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<!--
This sample uses a custom render graph to implement a basic shadow map
algorithm.
The technique works by rendering the scene in two passes. The first pass
renders the geometry in the scene with a shader that colors each pixel a shade
of gray representing how far the rendered point is from the light source. That
image, the shadow map, is rendered to a texture, and then the second (visible)
render pass samples it to determine which points in the scene are in shaodow.
-->
<!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>
Shadow Mapping
</title>
<script type="text/javascript" src="o3djs/base.js"></script>
<script type="text/javascript" id="o3dscript">
o3djs.require('o3djs.util');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.primitives');
o3djs.require('o3djs.effect');
o3djs.require('o3djs.debug');
o3djs.require('o3djs.material');
// The initClient() function runs when the page has finished loading.
window.onload = initClient;
// global variables
var g_o3dElement;
var g_client;
var g_o3d;
var g_math;
var g_pack;
var g_colorViewInfo;
var g_shadowViewInfo;
var g_shadowTexture;
var g_shadowMaterial;
var g_shadowColorEffect;
var g_shadowSampler;
var g_lightViewProjection;
var g_lightFrustumTransform;
var g_globalParams = { };
var g_viewFromLight = false;
var g_renderSurfaceSet;
var g_colorPassRenderRoot;
var g_lightWorldPos = [5, 10, 0];
var g_lightColor = [1, 1, 1, 1];
var g_eyePosition = [1, 6, 20];
var g_targetPosition = [0, 2, 0];
// constants.
var SHADOW_MAP_WIDTH = 512;
var SHADOW_MAP_HEIGHT = 512;
var g_finished = false; // for selenium testing.
/**
* Creates the client area.
*/
function initClient() {
o3djs.util.makeClients(main, 'FloatingPointTextures');
}
/**
* Initializes global variables, positions camera, draws shapes.
* @param {Array} clientElements Array of o3d object elements.
*/
function main(clientElements) {
// Init global variables.
initGlobals(clientElements);
// Set up the rendergraph.
initRenderGraph();
// Load effects, bind material parameters.
initMaterials();
// Add the shapes to the transform graph.
createShapes();
// Set up the view and projection transformations for the camera.
updateCamera();
// Init global parameters. initGlobalParams() searches all materials in order
// to bind parameters, so it must be called after initMaterials()
initGlobalParams();
// Set the view and projection transformations for the light.
updateLightMatrix();
// Create the light that gets drawn.
createLightShape();
// Execute keyPressed() when we detect a keypress on the window or
// on the o3d object.
window.document.onkeypress = keyPressed;
g_o3dElement.onkeypress = keyPressed;
g_finished = true; // for selenium testing.
}
/**
* Initializes global variables and libraries.
*/
function initGlobals(clientElements) {
g_o3dElement = clientElements[0];
g_client = g_o3dElement.client;
g_o3d = g_o3dElement.o3d;
g_math = o3djs.math;
// Create a pack to manage the objects created.
g_pack = g_client.createPack();
}
/**
* Sets up the render graph. Builds a basic view for the camera and the light
* point of view, arranges for the view from the light to be rendered to a
* texture for the shadow map. Unlike the basic render graph created by the
* the utility function o3djs.rendergraph.createBasicView, to render the shadow
* map and then render the scene, we need two subtrees of the render graph, one
* for shadow map render pass and one to draw the scene.
*/
function initRenderGraph() {
// Create the texture that will store the depth information.
g_shadowTexture = g_pack.createTexture2D(SHADOW_MAP_WIDTH,
SHADOW_MAP_HEIGHT,
g_o3d.Texture.ABGR32F,
1,
true);
var renderSurface = g_shadowTexture.getRenderSurface(0);
// Create the depth-stencil buffer required when rendering the teapot.
var depthSurface = g_pack.createDepthStencilSurface(SHADOW_MAP_WIDTH,
SHADOW_MAP_HEIGHT);
// The children of any one node in the render graph get traversed in order by
// priority. Here, we're forcing the shadow map to get rendered first by
// by giving its render root lower priority.
var shadowPassRenderRoot = g_pack.createObject('RenderNode');
shadowPassRenderRoot.priority = 0;
g_colorPassRenderRoot = g_pack.createObject('RenderNode');
g_colorPassRenderRoot.priority = 1;
shadowPassRenderRoot.parent = g_client.renderGraphRoot;
g_colorPassRenderRoot.parent = g_client.renderGraphRoot;
g_renderSurfaceSet = g_pack.createObject('RenderSurfaceSet');
g_renderSurfaceSet.renderSurface = renderSurface;
g_renderSurfaceSet.renderDepthStencilSurface = depthSurface;
g_renderSurfaceSet.parent = shadowPassRenderRoot;
// Create a render sub-graph for the shadow map generation.
g_shadowViewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_renderSurfaceSet,
[1, 1, 1, 1]);
// Create a render sub-graph for the regular pass.
g_colorViewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_colorPassRenderRoot,
[0, 0, 0, 1]);
}
/**
* Switches between the camera and light point of view.
