initial commit

grid.gd

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+class_name Grid
+## Central grid constants and utilities for the dungeon crawler.
+## Cell size: 64x64x128 TrenchBroom units = 2x2x4 Godot units.
+
+## Size of one grid cell in world units (64 TrenchBroom units).
+const CELL_SIZE: float = 2.0
+## Half-cell offset. Cell centers sit halfway between wall planes, so with TB
+## walls on the 64-unit grid (even Godot units) cell centers land on odd units.
+const HALF_CELL: float = CELL_SIZE * 0.5
+
+
+## Snap a world position to the nearest cell center (Y axis unchanged).
+static func snap(pos: Vector3) -> Vector3:
+	return Vector3(
+		floorf(pos.x / CELL_SIZE) * CELL_SIZE + HALF_CELL,
+		pos.y,
+		floorf(pos.z / CELL_SIZE) * CELL_SIZE + HALF_CELL,
+	)
+
+
+## Convert a world position to integer cell coordinates.
+static func world_to_cell(pos: Vector3) -> Vector2i:
+	return Vector2i(
+		int(floorf(pos.x / CELL_SIZE)),
+		int(floorf(pos.z / CELL_SIZE)),
+	)