3D Grid Building System - Unity Tutorial | City Builder, RTS, Factorio

How to Create a Grid-Based Building System in Unity3D

Step 1: Understand the System

• The system involves using a grid and a tilemap to track available areas for building placement.
• Prefabs of buildings with defined sizes are used for placement on the grid.
• The system checks if the area under the building is clear before placing it and updates the tilemap accordingly.

Step 2: Setup Tilemap in Unity

1. Create a 3D project in Unity and import necessary packages and assets.
2. Create a plane to represent the ground and set the camera to an isometric perspective.

Step 3: Create Tilemap and Prefabs

1. In the Hierarchy, go to Create > 2D > Tilemap and select Rectangular.
2. Adjust the orientation of the grid and tilemap for correct placement.
3. Create prefabs for buildings by adding models, centering them, and adding box colliders to handle interactions.

Step 4: Develop Scripts

1. Create scripts for Grid Snapping, Object Dragging, and Building Placement.
2. Implement grid snapping by calculating mouse positions and snapping objects to the grid.
3. Handle object dragging by saving mouse click positions and updating object positions during drag.

Step 5: Implement Building Placement

1. Calculate building sizes in tiles and check for available areas on the grid.
2. Calculate the positions of building corners and convert them to tile positions on the grid.
3. Implement methods to check if a building can be placed and to mark the area as taken on the tilemap.

Step 6: Add Rotations

1. Implement rotation functionality for objects by updating vertex positions and object sizes.
2. Provide user input options to rotate objects in the scene.

Step 7: Test and Refine

1. Test the system by instantiating objects, snapping them to the grid, rotating them, and checking for valid placements.
2. Make adjustments to fit the system into your game's requirements and explore additional features like map editing and timers.

By following these steps, you can create a versatile grid-based building system in Unity3D suitable for various game genres like city builders, RTS games, and more.