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<!--
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(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="o3djs/base.js"></script>
<script type="text/javascript" id="o3d">
o3djs.require('o3djs.util');
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.util.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.
float4x4 worldViewProjection : WORLDVIEWPROJECTION;
// The seed for the julia set (c in the expression z(n+1) = z(n)^2+c).
float2 seed;
// input parameters for our vertex shader
struct VertexShaderInput {
float4 position : POSITION;
float2 texCoord : TEXCOORD0;
};
// input parameters for our pixel shader
// also the output parameters for our vertex shader
struct PixelShaderInput {
float4 position : POSITION;
float2 texCoord : TEXCOORD0;
};
/**
* 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.
*/
PixelShaderInput vertexShaderMain(VertexShaderInput input) {
PixelShaderInput output;
output.position = mul(input.position, worldViewProjection);
output.texCoord = 4.0 * (input.texCoord - float2(0.5, 0.5));
return output;
}
/**
* 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.
*/
float4 pixelShaderMain(PixelShaderInput input) : COLOR {
float2 Z = input.texCoord;
// Number of iterations hardcoded here. The more iterations, the crisper the
// image.
for(int i = 0; i < 10; ++i) {
Z = float2(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, 25);
}
}
return (1 - length(Z)) * float4(0.5, 1, 2, 1);
}
// Here we tell our effect file *which* functions are
// our vertex and pixel shaders.
// #o3d VertexShaderEntryPoint vertexShaderMain
// #o3d PixelShaderEntryPoint pixelShaderMain
// #o3d MatrixLoadOrder RowMajor
</textarea>
</td>
</tr>
</table>
</body>
</html>
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