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<!--
Copyright 2009, Google Inc.
All rights reserved.
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modification, are permitted provided that the following conditions are
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notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-->
<!--
Checker Game Example
This sample demonstates usage of primitive functions and simple 3d animation techniques.
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>
3D Checkers Game
</title>
<script type="text/javascript" src="o3djs/base.js"></script>
<!-- Our javascript code -->
<script type="text/javascript" id="o3dscript">
o3djs.require('o3djs.util');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.material');
o3djs.require('o3djs.primitives');
o3djs.require('o3djs.arcball');
o3djs.require('o3djs.picking');
o3djs.require('o3djs.math');
o3djs.require('o3djs.quaternions');
// global variables
var g_o3dElement;
var g_client;
var g_o3d;
var g_math;
var g_quaternions;
var g_pack;
var g_viewInfo;
var g_sceneRoot;
var g_eyeView;
var g_cubeShape;
var g_cylinderShape;
var g_prismShape;
var g_material;
var g_aball;
var g_thisRot;
var g_lastRot;
var g_zoomFactor;
var g_dragging = false;
var g_treeInfo; // information about the transform graph.
var g_statusInfoElem;
// Animation globals.
var g_flashTimer;
var g_moveTimer;
var g_moveDuration;
var g_oldFlashTimer;
// Checkers globals.
var g_board;
var g_boardSize;
var g_boardSquare;
var g_boardHeight;
var g_pieceHeight;
var g_selectedPiece;
var g_selectedSquare;
var g_player;
var g_canJump;
/**
* Creates the client area.
*/
function initClient() {
window.g_finished = false; // for selenium testing.
// Runs the sample in V8. Comment out this line to run it in the browser
// JavaScript engine, for example if you want to debug it.
o3djs.util.setMainEngine(o3djs.util.Engine.V8);
o3djs.util.makeClients(main);
}
/**
* Initializes global variables, positions camera, draws the 3D chart.
* @param {Array} clientElements Array of o3d object elements.
*/
function main(clientElements) {
// Init global variables.
initGlobals(clientElements);
// Set up the view and projection transformations.
initContext();
// Add the checkers board to the transform hierarchy.
createCheckersBoard();
// Register mouse events handlers
o3djs.event.addEventListener(g_o3dElement, 'mousedown', startDragging);
o3djs.event.addEventListener(g_o3dElement, 'mousemove', drag);
o3djs.event.addEventListener(g_o3dElement, 'mouseup', stopDragging);
o3djs.event.addEventListener(g_o3dElement, 'wheel', scrollMe);
// Set the rendering callback
g_client.setRenderCallback(onrender);
window.g_finished = true; // for selenium testing.
}
/**
* Initializes global variables and libraries.
*/
function initGlobals(clientElements) {
// init o3d globals.
g_o3dElement = clientElements[0];
window.g_client = g_client = g_o3dElement.client;
g_o3d = g_o3dElement.o3d;
g_math = o3djs.math;
g_quaternions = o3djs.quaternions;
// Create an arcball.
g_aball = o3djs.arcball.create(g_client.width, g_client.height);
// Create a pack to manage the objects created.
g_pack = g_client.createPack();
// Create a transform node to act as the 'root' of the scene.
// Attach it to the root of the transform graph.
g_sceneRoot = g_pack.createObject('Transform');
g_sceneRoot.parent = g_client.root;
// Create the render graph for the view.
var clearColor = [.98, .98, .98, 1];
g_viewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_client.renderGraphRoot,
clearColor);
// Create a material for the objects rendered.
g_material = o3djs.material.createBasicMaterial(
g_pack,
g_viewInfo,
[1, 1, 1, 1]);
// Initialize checkers piece and square data.
g_boardSize = 8;
g_boardSquare = 10;
g_boardHeight = g_boardSquare / 5;
g_pieceHeight = g_boardHeight * 0.75;
g_selectedPiece = null;
g_selectedSquare = null;
// Create a cube shape for the board squares.
g_cubeShape = o3djs.primitives.createCube(
g_pack,
g_material,
1);
// Create a cylinder shape for the checkers pieces.
g_cylinderShape = o3djs.primitives.createCylinder(
g_pack,
g_material,
g_boardSquare / 2 - 1, // Radius.
g_pieceHeight, // Depth.
