Qt Reference Documentation

snake.js Example File

demos/declarative/snake/content/snake.js
 var snake = new Array;
 var board = new Array;
 var links = new Array;
 var scheduledDirections = new Array;
 var numRows = 1;
 var numColumns = 1;
 var linkComponent = Qt.createComponent("content/Link.qml"); // XXX should resolve relative to script, not component
 var cookieComponent = Qt.createComponent("content/Cookie.qml");
 var cookie;
 var linksToGrow = 0;
 var linksToDie = 0;
 var waitForCookie = 0;
 var growType = 0;
 var skullMovementsBeforeDirectionChange = 0;

 function rand(n)
 {
   return (Math.floor(Math.random() * n));
 }

 function scheduleDirection(dir)
 {
     direction = dir;
     if(scheduledDirections[scheduledDirections.length-1]!=direction)
         scheduledDirections.push(direction);
 }

 function startNewGame()
 {
     if (state == "starting")
         return;

     if (heartbeat.running) {
         endGame();
         startNewGameTimer.running = true;
         return;
     }

     numRows = numRowsAvailable;
     numColumns = numColumnsAvailable;
     board = new Array(numRows * numColumns);
     snake = new Array;
     scheduledDirections = new Array;
     growType = 0;

     skull.z = numRows * numColumns + 1;

     for (var i = 0; i < numRows * numColumns; ++i) {
         if (i < links.length) {
             var link = links[i];
             link.spawned = false;
             link.dying = false;
         } else {
             if(linkComponent.status != Component.Ready) {
                 if(linkComponent.status == Component.Error)
                     console.log(linkComponent.errorString());
                 else
                     console.log("Still loading linkComponent");
                 continue;//TODO: Better error handling?
             }
             var link = linkComponent.createObject(playfield);
             link.z = numRows * numColumns + 1 - i;
             link.type = i == 0 ? 2 : 0;
             link.spawned = false;
             link.dying = false;
             links.push(link);
         }
     }

     head = links[0];
     snake.push(head);
     head.row = numRows/2 -1;
     head.column = numColumns/2 -1;
     head.spawned = true;

     linksToGrow = 5;
     linksToDie = 0;
     waitForCookie = 5;
     score = 0;
     startHeartbeatTimer.running = true;
     heartbeat.running = true;
 }

 function endGame()
 {
     heartbeat.running = false;
     for(var i in snake)
         snake[i].dying = true;
     if (cookie) {
         cookie.dying = true;
         cookie = 0;
     }
     lastScore = score;
     highScores.saveScore(lastScore);
 }

 function move() {

     if (!head)
         return;

     var dir = direction;

     if (scheduledDirections.length) {
         dir = scheduledDirections.shift();
     }

     if (state == "starting") {
         var turn = (dir - headDirection);
         head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
         headDirection = dir;
         return;
     }

     var row = head.row;
     var column = head.column;

     if (dir == 0) {
         row = row - 1;
     } else if (dir == 1) {
         column = column + 1
     } else if (dir == 2) {
         row = row + 1;
     } else if (dir == 3) {
         column = column - 1;
     }

     //validate the new position
     if (row < 0 || row >= numRows
         || column < 0 || column >= numColumns
         || (row == skull.row && column == skull.column)
         || !isFree(row, column)) {
         var turn = (dir - headDirection);
         head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
         headDirection = dir;
         endGame();
         return;
     }

     var newLink;
     if (linksToGrow > 0) {
         --linksToGrow;
         newLink = links[snake.length];
         newLink.spawned = false;
         newLink.rotation = snake[snake.length-1].rotation;
         newLink.type = growType;
         newLink.dying = false;
         snake.push(newLink);
     } else {
         var lastLink = snake[snake.length-1];
         board[lastLink.row * numColumns + lastLink.column] = undefined;
     }

     if (waitForCookie > 0) {
         if (--waitForCookie == 0)
             createCookie(cookie? (cookie.value+1) : 1);
     }

