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julia.html
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<!--
Copyright 2009, Google Inc.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.
-->
<!--
O3D Julia Set
This sample draws an animated julia set in real time using
the pixel shader for the computation.
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html style="width: 100%; height: 100%;">
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>
Julia Set Pixel Shader
</title>
<script type="text/javascript" src="../o3d-webgl/base.js"></script>
<script type="text/javascript" src="../o3djs/base.js"></script>
<script type="text/javascript" id="o3dscript">
o3djs.base.o3d = o3d;
o3djs.require('o3djs.webgl');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.primitives');
// Events
// Run the init() function once the page has finished loading.
// unload() when the page is unloaded.
window.onload = init;
window.onunload = unload;
// global variables
var g_o3d;
var g_math;
var g_client;
var g_o3dElement;
var g_viewInfo;
var g_pack;
var g_o3dWidth = -1;
var g_o3dHeight = -1;
var g_clock = 0.0;
var g_timeMult = 1;
var g_finished = false; // for selenium testing
var g_seedParam;
/**
* Creates the client area.
*/
function init() {
o3djs.webgl.makeClients(initStep2);
}
/**
* Initializes o3d, loads the effect, and creates the square.
* @param {Array} clientElements Array of o3d object elements.
*/
function initStep2(clientElements) {
// Initialize global variables and libraries.
g_o3dElement = clientElements[0];
g_o3d = g_o3dElement.o3d;
g_math = o3djs.math;
g_client = g_o3dElement.client;
// Create a g_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,
[0, 0, 0, 1]);
// Load shader code from DOM and use it to build the effect.
var effect = g_pack.createObject('Effect');
effect.loadFromFXString(document.getElementById('shader').value);
// Create a Material for the effect.
var myMaterial = g_pack.createObject('Material');
// Apply our effect to this material.
myMaterial.effect = effect;
// Set the material's drawList for opaque objects.
myMaterial.drawList = g_viewInfo.performanceDrawList;
// create the parameters the effect needs to the material.
effect.createUniformParameters(myMaterial);
// Create a square.
var myShape = o3djs.primitives.createPlane(g_pack, myMaterial, 1, 1, 1, 1);
// Initialize effect parameters to something reasonable
g_seedParam = myMaterial.getParam('seed');
g_seedParam.value = [0.2, 0.5];
// Put the camera somewhere where it has a good view of that square.
g_viewInfo.drawContext.view = g_math.matrix4.lookAt(
[0, 1, 0], //eye
[0, 0, 0], //target
[0, 0, -1]); //up
// Generate the projection matrix based
// on the g_o3d plugin size by calling resize().
resize();
// Now attach the square to the root of the transform graph.
g_client.root.addShape(myShape);
g_client.setRenderCallback(onrender);
g_finished = true; // for selenium testing.
}
/**
* Render callback. Walks the seed of the Julia set through
* a parametric path in the complex plane that stays
* in the neighborhood of the Mandelbrot set.
*/
function onrender(render_event) {
g_clock += render_event.elapsedTime * g_timeMult;
var t = 0.1 * g_clock;
var x = 0.6 * Math.cos(3.0 * t) - 0.3;
var y = (0.5 * x + 1.7)*(0.2 * Math.sin(7 * t));
g_seedParam.value = [x, y];
resize();
}
/**
* Generates the projection matrix based on the size of the o3d plugin and
* calculates the view-projection matrix.
*/
function resize() {
var newWidth = g_client.width;
var newHeight = g_client.height;
if (newWidth != g_o3dWidth || newHeight != g_o3dHeight) {
g_o3dWidth = newWidth;
g_o3dHeight = newHeight;
// Determine what the size of the rendered square within the client should
// be in pixels.
var side = g_o3dWidth < g_o3dHeight ?
g_o3dWidth : g_o3dHeight;
// Convert to the region of world space that must be enclosed by the
// orthographic projection.
var worldSize = g_math.divVectorScalar([g_o3dWidth, g_o3dHeight], side);
// Find a projection matrix to transform from world space to screen space.
g_viewInfo.drawContext.projection = g_math.matrix4.orthographic(
-0.5 * worldSize[0], 0.5 * worldSize[0],
-0.5 * worldSize[1], 0.5 * worldSize[1],
0.5, 1.5);
}
}
/**
* Removes any callbacks so they don't get called after the page has unloaded.
*/
function unload() {
if (g_client) {
g_client.cleanup();
}
}
</script>
</head>
<body style="width: 100%; height: 100%;">
<table style="width: 100%; height: 100%;">
<tr>
<td>
<h1>Julia Set</h1>
<p>
This sample draws an animated julia set in real time using
the pixel shader for the computation.
</p>
<table id="container" style="width: 100%; height: 80%;">
<tr>
<td height="100%">
<!-- Start of g_o3d plugin -->
<div id="o3d" style="width: 100%; height: 100%;"></div>
<!-- End of g_o3d plugin -->
</td>
</tr>
</table>
<!-- a simple way to get a multiline string -->
<textarea id="shader" name="shader" cols="80" rows="20"
style="display: none;">
// The 4x4 world view projection matrix.
uniform mat4 worldViewProjection;
// input parameters for our vertex shader
attribute vec4 position;
attribute vec2 texCoord0;
// input parameters for our pixel shader
varying vec2 texCoord;
/**
* vertexShaderMain - Multiplies position by world-view-projection matrix, and
* passes on texture coordinates scaled to put the origin in the center of the
* quad and reveal a nicely sized portion of the plane to show the julia set.
*/
void main() {
gl_Position = worldViewProjection * position;
texCoord = 4.0 * (texCoord0 - vec2(0.5, 0.5));
}
// #o3d SplitMarker
varying vec2 texCoord;
// The seed for the julia set (c in the expression z(n+1) = z(n)^2+c).
uniform vec2 seed;
/**
* pixelShaderMain - Calculates the color of the pixel by iterating on the
* formula z = z*z + seed. After some number of iterations, the magnitude of z
* determines the color.
*/
void main() {
vec2 Z = texCoord;
// Number of iterations hardcoded here. The more iterations, the crisper the
// image.
for(int i = 0; i < 10; ++i) {
Z = vec2(Z.x * Z.x - Z.y * Z.y, 2.0 * Z.x * Z.y) + seed;
// Some graphics cards and some software renderers don't appreciate large
// floating point values, so we clamp to prevent Z from getting that big.
if (i > 7) {
Z = clamp(Z, -25.0, 25.0);
}
}
gl_FragColor = (1.0 - length(Z)) * vec4(0.5, 1, 2, 1);
}
// #o3d MatrixLoadOrder RowMajor
</textarea>
</td>
</tr>
</table>
</body>
</html>