100, // Number of subdivisions.
1);
// use an extruded poligon to create a 'crown' for the king piece.
var polygon = [[0, 0], [1, 0], [1.5, 1.5], [0.5, 0.5],
[0, 2], [-0.5, 0.5], [-1.5, 1.5], [-1, 0]];
// use the 'prism' primitive for the crown.
g_prismShape = o3djs.primitives.createPrism(
g_pack,
g_material,
polygon, // The profile polygon to be extruded.
1); // The depth of the extrusion.
// Get the status element.
g_statusInfoElem = o3djs.util.getElementById('statusInfo');
// Initialize player data.
g_player = 1; // red player starts first.
g_canJump = false;
// Initialize various animation globals.
g_flashTimer = 0;
g_moveTimer = 0;
g_moveDuration = 1.3;
g_oldFlashTimer = 0;
}
/**
* Initialize the original view of the scene.
*/
function initContext() {
g_eyeView = [-5, 120, 100];
g_zoomFactor = 1.03;
g_dragging = false;
g_sceneRoot.identity();
g_lastRot = g_math.matrix4.identity();
g_thisRot = g_math.matrix4.identity();
// Set up a perspective transformation for the projection.
g_viewInfo.drawContext.projection = g_math.matrix4.perspective(
Math.PI * 40 / 180, // 30 degree frustum.
g_o3dElement.clientWidth / g_o3dElement.clientHeight, // Aspect ratio.
1, // Near plane.
10000); // Far plane.
// Set up our view transformation to look towards the axes origin.
g_viewInfo.drawContext.view = g_math.matrix4.lookAt(
g_eyeView, // eye
[0, 0, 0], // target
[0, 1, 0]); // up
}
/**
* Creates a Coord object used to hold a set of 2D coordinates.
*
* @private
* @constructor
* @param {number} x X coordinate.
* @param {number} y Y coordinate.
*/
function Coord(x, y) {
this.x = x;
this.y = y;
}
/**
* Creates a BoardInfo object to hold board information.
*
* @private
* @constructor
* @param {number} x X coordinate on the checkers board.
* @param {number} y Y coordinate on the checkers board.
*/
function BoardInfo(x, y) {
this.x = x;
this.y = y;
this.square = null;
this.type = 0;
this.pieceParent = null;
this.piece = null;
this.king = false;
}
/**
* Returns the initial settings for a given position on the board.
*
* @param {number} x X coordinate on the checkers board.
* @param {number} y Y coordinate on the checkers board.
* @return {number} 0 = no piece, 1 = red piece, -1 = white piece
*/
function getSquarePiece(x, y) {
// if bad coordinates, no piece.
if (x >= g_boardSize || x < 0 || y >= g_boardSize || y < 0)
return 0;
// if on rows 3 and 4 or on a white square - no piece.
if (y == 3 || y == 4 || ((x + y) % 2 == 1))
return 0;
// if on rows 0-2 it is a red piece, otherwise white piece.
if (0 <= y && y < 3) return 1;
if (5 <= y && y < 8) return -1;
// Any not covered case.
return 0;
}
/**
* Creates the checkers board.
*/
function createCheckersBoard() {
g_board = [];
// Create a checker board (black at 0,0).
for (var i = 0; i < g_boardSize; i += 1) { // columns.
g_board[i] = [];
for (var j = 0; j < g_boardSize; j += 1) { // rows.
// create the transform for the board squares.
var square = g_pack.createObject('Transform');
square.parent = g_sceneRoot;
square.addShape(g_cubeShape);
// translate and scale the squares correctly relative to origin.
var offset = g_boardSquare * (1 - g_boardSize) / 2;
square.translate(offset + g_boardSquare * i ,
0, -(offset + g_boardSquare * j));
square.scale(g_boardSquare, g_boardHeight, g_boardSquare);
// set the square color.
var isBlack = (i + j) % 2 == 0 ? true : false;
var squareColor = isBlack ?