*/
function toggleView() {
if (g_viewFromLight) {
g_shadowViewInfo.root.parent = g_renderSurfaceSet;
g_colorPassRenderRoot.parent = g_client.renderGraphRoot;
g_viewFromLight = false;
} else {
g_shadowViewInfo.root.parent = g_client.renderGraphRoot;
g_colorPassRenderRoot.parent = null;
g_viewFromLight = true;
}
}
/**
* Creates a material to be put on all shapes in the scene for the shadow pass,
* and loads effects for materials in the scene. Other materials are created
* on the fly as the shapes are created.
*/
function initMaterials() {
g_shadowMaterial = g_pack.createObject('Material');
g_shadowMaterial.drawList = g_shadowViewInfo.performanceDrawList;
var shadowEffect = g_pack.createObject('Effect');
var shadowEffectString = document.getElementById('shadowShader').text;
shadowEffect.loadFromFXString(shadowEffectString);
g_shadowMaterial.effect = shadowEffect;
shadowEffect.createUniformParameters(g_shadowMaterial);
g_shadowColorEffect = g_pack.createObject('Effect');
var colorEffectString = document.getElementById('shadowColorShader').text;
g_shadowColorEffect.loadFromFXString(colorEffectString);
g_shadowSampler = g_pack.createObject('Sampler');
g_shadowSampler.texture = g_shadowTexture;
g_shadowSampler.minFilter = g_o3d.Sampler.POINT;
g_shadowSampler.magFilter = g_o3d.Sampler.POINT;
g_shadowSampler.mipFilter = g_o3d.Sampler.POINT;
g_shadowSampler.addressModeU = g_o3d.Sampler.BORDER;
g_shadowSampler.addressModeV = g_o3d.Sampler.BORDER;
g_shadowSampler.borderColor = [1, 1, 1, 1];
}
/**
* Sets up reasonable view and projection matrices.
*/
function updateCamera() {
// Set up a perspective transformation for the projection.
g_colorViewInfo.drawContext.projection = g_math.matrix4.perspective(
g_math.degToRad(30), // 30 degree frustum.
g_o3dElement.clientWidth / g_o3dElement.clientHeight, // Aspect ratio.
1, // Near plane.
5000); // Far plane.
// Set up our view transformation to look towards the world origin where the
// cube is located.
g_colorViewInfo.drawContext.view = g_math.matrix4.lookAt(
g_eyePosition, // eye
g_targetPosition, // target
[0, 1, 0]); // up
}
/**
* Computes the view and projection matrices from the point of view of the
* light. Sets the lightViewProjection parameter so the color shader can access
* it.
*/
function updateLightMatrix() {
// The perspective projection matrix for the light.
var lightProjection = g_math.matrix4.perspective(
g_math.degToRad(45), // 45 degree fov.
SHADOW_MAP_WIDTH / SHADOW_MAP_HEIGHT, // Aspect ratio.
4, // Near plane.
20); // Far plane.
// Make the light point toward the origin
var lightView = g_math.matrix4.lookAt(
g_lightWorldPos, // light
[0, 0, 0], // target
[1, 0, 0]); // up
g_lightViewProjection = g_math.matrix4.composition(
lightProjection, lightView);
g_shadowViewInfo.drawContext.projection = lightProjection;
g_shadowViewInfo.drawContext.view = lightView;
g_globalParams.lightViewProjection.value = g_lightViewProjection;
}
/**
* Creates shapes using the primitives utility library, and adds them to the
* transform graph at the root node.
*/
function createShapes() {
// A green phong-shaded material for the cube.
var cubeMaterial = createShadowColorMaterial([0.2, 0.5, 0, 1]);
// The cube shape.
var cube = o3djs.primitives.createCube(
g_pack,
cubeMaterial,
2); // The length of each side of the cube.
// A red phong-shaded material for the sphere.
var sphereMaterial = createShadowColorMaterial([0.7, 0.2, 0.1, 1]);
// The sphere shape.
var sphere = o3djs.primitives.createSphere(
g_pack, sphereMaterial, 0.5, 50, 50);
// A blue phong-shaded material for the plane.
var planeMaterial = createShadowColorMaterial([0, 0.3, 0.5, 1]);
// The plane shape.
var plane = o3djs.primitives.createPlane(
g_pack,
planeMaterial,
20, // Width.
20, // Depth.
