More work on object placement, removal, and rendering within scenes.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@479 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/miso/client/util/IsoUtil.java

@@ -1,5 +1,5 @@
 //
-// $Id: IsoUtil.java,v 1.8 2001/10/13 01:08:59 shaper Exp $
+// $Id: IsoUtil.java,v 1.9 2001/10/17 22:21:22 shaper Exp $
 
 package com.threerings.miso.scene.util;
 
@@ -7,7 +7,7 @@ import java.awt.*;
 import java.util.Comparator;
 
 import com.threerings.media.sprite.Sprite;
-import com.threerings.media.sprite.DirtyItemList;
+import com.threerings.media.sprite.DirtyItemList.DirtyItem;
 import com.threerings.media.tile.ObjectTile;
 import com.threerings.media.util.MathUtil;
 
@@ -20,16 +20,66 @@ import com.threerings.miso.scene.*;
  */
 public class IsoUtil
 {
-    /** The comparator used to sort dirty items in ascending render order. */
+    /** The dirty item comparator used to sort dirty items back to front. */
     public static final Comparator DIRTY_COMP = new DirtyItemComparator();
 
+    /**
+     * Returns a polygon bounding all footprint tiles of the given
+     * object tile.
+     *
+     * @param model the scene view model.
+     * @param root the polygon for the root tile at which the object
+     * is located.
+     * @param tile the object tile.
+     *
+     * @return the bounding polygon.
+     */
+    public static Polygon getObjectFootprint (
+        IsoSceneViewModel model, Polygon root, ObjectTile tile)
+    {
+	Rectangle bounds = root.getBounds();
+        int sx = bounds.x - ((tile.baseWidth - 1) * model.tilehwid);
+        int sy = bounds.y - tile.height + model.tilehei;
+
+        Polygon boundsPoly = new Polygon();
+        int rx = sx, ry = sy;
+
+        // right point
+        rx = sx + tile.width;
+        ry = bounds.y - ((tile.baseHeight - 2) * model.tilehhei);
+        boundsPoly.addPoint(rx, ry);
+
+        // bottom-middle point
+        rx = bounds.x + model.tilehwid;
+        ry = bounds.y + model.tilehei;
+        boundsPoly.addPoint(rx, ry);
+
+        // left point
+        rx = sx;
+        ry = bounds.y - ((tile.baseWidth - 2) * model.tilehhei);
+        boundsPoly.addPoint(rx, ry);
+
+        // top-middle point
+        rx += (tile.baseHeight * model.tilehwid);
+        ry -= (tile.baseHeight * model.tilehhei);
+        boundsPoly.addPoint(rx, ry);
+
+        // right point
+        rx = sx + tile.width;
+        ry = bounds.y - ((tile.baseHeight - 2) * model.tilehhei);
+        boundsPoly.addPoint(rx, ry);
+
+        return boundsPoly;
+    }
+
     /**
      * Returns a polygon bounding the given object tile display image,
      * with the bottom of the polygon shaped to conform to the known
      * object dimensions.
      *
      * @param model the scene view model.
-     * @param root the root tile at which the object is located.
+     * @param root the polygon for the root tile at which the object
+     * is located.
      * @param tile the object tile.
      *
      * @return the bounding polygon.
@@ -345,18 +395,26 @@ public class IsoUtil
     protected static final int FULL_TILE_FACTOR = 100;
 
     /**
-     * A comparator class to facilitate sorting the dirty items in
-     * ascending x- and y-coordinate order suitable for rendering in
-     * the isometric view with proper visual results.
+     * A comparator class for use in sorting the dirty sprites and
+     * objects in a scene in ascending x- and y-coordinate order
+     * suitable for rendering in the isometric view with proper visual
+     * results.
      */
-    protected static class DirtyItemComparator implements Comparator
+    public static class DirtyItemComparator implements Comparator
     {
         public int compare (Object a, Object b)
         {
-            DirtyItemList.DirtyItem da = (DirtyItemList.DirtyItem)a;
-            DirtyItemList.DirtyItem db = (DirtyItemList.DirtyItem)b;
+            DirtyItem da = (DirtyItem)a;
+            DirtyItem db = (DirtyItem)b;
 
-            if (da.y <= db.y && da.x <= db.x) {
+            // check whether right edge of a overlaps with left edge of b
+            int comp = getRightOverlap(da, db);
+            if (comp != 0) {
+                return comp;
+            }
+
+            // determine ordering based purely on coordinates
+            if (da.x <= db.x && da.y <= db.y) {
                 return -1;
             }
 
@@ -367,5 +425,52 @@ public class IsoUtil
         {
 	    return (obj == this);
         }
+
+        /**
+         * Checks the right edge of <code>da</code> to see whether it
+         * overlaps with the left edge of <code>db</code>.
+         *
+         * @return -1 if <code>da</code> should be rendered behind
+         * <code>db</code>, 0 if the right edge of <code>da</code>
+         * does not overlap with <code>db</code>, and 1 if
+         * <code>da</code> should be rendered in front of
+         * <code>db</code>.
+         */
+        protected int getRightOverlap (DirtyItem da, DirtyItem db)
+        {
+            int ax = da.x, bx = db.x;
+            int ay = da.y, by = db.y;
+
+            // get da's rightmost corner coordinate
+            if (da.obj instanceof ObjectTile) {
+                ay -= (((ObjectTile)da.obj).baseHeight - 1);
+            }
+
+            // get db's leftmost corner coordinate
+            if (db.obj instanceof ObjectTile) {
+                bx -= (((ObjectTile)db.obj).baseWidth - 1);
+            }
+
+            // Log.info("getOverlap [ax=" + ax + ", ay=" + ay +
+            // ", bx=" + bx + ", by=" + by + "].");
+
+            if (ax > bx && ay < by) {
+                // we most certainly don't overlap
+                return 0;
+            }
+
+
+            // calculate inequality constant for db's leftmost corner
+            int k = (bx + by);
+
+            // we need to determine whether to render da in front of
+            // db, so we check whether da's rightmost corner is above
+            // or below db's leftmost corner.
+            if (ay <= k - ax) {
+                return -1;
+            } else {
+                return 1;
+            }
+        }
     }
 }