[0.15, 0.15, 0.15, 1] : [0.85, 0.85, 0.75, 1];
square.createParam('diffuse', 'ParamFloat4').value = squareColor;
// add this square and its info to the board.
g_board[i][j] = new BoardInfo(i, j);
g_board[i][j].square = square;
// create the piece for this square and update the board position.
// skip if the square has no piece.
var pieceType = getSquarePiece(i, j);
if (pieceType == 0)
continue;
// create a parent transform for this piece.
var pieceParent = g_pack.createObject('Transform');
pieceParent.parent = g_sceneRoot;
// create the checkers piece.
var piece = g_pack.createObject('Transform');
piece.parent = pieceParent;
piece.addShape(g_cylinderShape);
// place the piece on the correct location on the board.
pieceParent.translate(0, (g_pieceHeight + g_boardHeight) / 2, 0);
pieceParent.translate(offset + g_boardSquare * i ,
0, -(offset + g_boardSquare * j));
// pick the piece color (red or white).
piece.createParam('diffuse', 'ParamFloat4').value =
getPieceColor(pieceType);
// update the board info to include this piece.
g_board[i][j].piece = piece;
g_board[i][j].pieceParent = pieceParent;
g_board[i][j].type = pieceType;
}
}
// Update our tree info.
updateTreeInfo();
// update status.
updateStatus('Game starting... RED moves first.', true);
}
/**
* Checks if a piece has become a 'king' piece and updates it.
*
* @param {number} x X coordinate on the checkers board.
* @param {number} y Y coordinate on the checkers board.
*/
function checkAndUpdateKing(x, y) {
// if the piece is not on the king row, nothing to do.
if ( y > 0 && y < g_boardSize - 1 ) return;
// ignore if no piece or the piece is already king
var selSquare = g_board[x][y];
if (!selSquare.piece || selSquare.king) return;
// change the king piece color.
selSquare.king = true;
// create the crown shape.
var crown = g_pack.createObject('Transform');
crown.parent = selSquare.piece;
crown.addShape(g_prismShape);
var crownSize = g_pieceHeight;
crown.scale(crownSize, crownSize, crownSize);
crown.translate(0, g_pieceHeight / 2, 0);
crown.createParam('diffuse', 'ParamFloat4').value = [1, 1, 0, 0];
}
/**
* Updates the transform tree info.
*/
function updateTreeInfo() {
if (!g_treeInfo) {
g_treeInfo = o3djs.picking.createTransformInfo(g_client.root, null);
}
g_treeInfo.update();
}
/**
* Check if a player selection is a jump.
*
* @param {BoardInfo} piece The board info for the piece.
* @param {BoardInfo} square The board info for the landing square.
* @return {boolean} true if this is a jump.
*/
function isJump(piece, square) {
return (Math.abs(piece.x - square.x) == 2 &&
Math.abs(piece.y - square.y) == 2 );
}
function isLegalMove(piece, square) {
var orig = new Coord(piece.x, piece.y);
var dest = new Coord(square.x, square.y);
// it must be this player's turn to make a move.
if (piece.type != g_player) return false;
// the destination must be un-occupied.
if (square.type != 0 ) return false;
// must move diagonally.
var diag = new Coord(dest.x - orig.x, dest.y - orig.y);
if (Math.abs(diag.x) != Math.abs(diag.y)) return false;
// cannot move more than 2.
if (Math.abs(diag.x) > 2) return false;
// make sure the piece is moved in the 'forward' direction
// unless this is a 'king' piece.
if (!piece.king && g_player * diag.y < 0) return false;
// if a jump check if valid.
if (Math.abs(diag.x) == 2) {
var jumpType = g_board[(orig.x + dest.x)/2][(orig.y + dest.y)/2].type;
if (jumpType == piece.type || jumpType == 0)
return false;
}
return true;
}
/**
* Update the status message.
