refactor to use linear spritesheet

GitOrigin-RevId: 859e5868a72922e983d5bc7f345b51b25aff10e8

Jumpy.Shared/Player.cs

@@ -1,4 +1,5 @@
 using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using Microsoft.Xna.Framework.Input;
 using System;
@@ -29,19 +30,23 @@ namespace Jumpy {
       this.texture = texture;
     }
 
+    private Rectangle Bbox(Point position) {
+      return new Rectangle(position.X - spriteWidth, position.Y - 7, spriteWidth * 2, 26);
+    }
+
     public void Update(
         GameTime time, History<GamePadState> gamePad, List<Rectangle> collisionTargets) {
       Point oldPosition = position;
       AirState oldAirState = airState;
       UpdateFromGamePad(time, gamePad);
 
-      Rectangle oldBbox = new Rectangle(oldPosition.X - spriteWidth, oldPosition.Y - 7, spriteWidth * 2, 26);
+      Rectangle oldBbox = Bbox(oldPosition);
-      Rectangle playerBbox = new Rectangle(position.X - spriteWidth, position.Y - 7, spriteWidth * 2, 26);
+      Rectangle playerBbox = Bbox(position);
       bool standingOnGround = false;
       // TODO: implement https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
       // e.g. http://members.chello.at/~easyfilter/bresenham.html
       foreach (var rect in collisionTargets) {
-        playerBbox = new Rectangle(position.X - spriteWidth, position.Y - 7, spriteWidth * 2, 26);
+        playerBbox = Bbox(position);
 
         // first we check for left-right collisions...
         if (playerBbox.Intersects(rect)) {
@@ -51,14 +56,13 @@ namespace Jumpy {
           if (oldBbox.Left >= rect.Right && playerBbox.Left < rect.Right) {
             position.X = rect.Right + spriteWidth;
           }
-          playerBbox = new Rectangle(position.X - spriteWidth, position.Y - 7, spriteWidth * 2, 26);
+          playerBbox = Bbox(position);
         }
         // after fixing that, we check for hitting our head or hitting the ground.
         if (playerBbox.Intersects(rect)) {
           if (oldPosition.Y > position.Y) {
             int diff = playerBbox.Top - rect.Bottom;
             position.Y -= diff;
-            // ySpeed *= 0.9;
           } else {
             airState = AirState.Ground;
             int diff = playerBbox.Bottom - rect.Top;
@@ -91,9 +95,10 @@ namespace Jumpy {
         Debug.AddRect(playerBbox, Color.Yellow);
       }
     }
-
+    
     // TODO: refactor input to have a virtual "which directions & buttons were being pressed"
     // instead of complicated if-statements in this function.
+    // TODO: refactor to use a state-machine.
     void UpdateFromGamePad(GameTime time, History<GamePadState> gamePad) {
       if (gamePad[0].IsButtonDown(Buttons.A) && gamePad[1].IsButtonUp(Buttons.A) &&
           airState == AirState.Ground) {
@@ -147,44 +152,44 @@ namespace Jumpy {
       position.X = Math.Min(Math.Max(position.X, 0 + spriteWidth), Camera.Width - spriteWidth);
     }
 
-    private Point spritePosition(Pose pose, GameTime time) {
+    private int spritePosition(Pose pose, GameTime time) {
       int frameNum = (time.TotalGameTime.Milliseconds / 125) % 4;
       if (frameNum == 3) {
         frameNum = 1;
       }
-
       switch (pose) {
         case Pose.Walking:
-          return new Point(spriteSize * frameNum + spriteSize * 6, 0);
+          return 6 + frameNum;
-        case Pose.Crouching:
-          return new Point(spriteSize * 7, spriteSize * 2);
         case Pose.Stretching:
-          return new Point(spriteSize * frameNum, spriteSize * 2);
+          return 18 + frameNum;
         case Pose.Jumping:
           if (jumpTime > 0.25) {
-            return new Point(spriteSize * 6, spriteSize);
+            return 15;
           } else if (jumpTime > 0) {
-            return new Point(spriteSize * 7, spriteSize);
+            return 16;
           } else {
-            return new Point(spriteSize * 8, spriteSize);
+            return 17;
           }
         case Pose.SwordSwing:
           if (swordSwingTime > 0.2) {
-            return new Point(spriteSize * 3, spriteSize * 0);
+            return 30;
           } else if (swordSwingTime > 0.1) {
-            return new Point(spriteSize * 4, spriteSize * 0);
+            return 31; 
           } else {
-            return new Point(spriteSize * 5, spriteSize * 0);
+            return 32;
           }
+        case Pose.Crouching:
+          return 25;
         case Pose.Standing:
         default:
-          return new Point(spriteSize * 7, 0);
+          return 7;
       }
     }
 
     public void Draw(GameTime time, SpriteBatch spriteBatch) {
-      Point source = spritePosition(pose, time);
+      // TODO: don't create so many "new" things that could be cached / precomputed.
-      Rectangle textureSource = new Rectangle(source.X, source.Y, spriteSize, spriteSize);
+      int index = spritePosition(pose, time);
+      Rectangle textureSource = new Rectangle(index * spriteSize, 0, spriteSize, spriteSize);
       Vector2 spriteCenter = new Vector2(spriteSize / 2, spriteSize / 2);
       SpriteEffects effect = facing == Facing.Right ?
         SpriteEffects.FlipHorizontally : SpriteEffects.None;