runelite-api: Optimize getClickbox

- Use the pre-calculated center/extreme xyz fields for the aabb
 - use modelToCanvas and reduce indirection
 - Use a specialized union that only does axis-aligned rectangles
     instead of the Area class
 - Use a specialized intersection that only does convex polygons, again
     to avoid Area

runelite-api/src/test/java/net/runelite/api/geometry/RectangleUnionTest.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2019 Abex
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.runelite.api.geometry;
+
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.Shape;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import javax.imageio.ImageIO;
+import lombok.extern.slf4j.Slf4j;
+import org.junit.Assert;
+
+@Slf4j
+public class RectangleUnionTest
+{
+	private static final int ITERATIONS = 100;
+	private static final int WIDTH = 1000;
+	private static final int MAX_RECTS = 50;
+
+	// @Test
+	public void test() throws IOException
+	{
+		for (int count = 1; count < MAX_RECTS; count++)
+		{
+			for (int r = 0; r < ITERATIONS; r++)
+			{
+				Random rand = new Random(count << 16 | r);
+				String id = count + "rects_iteration" + r;
+				log.info(id);
+				BufferedImage wanted = new BufferedImage(WIDTH, WIDTH, BufferedImage.TYPE_BYTE_BINARY);
+				BufferedImage got = new BufferedImage(WIDTH, WIDTH, BufferedImage.TYPE_BYTE_BINARY);
+
+				Graphics2D wg = wanted.createGraphics();
+				wg.setColor(Color.WHITE);
+				Graphics2D gg = got.createGraphics();
+				gg.setColor(Color.WHITE);
+
+				List<RectangleUnion.Rectangle> rects = new ArrayList<>(count);
+
+				for (int i = 0; i < count; i++)
+				{
+					int x1, y1, x2, y2;
+
+					do
+					{
+						x1 = rand.nextInt(WIDTH);
+						x2 = rand.nextInt(WIDTH);
+					}
+					while (x1 >= x2);
+
+					do
+					{
+						y1 = rand.nextInt(WIDTH);
+						y2 = rand.nextInt(WIDTH);
+					}
+					while (y1 >= y2);
+
+					RectangleUnion.Rectangle rect = new RectangleUnion.Rectangle(x1, y1, x2, y2);
+					log.trace("{}", rect);
+					rects.add(rect);
+
+					wg.fillRect(x1, y1, x2 - x1, y2 - y1);
+				}
+
+				Shape union = RectangleUnion.union(rects);
+
+				gg.fill(union);
+
+				loop:
+				for (int x = 0; x < WIDTH; x++)
+				{
+					for (int y = 0; y < WIDTH; y++)
+					{
+						if (wanted.getRGB(x, y) != got.getRGB(x, y))
+						{
+							File tmp = new File(System.getProperty("java.io.tmpdir"));
+							ImageIO.write(wanted, "png", new File(tmp, id + "_wanted.png"));
+							ImageIO.write(got, "png", new File(tmp, id + "_got.png"));
+
+							Assert.fail(id);
+							break loop;
+						}
+					}
+				}
+			}
+		}
+	}
+}