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<!--
O3D Tutorial A2
In this tutorial, we show how to perform transformations on a scene that
we have loaded.
-->
<!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>
Tutorial A2: Transformations
</title>
<!-- Include sample javascript library functions-->
<script type="text/javascript" src="o3djs/base.js"></script>
<!-- Our javascript code -->
<script type="text/javascript">
o3djs.require('o3djs.camera');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.pack');
o3djs.require('o3djs.scene');
// Events
// Run the init() function once the page has finished loading.
window.onload = init;
// global variables
var g_o3d;
var g_math;
var g_client;
var g_viewInfo;
var g_pack;
var g_keyPressDelta = 0.05;
var g_finished = false; // for selenium testing
// root node of scene
var g_sceneRoot;
Loads a scene into the transform graph.
parameter: {!o3d.Pack} pack Pack to load scene into.
parameter: {string} fileName filename of the scene.
parameter: {!o3d.Transform} parent parent node in the transform graph to
which to load the scene into.
function loadScene(pack, fileName, parent) {
// Get our full path to the scene
var scenePath = o3djs.util.getCurrentURI() + fileName;
// Load the file given the full path, and call the callback function
// when its done loading.
o3djs.scene.loadScene(g_client, pack, parent, scenePath, callback);
Our callback is called once the scene has been loaded into memory
from the web or locally.
parameter: {!o3d.Pack} pack The pack that was passed in above.
parameter: {!o3d.Transform} parent The parent that was passed in above.
parameter: {*} exception null if loading succeeded.
function callback(pack, parent, exception) {
if (exception) {
alert('Could not load: ' + fileName + '\n' + exception);
return;
}
// Get a CameraInfo (an object with a view and projection matrix)
// using our javascript library function
var cameraInfo = o3djs.camera.getViewAndProjectionFromCameras(
parent,
g_client.width,
g_client.height);
// Copy the view and projection to the draw context.
g_viewInfo.drawContext.view = cameraInfo.view;
g_viewInfo.drawContext.projection = cameraInfo.projection;
// Generate draw elements and setup material draw lists.
o3djs.pack.preparePack(pack, g_viewInfo);
g_finished = true; // for selenium testing
}
}
Creates the client area.
function init() {
o3djs.util.makeClients(initStep2);
}
Initializes O3D and loads the scene into the transform graph.
parameter: {Array} clientElements Array of o3d object elements.
function initStep2(clientElements) {
// Initializes global variables and libraries.
var o3dElement = clientElements[0];
g_o3d = o3dElement.o3d;
g_math = o3djs.math;
g_client = o3dElement.client;
// Create a pack to manage our resources/assets
g_pack = g_client.createPack();
// Create the render graph for a view.
g_viewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_client.renderGraphRoot);
// Create a transform node to act as the 'root' of the scene
g_sceneRoot = g_pack.createObject('Transform');
// Attach it to the root of the transform graph.
g_sceneRoot.parent = g_client.root;
// Load the scene into the transform graph as a child of the g_sceneRoot.
loadScene(g_pack, 'assets/teapot.tgz', g_sceneRoot);
// Execute keyPressedCallback(..) when we detect a keypress on the document.
window.document.onkeypress = keyPressedCallback;
}
Function performing the rotate action in response to a key-press.
Rotates the scene based on key pressed. (w ,s, a, d). Note that the x and
y-axis referenced here are relative to the current view of the scene.
parameter: {keyPressed} The letter pressed, in lower case.
parameter: {delta} The angle by which the scene should be rotated.
returns: true if an action was taken.
function keyPressedAction(keyPressed, delta) {
var actionTaken = false;
switch(keyPressed) {
case 'a':
g_sceneRoot.localMatrix =
g_math.mul(g_sceneRoot.localMatrix,
g_math.matrix4.rotationY(-delta));
actionTaken = true;
break;
case 'd':
g_sceneRoot.localMatrix =
g_math.mul(g_sceneRoot.localMatrix,
g_math.matrix4.rotationY(delta));
actionTaken = true;
break;
case 'w':
g_sceneRoot.localMatrix =
g_math.mul(g_sceneRoot.localMatrix,
g_math.matrix4.rotationX(-delta));
actionTaken = true;
break;
case 's':
g_sceneRoot.localMatrix =
g_math.mul(g_sceneRoot.localMatrix,
g_math.matrix4.rotationX(delta));
actionTaken = true;
break;
}
return actionTaken;
}
Callback for the keypress event.
Invokes the action to be performed for the key pressed.
parameter: {event} keyPress event passed to us by javascript.
function keyPressedCallback(event) {
var keyChar = String.fromCharCode(o3djs.event.getEventKeyChar(event));
// Just in case they have capslock on.
keyChar = keyChar.toLowerCase();
if (keyPressedAction(keyChar, g_keyPressDelta)) {
o3djs.event.cancel(event);
}
}
Resets the view of the scene by resetting its local matrix to the identity
matrix.
function resetView() {
g_sceneRoot.identity();
}
</script>
</head>
<body>
<h1>Transformations</h1>
This tutorial shows how to perform transformations on a scene that
has been loaded.
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 600px; height: 600px;"></div>
<!-- End of O3D plugin -->
<p>Use W, S, A, D to rotate.</p>
<form name="default_form" action="#" method="get">
<input type="button" value="Reset view" onclick="resetView()" />
<input type="button" value="W" id="W"
onclick="keyPressedAction('w', g_keyPressDelta);" />
<input type="button" value="S" id="S"
onclick="keyPressedAction('s', g_keyPressDelta);" />
<input type="button" value="A" id="A"
onclick="keyPressedAction('a', g_keyPressDelta);" />
<input type="button" value="D" id="D"
onclick="keyPressedAction('d', g_keyPressDelta);" />
</form>
</body>
</html>
(C) Æliens
20/2/2008
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
