"Select Polygons By Angle" is a professional tool for Blender, designed to significantly enhance the efficiency and precision of polygon selection based on angle-based criteria. The addon provides a suite of functional modes and settings aimed at optimizing workflows in fields such as Hard-Surface modeling, architectural visualization, and game asset development. Version 2.0 is a complete overhaul, with a focus on performance, visual feedback, and user-friendliness.                                                                                                                       

Key Features:

1. Angle-Based Selection:

   • The core of this mode is a flood-fill algorithm that propagates from the active polygon to adjacent ones, as long as the angle between their normals does not exceed the set threshold.
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2. Interactive Angle Preview with 3D Visualization (Core Feature):

   • Dynamic Angle Analysis: When activated (via a dedicated button or automatically), the addon displays the precise angle in real-time between the normal of the polygon under the cursor and adjacent selected polygons.
   • Automatic Threshold Calibration: On the next selection operation, the addon can automatically use this measured angle (plus a configurable tolerance) as the new Angle Threshold. This feature drastically reduces the time spent on iterative parameter tweaking.
   • Unique 3D Visualization: For maximum clarity, the addon draws auxiliary 3D elements directly in the viewport:
     • Highlights the polygon under the cursor with a semi-transparent blue color.
     • Highlights the shared edge with a selected neighbor in bright blue, instantly indicating the point of contact.
     • This feature can be disabled in the addon's preferences.
   • Contextual UI at the Cursor: The preview text changes color and icon depending on the situation: a 👁️ green eye for measuring an angle, a ⚠️ red warning if there is no selection, a ✓ grey checkmark for already selected polygons, and a ★ gold star for the active polygon. This provides instant and intuitive feedback.
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3. "Aggressive Expand" Option:

   • When activated, the flood-fill process ignores previously selected polygons as barriers, allowing the selection to "grow" through them.
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4. Directional Loop Selection:

   • Specialized for Quad Topology: Designed for fast and predictable operation on quad-based meshes.
   • Mechanics: From the active quad polygon, it initiates a loop search in horizontal and/or vertical directions.
   • Controls: Activated by the main "Enable Direction Mode" option and detailed with "Horizontal Loop" and "Vertical Loop" toggles.
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5. Selection Set Management System:

   • Smart Naming: When saving a selection, the addon automatically assigns it a name composed of the active object's name and a serial number (e.g., House_Roof_1, House_Roof_2), eliminating the need for manual renaming.
   • Safe Application: The addon will not allow applying a saved selection to a different object, preventing accidental errors. An informational message will be displayed instead.
   • Operations: Create, overwrite, delete individual or all saved sets.
   • Combined Restoration: Activate multiple saved sets (belonging to the current object) simultaneously to merge them into a single selection.
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6. User Interface and Integration:

   • Dedicated N-Panel Tab: All addon tools are conveniently grouped in their own 3D CADence tab, ensuring quick access without cluttering standard panels.
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   • Header Info Display: Dynamically displays the active mode, angle threshold, tolerance, and other key parameters.
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   • Fully Customizable Hotkeys: All addon operators are available for keymapping in Blender's preferences.
   • Organized Preferences: The addon settings are organized into logical tabs (Links, General, Keymaps), making configuration simple and straightforward.
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Benefits for Professional Use:

• Extreme Performance: Thanks to a multi-level caching system and optimized algorithms, the addon ensures absolutely smooth performance even on models with over a million polygons and hundreds of thousands of selected faces. Calculation and display operations are performed almost instantly.
• Increased Productivity: Significantly reduces time spent on routine and iterative selection tasks.
• Intuitive Feedback: The unique combination of 2D and 3D visualization makes the process completely transparent and predictable.
• Flexibility and Control: A set of modes and detailed settings allows you to adapt the tool to specific tasks.

Target Audience:

3D artists, modeling specialists (especially Hard-Surface), architects, game asset developers, and all Blender users aiming to increase efficiency and precision in their work with polygonal meshes.