1, // Horizontal subdivisions.
1); // Vertical subdivisions.
// Associate to each shape, a translation vector.
var transformTable = [
{shape: cube, translation: [0, 1, 0]},
{shape: sphere, translation: [0.5, 2.5, 0]},
{shape: plane, translation: [0, 0, 0]}
];
// Add the shapes to the transform graph with the translation.
var modelRoot = g_pack.createObject('Transform');
modelRoot.parent = g_client.root;
for (var tt = 0; tt < transformTable.length; ++tt) {
var transform = g_pack.createObject('Transform');
transform.addShape(transformTable[tt].shape);
// The shadow material is bound to a DrawList in the subtree of the
// rendergraph that handles the shadow map generation, so it gets drawn in
// that render pass only.
transformTable[tt].shape.createDrawElements(g_pack, g_shadowMaterial);
transform.translate(transformTable[tt].translation);
transform.parent = modelRoot;
}
}
/**
* Creates the wireframe frustum showing the shadow map's render volume.
*/
function createLightShape() {
var inverseMatrix = g_math.matrix4.inverse(g_lightViewProjection);
// Scale and translate a cube of side length 2 to get a box
// that extends from [-1, -1, 0] to [1, 1, 1].
var shape = o3djs.lineprimitives.createLineCube(
g_pack,
o3djs.material.createConstantMaterial(g_pack,
g_colorViewInfo,
[1, 0, 0, 1]),
2,
g_math.matrix4.compose(
g_math.matrix4.translation([0, 0, 0.5]),
g_math.matrix4.scaling([1, 1, 0.5])));
g_lightFrustumTransform = g_pack.createObject('Transform');
g_lightFrustumTransform.localMatrix = inverseMatrix;
g_lightFrustumTransform.parent = g_client.root;
g_lightFrustumTransform.addShape(shape);
}
/**
* Creates a Phong-shaded, shadowed material based on the given color.
*/
function createShadowColorMaterial(baseColor) {
var material = g_pack.createObject('Material');
material.drawList = g_colorViewInfo.performanceDrawList;
material.effect = g_shadowColorEffect;
g_shadowColorEffect.createUniformParameters(material);
material.getParam('shadowMapSampler').value = g_shadowSampler;
material.getParam('ambient').value = g_math.mulScalarVector(0.1, baseColor);
material.getParam('diffuse').value = g_math.mulScalarVector(0.8, baseColor);
material.getParam('specular').value = [1, 1, 1, 1];
material.getParam('shininess').value = 80;
return material;
}
/**
* Binds params for light position, light color and the light view-projection
* matrix to all materials in the scene where they apply.
*/
function initGlobalParams() {
var paramSpec = {
'lightColor': 'ParamFloat4',
'lightWorldPos': 'ParamFloat3',
'lightViewProjection': 'ParamMatrix4'};
g_globalParams = o3djs.material.createParams(g_pack, paramSpec);
o3djs.material.bindParams(g_pack, g_globalParams);
g_globalParams.lightWorldPos.value = g_lightWorldPos;
g_globalParams.lightColor.value = g_lightColor;
}
/**
* The keyboard event handler.
*/
function keyPressed(event) {
var keyChar = String.fromCharCode(o3djs.event.getEventKeyChar(event));
keyChar = keyChar.toLowerCase();
var delta = 0.2;
switch(keyChar) {
case 'a':
moveLight([-delta, 0, 0]);
break;
case 'd':
moveLight([delta, 0, 0]);
break;
case 's':
moveLight([0, -delta, 0]);
break;
case 'w':
moveLight([0, delta, 0]);
break;
case 'i':
moveLight([0, 0, delta]);
break;
case 'o':
moveLight([0, 0, -delta]);
break;
case ' ':
toggleView();
break;
}
}
/**
* Moves the light by the given vector delta, and updates params so the light
* draws in the right spot and the shadows move.
*/
function moveLight(delta) {
g_lightWorldPos = g_math.addVector(g_lightWorldPos, delta);
g_globalParams.lightWorldPos.value = g_lightWorldPos;
updateLightMatrix();
g_lightFrustumTransform.localMatrix =
g_math.matrix4.inverse(g_lightViewProjection);
}
</script>
<script id="shadowShader" type="text/O3DShader">
/**
* This shader is for the effect applied in the first render pass, when the
* shadow map is created. The scene is rendered from the perspective of the
* light, the grayscale value of each pixel in the rendered image represents
* how far away the rendered point is from the light (the lighter, the
* farther) This image gets rendered to a texture, and that texture gets
* sampled in the second render pass, when the geometry is drawn to the
* screen.