*
* @param {string} statusMsg The message to display.
* @param {boolean} opt_hidePlayer Prefix the status with the name of the player.
*/
function updateStatus(statusMsg, opt_hidePlayer) {
var status = (g_player == 1) ? 'RED: ' : 'WHITE: ';
g_statusInfoElem.innerHTML = (opt_hidePlayer ? '' : status) + statusMsg;
}
/**
* Check if a valid boad coordinate.
*
* @param {number} x X coordinate on the checkers board.
* @param {number} y Y coordinate on the checkers board.
* @return {boolean} True if a valid coordinate.
*/
function isValidCoord(x, y) {
if ( x < 0 || x >= g_boardSize ) return false;
if ( y < 0 || y >= g_boardSize ) return false;
return true;
}
/**
* Check if a piece has a valid sliding move.
*
* @param {!BoardInfo} piece The board info for the piece.
* @return {boolean} True if the piece can slide.
*/
function pieceCanSlide(piece) {
var x = piece.x;
var y = piece.y;
for (var i = -1; i <= 1; i += 2) {
for (var j = -1; j <= 1; j += 2) {
if (isValidCoord(x + i, y + j))
if (isLegalMove(piece, g_board[x + i][y + j]))
return true;
}
}
return false;
}
/**
* Check if a piece has a valid jumping move.
*
* @param {!BoardInfo} piece The board info for the piece.
* @return {boolean} True if the piece can jump.
*/
function pieceCanJump(piece) {
var x = piece.x;
var y = piece.y;
for (var i = -2; i <= 2; i += 4) {
for (var j = -2; j <= 2; j += 4) {
if (isValidCoord(x + i, y + j))
if (isLegalMove(piece, g_board[x + i][y + j]))
return true;
}
}
return false;
}
/**
* Check if the current player has any moves available.
*
* @return {boolean} True if the player can move.
*/
function currentPlayerCanMove() {
var canSlide = false;
for (var x = 0; x < g_boardSize; x += 1) {
for (var y = 0; y < g_boardSize; y += 1) {
var sel = g_board[x][y];
if (sel.piece == null) continue;
// if jump set the canJump variable and return.
g_canJump = pieceCanJump(sel);
if (g_canJump) return true;
if (pieceCanSlide(sel)) {
canSlide = true;
}
}
}
return canSlide;
}
/**
* Check if a forced jump is required for the current player.
*
* @return {boolean} True if a jump is required.
*/
function checkForcedJump() {
for (var x = 0; x < g_boardSize; x += 1) {
for (var y = 0; y < g_boardSize; y += 1) {
var sel = g_board[x][y];
if (sel.piece && pieceCanJump(sel)) {
g_forcedJump = true;
return true;
}
}
}
g_forcedJump = false;
return false;
}
/**
* Check if the game is over.
*
* @return {boolean} True if the game is over.
*/
function isGameOver() {
// the game is over when a player has no pieces left
// or it cannot make a valid move.
if (!currentPlayerCanMove()) {
var statusStr = (g_player == 1) ? 'White Won!' : 'Red Won!';
updateStatus(statusStr, true);
return true;
}
return false;
}
/**
* Detect a mouse click an element of the checkers board.
*
* @param {event} e event.
*/
function detectSelection(e) {
var worldRay = o3djs.picking.clientPositionToWorldRay(e.x,
e.y,
g_viewInfo.drawContext,
g_client.width,
g_client.height);
// check if we picked any objects.
var pickInfo = g_treeInfo.pick(worldRay);
if (pickInfo) {
// get the parent transform of this object.
var pickTrans = pickInfo.shapeInfo.parent.transform;
// check if a board square or a piece.
for (var x = 0; x < g_boardSize; x += 1) {
for (var y = 0; y < g_boardSize; y += 1) {
if (pickTrans === g_board[x][y].piece) {
// do not select another player's piece.
if (g_player != g_board[x][y].type) return;
// if a previous piece selection, clear it.
