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graphic-o3d-samples-canvas-texturedraw.htm / htm
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<!--
Sample demonstrating drawing into a Canvas surface using a O3D texture.
-->
<!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>
O3D Canvas
</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.util');
o3djs.require('o3djs.io');
o3djs.require('o3djs.math');
o3djs.require('o3djs.primitives');
o3djs.require('o3djs.effect');
o3djs.require('o3djs.canvas');
o3djs.require('o3djs.rendergraph');
// Events
// init() once the page has finished loading.
// unload() when the page is unloaded.
window.onload = createClients;
window.onunload= unload;
// Globals
var g_o3d;
var g_math;
var g_client;
var g_pack;
var g_viewInfo;
var g_brushTexture;
var g_canvasQuad;
var g_o3dElement;
var g_finished = false; // for selenium testing.
var g_canvasWidth = 700;
var g_canvasHeight = 500;
var g_borderWidth = 50;
var g_borderHeight = 50;
var g_pluginWidth;
var g_pluginHeight;
var g_clientWidth;
var g_clientHeight;
Remove any callbacks so they don't get called after the page has unloaded.
function unload() {
if (g_client) {
g_client.cleanup();
// Clear the mouse events.
onMouseUp();
}
}
function createClients() {
o3djs.util.makeClients(init);
}
This method gets called on a mouse move event. If the mouse cursor is inside
the canvas quad then it draws a copy of the brush texture onto the canvas
surface at the mouse cursor position.
parameter: e The mouse move event object
function drawCursor(e) {
if (!g_brushTexture)
return;
var offset = {
x: e.x / g_client.width * g_clientWidth,
y: e.y / g_client.height * g_clientHeight
};
// Adjust for the top left corner of the canvas.
offset.x -= g_borderWidth;
offset.y -= g_borderHeight;
// Setting brushScale to a value other than 1 will draw a scaled copy of
// the brush bitmap onto the canvas surface. This is achieved by applying
// a scale transformation before calling drawBitmap(), and restoring the
// draw matrix immediately after.
var brushScale = 1;
if (offset.x >= 0 && offset.x < g_canvasWidth &&
offset.y >= 0 && offset.y < g_canvasHeight) {
g_canvasQuad.canvas.saveMatrix();
g_canvasQuad.canvas.scale(brushScale, brushScale);
// Note that the coordinates passed to drawBitmap get scaled by the current
// canvas drawing matrix and therefore we adjust them by the scale to get
// the bitmap to follow the mouse position.
g_canvasQuad.canvas.drawBitmap(
g_brushTexture,
(offset.x / brushScale - g_brushTexture.width * 0.5),
(offset.y / brushScale + g_brushTexture.height * 0.5));
g_canvasQuad.canvas.restoreMatrix();
g_canvasQuad.updateTexture();
}
}
Fetches the bitmap pointed to by the URL supplied by the user, creates
a O3D Texture object with it, and resets the value of g_brushTexture
to point to the newly created texture.
function changeBrushTexture() {
var textureUrl = document.getElementById('url').value;
o3djs.io.loadTexture(g_pack, textureUrl, function(texture, exception) {
// Remove the previous brush texture from the pack.
if (exception) {
alert(exception);
} else {
if (g_brushTexture) {
g_pack.removeObject(g_brushTexture);
}
g_brushTexture = texture;
}
});
}
Event handler that gets called when a mouse click takes place in the
O3D element. It registers a callback for mousemove which handles
drawing and one for mouseup which removes the mousemove event.
parameter: e The mouse down event.
function onMouseDown(e) {
o3djs.event.addEventListener(g_o3dElement, 'mousemove', drawCursor);
o3djs.event.addEventListener(g_o3dElement, 'mouseup', onMouseUp);
// Draw the cursor at the clicked spot.
drawCursor(e);
}
Event handler for mouse up. It clears the mouse move and mouse up event
handlers.
function onMouseUp() {
o3djs.event.removeEventListener(g_o3dElement, 'mousemove', drawCursor);
o3djs.event.removeEventListener(g_o3dElement, 'mouseup', onMouseUp);
}
function init(clientElements) {
// Initializes global variables and libraries.
var o3dElement = clientElements[0];
g_o3dElement = o3dElement;
g_o3d = o3dElement.o3d;
g_math = o3djs.math;
g_client = o3dElement.client;
// Store the size of the plugin, so that we can adjust coordinates in
// full-screen mode. This is necessary because we're not adjusting the aspect
// ratio; we'd rather that the canvas filled the available area, rather than
// staying a fixed size or aspect ratio.
g_clientWidth = g_o3dElement.clientWidth;
g_clientHeight = g_o3dElement.clientHeight;
// Set the texture URL.
var path = window.location.href;
var index = path.lastIndexOf('/');
path = path.substring(0, index+1) + 'assets/brush.png';
var url = document.getElementById("url").value = path;
// Creates a pack to manage our resources/assets
g_pack = g_client.createPack();
g_viewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_client.renderGraphRoot);
// Set the background color to blue.
g_viewInfo.clearBuffer.clearColor = [0.5, 0.1, 1, 1];
// Setup an orthographic projection camera.
g_viewInfo.drawContext.projection = g_math.matrix4.orthographic(
0 + 0.5,
g_client.width + 0.5,
g_client.height + 0.5,
0 + 0.5,
0.001,
1000);
g_viewInfo.drawContext.view = g_math.matrix4.lookAt(
[0, 0, 1], // Eye.
[0, 0, 0], // Target.
[0, 1, 0]); // Up.
// Creates an instance of the canvas utilities library.
var canvasLib = o3djs.canvas.create(g_pack, g_client.root, g_viewInfo);
// Create a canvas surface to draw on.
var canvasQuad =
canvasLib.createXYQuad(g_borderWidth, g_borderHeight, 0, g_canvasWidth,
g_canvasHeight, false);
canvasQuad.canvas.clear([1, 0, 0, 1]);
canvasQuad.updateTexture();
// Set the initial brush texture.
changeBrushTexture();
// Setup the events to track mouse activity.
o3djs.event.addEventListener(o3dElement, 'mousedown', onMouseDown);
g_canvasQuad = canvasQuad;
g_finished = true; // for selenium testing.
}
</script>
</head>
<body>
<h1>O3D Canvas Sample: Drawing with bitmaps</h1>
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 800px; height: 600px;"></div>
<!-- End of O3D plugin -->
<p><p>
Brush URL: <input type="text" id="url" size="100">
<input type="button" onclick="changeBrushTexture();" value="Change Brush"><BR>
<p><p>Click and drag to draw onto the red canvas surface.
</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.
