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<!--
O3D Tutorial
In this tutorial, we load and display a scene in O3D and then
apply a procedural texture to it.
-->
<!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>
Applying a Procedural Texture to a scene
</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.rendergraph');
o3djs.require('o3djs.pack');
o3djs.require('o3djs.camera');
o3djs.require('o3djs.scene');
// Events
// init() once the page has finished loading.
window.onload = init;
// global variables
var g_o3d;
var g_client;
var g_viewInfo;
var g_pack;
var g_finished = false; // for selenium testing
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;
// Add our checker pattern
createCheckerBoard(pack, 'Material__26');
// Generate draw elements and setup material draw lists.
o3djs.pack.preparePack(pack, g_viewInfo);
g_finished = true; // for selenium testing.
}
}
In order to apply the texture you must know the material name which you wish
to change. The bulk of the calculation takes place in the shader itself.
Alternatively, you could change the first or all the materials if you don't
know the material name.
parameter: {!o3d.Pack} pack The pack the scene was loaded into.
parameter: {string} materialName Name of material you wish to turn into checkers.
function createCheckerBoard(pack, materialName) {
var effectString = document.getElementById('checkerShader').value;
var effect = g_pack.createObject('Effect');
effect.loadFromFXString(effectString);
var materials = pack.getObjects(materialName, 'o3d.Material');
for (var m = 0; m < materials.length; m++) {
var material = materials[m];
// Set the material to use the checker effect.
material.effect = effect;
// Create any parameters the effect needs on the material.
effect.createUniformParameters(material);
}
}
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_client = o3dElement.client;
// Creates 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);
// Creates a transform to put our data on.
var myDataRoot = g_pack.createObject('Transform');
// Connects our root to the client's root.
myDataRoot.parent = g_client.root;
// Load the scene into the transform graph as a child myDataRoot
loadScene(g_pack, 'assets/teapot.tgz', myDataRoot);
}
</script>
</head>
<body>
<h1>Applying a Procedural Texture to a scene</h1>
This tutorial shows how to apply a procedural texture to a scene.
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 600px; height: 600px;"></div>
<!-- End of O3D plugin -->
<!-- Don't render the textarea -->
<div style="display:none">
<textarea id="checkerShader" name="checkerShader" cols="80" rows="20">
// The 4x4 world view projection matrix.
float4x4 worldViewProjection : WORLDVIEWPROJECTION;
// input parameters for our vertex shader
struct a2v {
float4 position : POSITION;
float3 normal : NORMAL;
float2 texcoord : TEXCOORD0;
};
// input parameters for our pixel shader
struct v2f {
float4 position : POSITION;
float4 col : COLOR;
float2 texcoord : TEXCOORD0;
};
// function for getting the checker pattern
float4 checker(float2 uv) {
float checkSize = 4;
float fmodResult = fmod(floor(checkSize * uv.x) + floor(checkSize * uv.y),
2.0);
if (fmodResult < 1) {
return float4(0, 1, 1, 1);
} else {
return float4(1, 0, 1, 1);
}
}
Our vertex shader. In the vertex shader, we calculate the lighting.
Then we'll combine it with our checker pattern in the pixel shader.
v2f vertexShaderFunction(a2v input) {
v2f output;
output.position = mul(input.position, worldViewProjection);
lightVector - light vector
normal - normal vector
We put the light such that it illuminates our model.
float4 diffuseColor = float4(1, 1, 1, 1);
float3 lightPos = float3(1000, -1000, 1000);
float3 lightVector = normalize(lightPos - input.position.xyz);
float3 normal = normalize(input.normal);
float4 diffuse = dot(normal, lightVector) * diffuseColor;
output.col = diffuse;
output.texcoord = input.texcoord;
return output;
}
Our pixel shader. We take the lighting color we got from the vertex sahder
and combine it with our checker pattern.
float4 pixelShaderFunction(v2f input): COLOR {
float4 check = checker(input.texcoord);
float4 color = input.col * check;
return color;
}
// Here we tell our effect file *which* functions are
// our vertex and pixel shaders.
// #o3d VertexShaderEntryPoint vertexShaderFunction
// #o3d PixelShaderEntryPoint pixelShaderFunction
// #o3d MatrixLoadOrder RowMajor
</textarea>
</div>
</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.
