layer: Using a loop, the script evaluates each collider hit by the ray to find which has the highest Sorting Layer.

Interact with Object: You can then interact with the detected GameObject as needed.

Conclusion

With this approach, you can effectively manage overlapping colliders in Unity and ensure your Raycast interactions reflect the intended game design. The key takeaway is to prioritize the game's logic around layers and to customize your Raycasting functionality to account for sorting priorities. By using the script provided, you can enhance your 2D adventure game experience, allowing for smooth interactions with items and objects.

If you still have questions or need further assistance, feel free to reach out!