if (g_selectedPiece) {
g_selectedPiece.piece.getParam('diffuse').value =
getPieceColor(g_selectedPiece.type);
}
// check if a forced jump.
if (g_canJump) {
if (!pieceCanJump(g_board[x][y])) {
updateStatus('Must jump, incorrect piece!');
return;
}
}
SelectPiece(x, y);
return;
} else if (pickTrans === g_board[x][y].square) {
// selected the landing square if a piece move is pending.
if (g_selectedPiece) {
// check if a forced jump.
if (g_canJump && !isJump(g_selectedPiece, g_board[x][y])) {
updateStatus('Must jump!');
return;
}
// check if a legal move, then move the piece.
if (isLegalMove(g_selectedPiece, g_board[x][y])) {
SelectSquare(x, y);
} else {
updateStatus('Illegal move!');
}
}
return;
}
}
}
}
}
/**
* Select a piece on the checkers board.
*/
function SelectPiece(x, y) {
g_selectedPiece = g_board[x][y];
// update status message.
updateStatus('Selected piece at (' + x + ',' + y + ')');
}
/**
* Select a square on the checkers board.
*/
function SelectSquare(x, y) {
updateStatus('Moving piece from (' + g_selectedPiece.x + ',' +
g_selectedPiece.y + ') to (' + x + ',' + y + ')');
g_selectedSquare = g_board[x][y];
g_moveTimer = 0;
}
/**
* Return the color for the given piece type.
*
* @param {number} type Type of the checkers piece.
* @return {Array} Array representing the color.
*/
function getPieceColor(type) {
return (type == 1) ? [1, 0.15, 0.15, 1] : [1, 1, 1, 1];
}
/**
* Called every frame.
* @param {o3d.RenderEvent} renderEvent Rendering Information.
*/
function onrender(renderEvent) {
g_flashTimer += renderEvent.elapsedTime;
g_flashTimer = g_flashTimer % 0.5;
if (g_selectedPiece) {
var origColor = getPieceColor(g_selectedPiece.type);
// flash highlight the selected piece as long as selected.
if (g_oldFlashTimer > g_flashTimer ) {
g_selectedPiece.piece.getParam('diffuse').value = [0.6, 1, 1, 1];
} else if (g_flashTimer >= 0.25 && g_oldFlashTimer < 0.25) {
g_selectedPiece.piece.getParam('diffuse').value = origColor;
}
// check if we selected a square to move the piece.
if (g_selectedSquare) {
moveSelectedPiece(renderEvent.elapsedTime);
}
}
g_oldFlashTimer = g_flashTimer;
}
/**
* Slides or jumps the selected piece.
* This method is used to simulate the animation of the moving piece.
* @param {number} elapsedTime The elapsed time in seconds since the last call.
*/
function moveSelectedPiece(elapsedTime) {
g_moveTimer += elapsedTime;
// animate the piece one iteration at the time.
var lerp = g_moveTimer / g_moveDuration;
// get the board coordinates of the curent and future position.
var x0 = g_selectedPiece.x;
var y0 = g_selectedPiece.y;
var x1 = g_selectedSquare.x;
var y1 = g_selectedSquare.y;
// get the coordinates relative to axis origin.
var offset = g_boardSquare * (1 - g_boardSize) / 2;
var xc0 = offset + g_boardSquare * x0;
var zc0 = -(offset + g_boardSquare * y0);
var xc1 = offset + g_boardSquare * x1;
var zc1 = -(offset + g_boardSquare * y1);
var yc = (g_pieceHeight + g_boardHeight) / 2;
// Our piece's position and rotation.
var px;
var pz;
var jump = 0;
var rotation = 0;
var done = false;
if (lerp < 1) {
// check if this is a jump.
if (isJump(g_selectedPiece, g_selectedSquare)) {
// compute the jump height.
jump = Math.sin(Math.PI * lerp) * g_pieceHeight * 13;
// simulate a spinning of the jumping piece.