     for (var i = snake.length-1; i > 0; --i) {
         snake[i].row = snake[i-1].row;
         snake[i].column = snake[i-1].column;
         snake[i].rotation = snake[i-1].rotation;
     }

     if (newLink) {
         newLink.spawned = true;
     }

     // move the head
     head.row = row;
     head.column = column;
     board[row * numColumns + column] = head;

     var turn = (dir - headDirection);
     head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
     headDirection = dir;

     var value = testCookie(row, column);
     if (value > 0) {
         linksToGrow += value;
         score += value;
     }
 }

 function isFree(row, column)
 {
     return board[row * numColumns + column] == undefined;
 }

 function isHead(row, column)
 {
     return head.column == column && head.row == row;
 }

 function testCookie(row, column)
 {
     if (cookie && !cookie.dying && cookie.row == row && cookie.column == column) {
         var value = cookie.value;
         waitForCookie = value;
         growType = snake[snake.length-1].type == 1 ? 0 : 1;
         cookie.dying = true;
         cookie.z = numRows * numColumns + 2;
         return value;
     }
     return 0;
 }

 function moveSkull()
 {

     if (linksToDie > 0) {
         --linksToDie;
         var link = snake.pop();
         link.dying = true;
         board[link.row * numColumns + link.column] = undefined;
         if (score > 0)
             --score;
         if (snake.length == 0) {
             endGame();
             return;
         }
     }

     var row = skull.row;
     var column = skull.column;
     if (isHead(row, column)) {
         endGame();
         return;
     }
     row +=  skull.verticalMovement;
     column += skull.horizontalMovement;

     var attempts = 4;

     while (skullMovementsBeforeDirectionChange == 0 || row < 0 || row >= numRows
         || column < 0 || column >= numColumns
         || (!isFree(row, column) && !isHead(row, column))) {
         var d = rand(8);
         skull.verticalMovement = 0;
         skull.horizontalMovement = 0;
         skullMovementsBeforeDirectionChange = rand(20)+1;
         if (d == 0) {
             skull.verticalMovement = -1
         } else if (d == 1) {
             skull.horizontalMovement = -1;
         } else if (d == 2) {
             skull.verticalMovement = 1
         } else if (d == 3){
             skull.horizontalMovement = 1;
         } else if (cookie) {
             var rd = cookie.row - skull.row;
             var rc = cookie.column - skull.column;
             if (Math.abs(rd) > Math.abs(rc)) {
                 skull.verticalMovement = rd > 0 ? 1 : -1;
                 skullMovementsBeforeDirectionChange = Math.abs(rd);
             } else {
                 skull.horizontalMovement= rc > 0 ? 1 : -1;
                 skullMovementsBeforeDirectionChange = Math.abs(rc);
             }
         }
         row = skull.row + skull.verticalMovement;
         column = skull.column + skull.horizontalMovement;
         if (--attempts == 0)
             return;
     }

     skull.row = row;
     skull.column = column;
     --skullMovementsBeforeDirectionChange;
     var value = testCookie(row, column);
     if (value > 0)
         linksToDie += value/2;

     if (isHead(row, column))
         endGame();
 }

 function createCookie(value) {
     if (numRows * numColumns - snake.length < 10)
         return;

     var column = rand(numColumns);
     var row = rand(numRows);
     while (!isFree(row, column)) {
         column++;
         if (column == numColumns) {
             column = 0;
             row++;
             if (row == numRows)
                 row = 0;
         }
     }

     if(cookieComponent.status != Component.Ready) {
         if(cookieComponent.status == Component.Error)
             console.log(cookieComponent.errorString());
         else
             console.log("Still loading cookieComponent");
         return;//TODO: Better error handling?
     }
     cookie = cookieComponent.createObject(head.parent);
     cookie.value = value;
     cookie.row = row;
     cookie.column = column;
 }
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