Gravity and ground height.

js/retro/RetroArchitecture.js

@@ -1,6 +1,6 @@
 import RetroSprite from "./RetroSprite.js";
-import GeometryRect from "../geometry/GeometryRect.js";
 import RetroArchitectureTile from "./RetroArchitectureTile.js";
+import GeometryRectCollection from "../geometry/GeometryRectCollection.js";
 
 export default class RetroArchitecture
 {
@@ -24,6 +24,29 @@ export default class RetroArchitecture
         }
     }
 
+    getCollisionRects(rect)
+    {
+        let posX = Math.floor(rect.position.x / this.tileWidth) - 2;
+        let posY = Math.floor(rect.position.y / this.tileHeight) - 2;
+        let rangeX = parseInt( posX + rect.width / this.tileWidth) + 4;
+        let rangeY = parseInt(posY + rect.height / this.tileHeight) + 4;
+
+        let collection = new GeometryRectCollection();
+
+        for (let y = Math.max(0, posY); y < rangeY; y++) {
+            for (let x = Math.max(0, posX); x < rangeX; x++) {
+                if (y < this.matrix.length && x < this.matrix[y].length && this.matrix[y][x] !== null) {
+                    let intersection = this.matrix[y][x].rect.getRectIntersection(rect);
+                    if (intersection !== null) {
+                        collection.addRect(intersection);
+                    }
+                }
+            }
+        }
+
+        return collection;
+    }
+
     hasRectCollision(rect)
     {
         let posX = Math.floor(rect.position.x / this.tileWidth) - 2;

js/retro/RetroSprite.js

@@ -46,6 +46,21 @@ export default class RetroSprite
         return this.canvas.height;
     }
 
+    getFootHeight()
+    {
+        return new GeometryPoint(this.position.x, this.position.y + this.getHeight());
+    }
+
+    getPositionLeftFoot()
+    {
+        return new GeometryPoint(this.position.x - this.getWidth() * 0.5, this.position.y);
+    }
+
+    getPositionRightFoot()
+    {
+        return new GeometryPoint(this.position.x + this.getWidth() * 0.5, this.position.y);
+    }
+
     draw(context)
     {
         context.drawImage(this.canvas, this.position.x, this.position.y);