rotation = -lerp * 4 * Math.PI;
}
px = xc0 + (xc1 - xc0) * lerp;
pz = zc0 + (zc1 - zc0) * lerp;
} else {
// done with the move.
px = xc1;
pz = zc1;
done = true;
}
// move the piece to the new position.
var pieceParent = g_board[x0][y0].pieceParent;
pieceParent.identity();
pieceParent.translate(px, yc + jump, pz);
// spin the piece
g_selectedPiece.piece.identity();
g_selectedPiece.piece.rotateX(rotation);
if (done) {
// stop flashing - restore the original color.
var origColor = getPieceColor(g_selectedPiece.type);
g_selectedPiece.piece.getParam('diffuse').value = origColor;
// if a jump destroy the jumped piece.
var wasJump = isJump(g_selectedPiece, g_selectedSquare);
if (wasJump) {
var xj = (x0 + x1)/2;
var yj = (y0 + y1)/2;
g_board[xj][yj].type = 0;
g_board[xj][yj].pieceParent.parent = null;
g_board[xj][yj].pieceParent = null;
g_board[xj][yj].piece = null;
}
// the new square has a new piece.
g_board[x1][y1].type = g_selectedPiece.type;
g_board[x1][y1].king = g_selectedPiece.king;
g_board[x1][y1].piece = g_selectedPiece.piece;
g_board[x1][y1].pieceParent = g_selectedPiece.pieceParent;
// the original square is now empty.
g_board[x0][y0].type = 0;
g_board[x0][y0].piece = null;
g_board[x0][y0].pieceParent = null;
// check if the moved piece became king.
checkAndUpdateKing(x1, y1);
g_selectedPiece = null;
g_selectedSquare = null;
g_moveTimer = 0;
// update the tree info.
updateTreeInfo();
// check if current player can jump again.
if (wasJump && pieceCanJump(g_board[x1][y1])) {
g_selectedPiece = g_board[x1][y1];
updateStatus('Must jump again ...');
} else {
// this player is done, switch players.
g_player = -g_player;
// check if game over; also checks if the current player must jump.
if (!isGameOver()) {
updateStatus(g_canJump ? 'Must jump...' : 'Next turn...');
}
}
}
}
/**
* Zooms the scene in / out by changing the viewpoint.
* @param {number} zoom zooming factor.
*/
function ZoomInOut(zoom) {
for (i = 0; i < g_eyeView.length; i += 1) {
g_eyeView[i] = g_eyeView[i] / zoom;
}
g_viewInfo.drawContext.view = g_math.matrix4.lookAt(
g_eyeView, // eye.
[0, 0, 0], // target.
[0, 1, 0]); // up.
}
/**
* Start mouse dragging.
* @param {event} e event.
*/
function startDragging(e) {
detectSelection(e);
g_lastRot = g_thisRot;
g_aball.click([e.x, e.y]);
g_dragging = true;
}
/**
* Use the arcball to rotate the scene.
* Computes the rotation matrix.
* @param {event} e event.
*/
function drag(e) {
if (g_dragging) {
var rotationQuat = g_aball.drag([e.x, e.y]);
var rot_mat = g_quaternions.quaternionToRotation(rotationQuat);
g_thisRot = g_math.matrix4.mul(g_lastRot, rot_mat);
var m = g_sceneRoot.localMatrix;
g_math.matrix4.setUpper3x3(m, g_thisRot);
g_sceneRoot.localMatrix = m;
}
}
/**
* Stop dragging.
* @param {event} e event.
*/
function stopDragging(e) {
g_dragging = false;
}
/**
* Using the mouse wheel zoom in and out of the scene.
* @param {event} e event.
*/
function scrollMe(e) {
var zoom = (e.deltaY < 0) ? 1 / g_zoomFactor : g_zoomFactor;
ZoomInOut(zoom);
g_client.render();
}
</script>
</head>
<body onload="initClient()">
<h2>3D Checkers Game</h2>
<div style="font-size:10;"><span id="statusInfo"></span></div>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 600px; height: 600px;"></div>
<!-- End of O3D plugin -->
</body>
</html>
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