*/
// The light's wvp matrix
float4x4 worldViewProjection : WorldViewProjection;
// Input parameters for our vertex shader.
struct VertexShaderInput {
float4 position : POSITION;
};
// Input parameters for our pixel shader.
struct PixelShaderInput {
float4 position : POSITION;
float2 depth : TEXCOORD0;
};
/**
* The vertex shader simply transforms the input vertices to screen space.
*/
PixelShaderInput vertexShaderFunction(VertexShaderInput input) {
PixelShaderInput output;
// Render from the light's perspective.
output.position = mul(input.position, worldViewProjection);
output.depth = output.position.zw;
return output;
}
/**
* The pixel shader returns a shade of gray. The lighter the shade the
* farther that fragment is from the light.
*/
float4 pixelShaderFunction(PixelShaderInput input): COLOR {
// Pixels in the shadowmap store the pixel depth from the light's
// perspective in normalized device coordinates.
float t = input.depth.x / input.depth.y;
return float4(t, t, t, 1);
}
// #o3d VertexShaderEntryPoint vertexShaderFunction
// #o3d PixelShaderEntryPoint pixelShaderFunction
// #o3d MatrixLoadOrder RowMajor
</script>
<script id="shadowColorShader" type="text/O3DShader">
/**
* This shader is for the effect applied in the second render pass when the
* shadowed shapes are drawn to the screen. In the pixel shader, the distance
* from the rendered point to the camera is compared to the distance encoded
* in the shadow map. If the distance is much greater, the rendered point is
* considered to be in shadow and is given a light coefficient of 0.
*/
float4x4 world : World;
float4x4 worldViewProjection : WorldViewProjection;
float4x4 worldInverseTranspose : WorldInverseTranspose;
float4x4 viewInverse : ViewInverse;
float4x4 lightViewProjection;
sampler shadowMapSampler;
// Parameters for the phong shader.
uniform float3 lightWorldPos;
uniform float4 lightColor;
uniform float4 ambient;
uniform float4 diffuse;
uniform float4 specular;
uniform float shininess;
// input parameters for our vertex shader
struct VertexShaderInput {
float4 position : POSITION;
float3 normal : NORMAL;
};
// input parameters for our pixel shader
struct PixelShaderInput {
float4 position : POSITION;
float4 projTextureCoords : TEXCOORD0;
float4 worldPosition : TEXCOORD1;
float3 normal : TEXCOORD2;
};
PixelShaderInput vertexShaderFunction(VertexShaderInput input) {
PixelShaderInput output;
// Transform to homogeneous clip space.
output.position = mul(input.position, worldViewProjection);
// Compute the projective texture coordinates to project the shadow map
// onto the scene.
float4x4 worldLightViewProjection = mul(world, lightViewProjection);
output.projTextureCoords = mul(input.position, worldLightViewProjection);
output.worldPosition = mul(input.position, world);
output.normal = mul(float4(input.normal, 0), worldInverseTranspose).xyz;
return output;
}
float4 pixelShaderFunction(PixelShaderInput input): COLOR {
float3 surfaceToLight = normalize(lightWorldPos - input.worldPosition);
float3 surfaceToView = normalize(viewInverse[3].xyz - input.worldPosition);
float3 normal = normalize(input.normal);
float3 halfVector = normalize(surfaceToLight + surfaceToView);
float4 litResult = lit(dot(normal, surfaceToLight),
dot(normal, halfVector), shininess);
float4 outColor = ambient;
float4 projCoords = input.projTextureCoords;
// Convert texture coords to [0, 1] range.
projCoords.xy /= projCoords.w;
projCoords.x = 0.5 * projCoords.x + 0.5;
projCoords.y = -0.5 * projCoords.y + 0.5;
// Compute the pixel depth for shadowing.
float depth = projCoords.z / projCoords.w;
// If the rednered point is farter from the light than the distance encoded
// in the shadow map, we give it a light coefficient of 0.
float light = tex2D(shadowMapSampler, projCoords.xy).r + 0.008 > depth;
// Make the illuninated area a round spotlight shape just for fun.
// Comment this line out to see just the shadows.
light *= 1 - smoothstep(0.45, 0.5, length(projCoords - float2(0.5, 0.5)));
outColor += light * lightColor *
(diffuse * litResult.y + specular * litResult.z);
return outColor;
}
// #o3d VertexShaderEntryPoint vertexShaderFunction
// #o3d PixelShaderEntryPoint pixelShaderFunction
// #o3d MatrixLoadOrder RowMajor
</script>
</head>
<body>
<h1>Shadow Maps</h1>
This sample implements a basic shadow map.
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 600px; height: 600px;"></div>
<!-- End of O3D plugin -->
Use A, S, D, W, I and O to move the light.
Press spacebar to see the shadow map.
</body>
</html>