alexandreservian · February 11, 2023 22:49 · May 17, 2020
diff --git a/BoxCastDrawer.cs b/BoxCastDrawer.cs
@@ -0,0 +1,138 @@
+using UnityEngine;
+
+/// <summary>
+///     A class that allows to visualize the Physics2D.BoxCast() method.
+/// </summary>
+/// <remarks>
+///     Use Draw() to visualize an already cast box,
+///     and BoxCastAndDraw() to cast a box AND visualize it at the same time.
+/// </remarks>
+
+
+public static class BoxCastDrawer
+{
+    /// <summary>
+    ///     Visualizes BoxCast with help of debug lines.
+    /// </summary>
+    /// <param name="hitInfo"> The cast result. </param>
+    /// <param name="origin"> The point in 2D space where the box originates. </param>
+    /// <param name="size"> The size of the box. </param>
+    /// <param name="angle"> The angle of the box (in degrees). </param>
+    /// <param name="direction"> A vector representing the direction of the box. </param>
+    /// <param name="distance"> The maximum distance over which to cast the box. </param>
+    public static void Draw(
+        RaycastHit2D hitInfo,
+        Vector2 origin,
+        Vector2 size,
+        float angle,
+        Vector2 direction,
+        float distance = Mathf.Infinity)
+    {
+        // Set up points to draw the cast.
+        Vector2[] originalBox = CreateOriginalBox(origin, size, angle);
+
+        Vector2 distanceVector = GetDistanceVector(distance, direction);
+        Vector2[] shiftedBox = CreateShiftedBox(originalBox, distanceVector);
+
+        // Draw the cast.
+        Color castColor = hitInfo ? Color.red : Color.green;
+        DrawBox(originalBox, castColor);
+        DrawBox(shiftedBox, castColor);
+        ConnectBoxes(originalBox, shiftedBox, Color.gray);
+
+        if (hitInfo)
+        {
+            Debug.DrawLine(hitInfo.point, hitInfo.point + (hitInfo.normal.normalized * 0.2f), Color.yellow);
+        }
+    }
+
+    /// <summary>
+    ///     Casts a box against colliders in the Scene, returning the first collider to contact with it, and visualizes it.
+    /// </summary>
+    /// <param name="origin"> The point in 2D space where the box originates. </param>
+    /// <param name="size"> The size of the box. </param>
+    /// <param name="angle"> The angle of the box (in degrees). </param>
+    /// <param name="direction"> A vector representing the direction of the box. </param>
+    /// <param name="distance"> The maximum distance over which to cast the box. </param>
+    /// <param name="layerMask"> Filter to detect Colliders only on certain layers. </param>
+    /// <param name="minDepth"> Only include objects with a Z coordinate (depth) greater than or equal to this value. </param>
+    /// <param name="maxDepth"> Only include objects with a Z coordinate (depth) less than or equal to this value. </param>
+    /// <returns>
+    ///     The cast result.
+    /// </returns>
+    public static RaycastHit2D BoxCastAndDraw(
+        Vector2 origin,
+        Vector2 size,
+        float angle,
+        Vector2 direction,
+        float distance = Mathf.Infinity,
+        int layerMask = Physics2D.AllLayers,
+        float minDepth = -Mathf.Infinity,
+        float maxDepth = Mathf.Infinity)
+    {
+        var hitInfo = Physics2D.BoxCast(origin, size, angle, direction, distance, layerMask, minDepth, maxDepth);
+        Draw(hitInfo, origin, size, angle, direction, distance);
+        return hitInfo;
+    }
+
+    private static Vector2[] CreateOriginalBox(Vector2 origin, Vector2 size, float angle)
+    {
+        float w = size.x * 0.5f;
+        float h = size.y * 0.5f;
+        Quaternion q = Quaternion.AngleAxis(angle, new Vector3(0, 0, 1));
+
+        var box = new Vector2[4]
+        {
+            new Vector2(-w, h),
+            new Vector2(w, h),
+            new Vector2(w, -h),
+            new Vector2(-w, -h),
+        };
+
+        for (int i = 0; i < 4; i++)
+        {
+            box[i] = (Vector2)(q * box[i]) + origin;
+        }
+
+        return box;
+    }
+
+    private static Vector2[] CreateShiftedBox(Vector2[] box, Vector2 distance)
+    {
+        var shiftedBox = new Vector2[4];
+        for (int i = 0; i < 4; i++)
+        {
+            shiftedBox[i] = box[i] + distance;
+        }
+
+        return shiftedBox;
+    }
+
+    private static void DrawBox(Vector2[] box, Color color)
+    {
+        Debug.DrawLine(box[0], box[1], color);
+        Debug.DrawLine(box[1], box[2], color);
+        Debug.DrawLine(box[2], box[3], color);
+        Debug.DrawLine(box[3], box[0], color);
+    }
+
+    private static void ConnectBoxes(Vector2[] firstBox, Vector2[] secondBox, Color color)
+    {
+        Debug.DrawLine(firstBox[0], secondBox[0], color);
+        Debug.DrawLine(firstBox[1], secondBox[1], color);
+        Debug.DrawLine(firstBox[2], secondBox[2], color);
+        Debug.DrawLine(firstBox[3], secondBox[3], color);
+    }
+
+    private static Vector2 GetDistanceVector(float distance, Vector2 direction)
+    {
+        if (distance == Mathf.Infinity)
+        {
+            // Draw some large distance e.g. 5 scene widths long.
+            float sceneWidth = Camera.main.orthographicSize * Camera.main.aspect * 2f;
+            distance = sceneWidth * 5f;
+        }
+
+        return direction.normalized * distance;
+    }
+}
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