Added variable growth factor and groundwork for victory conditions.

snake/snake.js

@@ -16,11 +16,17 @@
 
     // The starting game board.
     var startBoard;
+    var startGrowthFactor = 2;  // When we eat food, how many turns do we grow?
+    var startGFIncrease=0;      // When we eat, how much should the GF increase?
+    var targetScore = 0;        // How many pieces of food must we eat to win?
 
-    var body = new Array();
+    var body = new Array();     // Queue of body indices.
-    var headCur;
+    var headCur;                // Index of the head's current position.
-    var direction = 1;
+    var direction = 1;          // Current movement direction.
-    var foodEaten = false;
+    var foodEaten = false;      // Did we eat food this turn?
+    var growthFactor            // When we eat food, how many turns do we grow?
+    var growthCounter;          // How many remaining turns should we grow?
+    var score = 0;              // How many pieces of food have we eaten?
 
     // HTML Elements
     var canvas;
@@ -49,6 +55,8 @@
 
     function initialize(options) {
 
+        if (!options) options = {};
+
         // Store our own copy of the canvas and get a 2D graphics context.
         if (options.canvas) canvas = options.canvas;
         else canvas = document.getElementsByTagName("canvas")[0];
@@ -75,14 +83,32 @@
                 else startBoard[i] = SPACE; } }
 
         // Figure out how big each game tile is.
-        tileWidth = canvas.width / COLS;
+        tileWidth = Math.ceil(canvas.width / COLS);
-        tileHeight = canvas.height / ROWS;
+        tileHeight = Math.ceil(canvas.height / ROWS);
+        console.log("canvas.width: " + canvas.width);
+        console.log("canvas.height: " + canvas.height);
+        console.log("ROWS: " + ROWS);
+        console.log("COLS: " + COLS);
+        console.log("Tile Width: " + tileWidth);
+        console.log("Tile Height: " + tileHeight);
         
         // Mark the player as dead. This is primarily for the case where a
         // player re-initializes the board during a game in progress. It
         // causes any scheduled logic to quit without affecting out game state. 
         dead = true;
 
+        // Read in the growth factor and increase.
+        if (options.growthFactor) startGrowthFactor = options.growthFactor;
+        else startGrowthFactor = 2;
+
+        if (options.growthFactorIncrease)
+            startGFIncrease = options.growthFactorIncrease;
+        else startGFIncrease = 1;
+
+        // Check for a target score to consider this level "won."
+        if (options.targetScore) targetScore = option.targetScore;
+        else options.targetScore = 0; // 0 = no target, play indefinitely.
+        
         // Check to see if they want to use the editor or the game.
         editor = Boolean(options.editor);
 
@@ -96,7 +122,7 @@
 
             g.font = "24px sans-serif";
             g.fillStyle = "black";
-            g.fillText("Press Enter to begin.", 50, Math.floor(canvas.height/2), canvas.width - 100);
+            g.fillText("Press Space to begin.", 50, Math.floor(canvas.height/2), canvas.width - 100);
 
             if (options.fps) skipTicks = Math.ceil(1000 / options.fps);
             else skipTicks = 150; }
@@ -113,26 +139,30 @@
             
         canvas.focus(); }
 
-
     function startGame() {
         while (body.length > 0) body.pop();
         while (cmdQueue.length > 0) cmdQueue.pop();
 
-        headCur = coord2idx(Math.floor((ROWS - 1) / 2), Math.floor((COLS - 1) / 2));
         direction = 1;
         dead = pause = false;
+        score = growthCounter = 0;
         nextGameTick = (new Date).getTime() + skipTicks;
-
+        growthFactor = startGrowthFactor;
-        body.push(headCur);
+        growthFactorIncrease = startGFIncrease;
 
         // Copy over a fresh board.
         board = new Array(startBoard.length);
         for (var i = 0; i < board.length; i++) board[i] = startBoard[i];
 
         // Create a new food item and add it to the board.
-        board[newFoodLocation()] = FOOD;
+        board[randomEmptySpace()] = FOOD;
 
-        // Write the initial body segment onto the board.
+        // Find or write the initial body segment onto the board.
+        for (headCur = -1, i = 0; i < board.length; i++)
+            if (board[i] == SNAKE) headCur = i;
+        if (headCur < 0) headCur = randomEmptySpace();
+
+        body.push(headCur);
         board[headCur] = SNAKE;
 
         // Draw the board
@@ -195,13 +225,17 @@
         // 3. First check to see if we've eaten food (since it will affect
         //    collision detection for the body). This is also where growth
         //    happens via not moving the tail.
-        if (board[headCur] == FOOD) foodEaten = true;
+        if (board[headCur] == FOOD) {
+            foodEaten = true;
+            growthCounter += growthFactor;
+            growthFactor += growthFactorIncrease; }
 
         // 4. Remove the tail.
-        if (!foodEaten) {
+        if (growthCounter == 0) {
             var tailIdx = body.shift();
             board[tailIdx] = SPACE
             paintIdx(tailIdx); }
+        else growthCounter -= 1; 
 
         // 5. Detect wall and snake collisions
         if (board[headCur] == WALL || board[headCur] == SNAKE) {
@@ -214,12 +248,12 @@
         
         // 7. Create more food if needed.
         if (foodEaten) {
-            var foodLoc = newFoodLocation();
+            var foodLoc = randomEmptySpace();
             board[foodLoc] = FOOD;
             paintIdx(foodLoc); } }
 
     // Find a new location for a piece of food.
-    function newFoodLocation() {
+    function randomEmptySpace() {
         // Find all the spaces on the board that are not occupied
         var emptySpaces = new Array();
         for (var i = 0; i < board.length; i++)
@@ -236,7 +270,7 @@
         
         g.font = "24px sans-serif";
         g.fillStyle = "red";
-        g.fillText("Press Enter to retry.", 50, Math.floor(canvas.height/2), canvas.width - 100); }
+        g.fillText("Press Space to retry.", 50, Math.floor(canvas.height/2), canvas.width - 100); }
 
     function handleGameKey(ke) {
         var key = ke.keyCode ? ke.keyCode : ke.which;
@@ -245,8 +279,8 @@
         // worrying about the game becoming a black-hole for events.
         var dontCare = false;
 
-        // Enter, start a new game.
+        // Space, start a new game.
-        if (key == 13) {
+        if (key == 32) {
             dead = true;
             requestAnimationFrame(startGame); }
 
@@ -279,8 +313,8 @@
         var dontCare = false;
 
         switch (key) {
-            // Enter: place a tile.
+            // Space or Enter: place a tile.
-            case 13: board[cursorIdx] = cursorBlock; break;
+            case 32: case 13: board[cursorIdx] = cursorBlock; break;
 
             // Direction keys: move the cursor.
             case 37:  cursorIdx -= 1;    break; // Left
@@ -323,6 +357,9 @@
             board: board,
             rows: ROWS,
             cols: COLS,
+            growthFactor: startGrowthFactor,
+            growthFactorIncrease: startGFIncrease,
+            targetScore: targetScore,
             fps: Math.ceil(1000 / skipTicks)}); }
 
     // Load the editor data as a JSON string from the textarea.