SerhiiStudio / ShadowCaster2DGenerator

Automatic generator for ShadowCaster2D components based on sprite alpha channels. Suitable for creating complex 2D shadows in the Universal Render Pipeline.

ShadowCaster2D Generator for Unity

Automatic generator for ShadowCaster2D components based on sprite alpha channels. Suitable for creating complex 2D shadows in the Universal Render Pipeline.

Links:

• Key Features
• Usage
• Structure
• Notes
• Author

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🔧 Key Features

• Generates ShadowCaster2D components based on sprite outlines.
• Determines shadow shape considering transparency (alpha channel).
• Saves created objects as prefabs to a specified folder.
• Cleans up temporary objects from the scene.
• Visualizes contours in the editor via Gizmos.
• Enhanced Efficiency & Advanced Automation:
  • Dramatically boosts productivity by transforming 1-5 hours of manual effort into a swift 30-second to 2-minute automated process.
  • Utilizes sophisticated algorithms for alpha channel-based pixel traversal and contour mask creation, followed by precise contour tracing and coordinate conversion. This solution was developed with AI guidance, demonstrating an innovative approach to complex automation challenges.

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📦 Usage

1. Add the ShadowCaster2DMaker component to a GameObject in your scene.
2. Populate the sprites list, select the folder, and specify the targetFolderName.
3. Call GenerateShadows() from the Inspector or via an editor script.
4. If needed, call ClearMadeGameObjects() to remove temporary objects.

To generate shadows without saving them to a folder, activate the DoNotSaveToFolder flag in the Advanced menu.
⚠️ Notes:

• If you enable DoNotSaveToFolder during generation and then disable it, the generated objects won't be saved to the folder, and ClearMadeGameObjects will no longer have a reference to them.
• ClearMadeGameObjects will remove all objects created in the current session from the scene, provided it still holds references to them (see above).

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📁 Structure

ShadowCaster2DMaker.cs

A component for generating shadows from sprites in the editor.

Fields:

• Sprite[] sprites — An array of sprites for generation.
• DefaultAsset folder — The root folder for saving the results.
• string targetFolderName — The name of the subfolder for the output.
• Advanced:
  • bool doNotSaveToFolder — A flag to prevent saving as prefabs.

Methods:

• GenerateShadows() — The main method for generating shadows.
• ClearMadeGameObjects() — Cleans up created objects from the scene (if they were saved as prefabs or cleared manually).

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MakePoints.cs

A helper static class for processing sprites.

Key Steps:

1. GetPixels — Retrieves pixels from the sprite's texture.
2. GetAlphaMask — Creates a 2D mask of opaque pixels.
3. ExtractContourMask — Extracts the contour based on the mask.
4. ExtractContourPoints — Forms a sequence of points along the contour.
5. SimplifyPoints — Simplifies the geometry (removes redundant points).
6. ConvertToLocalPoints — Converts points to local coordinates.

Result:

A Vector3[] array of points for the m_ShapePath field of the ShadowCaster2D component.

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VisualizeShadow.cs

A Gizmos component for displaying the shadow contour in the editor.

Fields:

• ShadowCaster2D shadowCaster — A reference to the caster.

Features:

• Draws Gizmos lines between the points of the m_ShapePath private field of the ShadowCaster2D component.

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SaveToFolder.cs

A helper static class for saving shadows as prefabs.

Fields:

• const string PREFAB_EXTENSION - The string ".prefab" used to construct the path before saving.

Features:

• Determines the save path.
• Saves a GameObject as a .prefab file.

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⚠️ Notes

• The scripts use reflection to access private fields and methods of ShadowCaster2D and ShadowUtility.
• Tested with Unity 2022.3.35f1 and URP 14.0.11, may not work or might cause errors with other Unity versions.
• Works only in the Unity Editor, as it utilizes UnityEditor, Undo, EditorUtility, etc.
• It is assumed that Universal Render Pipeline (URP) is already integrated into the project.

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👨‍💻 Author

SerhiiStudio
Unity Tools & Games
GitHub: SerhiiStudio