shadow-map.html

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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="../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.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_colorEffect;
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.webgl.makeClients(main, 'FloatingPointTextures', true);
}


/**
 * 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;

  //toggleView();

  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() {
  // 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;

  g_colorPassRenderRoot.parent = g_client.renderGraphRoot;

  // 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);

  shadowPassRenderRoot.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() {
  var colorVertexShader = document.getElementById('colorVertexShader').text;
  var colorPixelShader = document.getElementById('colorPixelShader').text;

  g_colorEffect = g_pack.createObject('Effect');
  g_colorEffect.loadVertexShaderFromString(colorVertexShader);
  g_colorEffect.loadPixelShaderFromString(colorPixelShader);

  var shadowVertexShader = document.getElementById('shadowVertexShader').text;
  var shadowPixelShader = document.getElementById('shadowPixelShader').text;

  g_shadowMaterial = g_pack.createObject('Material');
  g_shadowMaterial.drawList = g_shadowViewInfo.performanceDrawList;

  var shadowEffect = g_pack.createObject('Effect');
  shadowEffect.loadVertexShaderFromString(shadowVertexShader);
  shadowEffect.loadPixelShaderFromString(shadowPixelShader);

  g_shadowMaterial.effect = shadowEffect;
  shadowEffect.createUniformParameters(g_shadowMaterial);

  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;
  // Note: The o3d-plugin used BORDER as address mode, but that is not available
  // in WebGL so use WRAP instead.
  g_shadowSampler.addressModeU = g_o3d.Sampler.WRAP;
  g_shadowSampler.addressModeV = g_o3d.Sampler.WRAP;
  //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.

  var adjustedProjection =
          [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 2, 0], [0, 0, -1, 1]];
      o3d.Transform.compose(
          adjustedProjection, lightProjection, adjustedProjection);

  // 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 = createColorMaterial([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 = createColorMaterial([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 = createColorMaterial([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 createColorMaterial(baseColor) {
  var material = g_pack.createObject('Material');
  material.drawList = g_colorViewInfo.performanceDrawList;

  material.effect = g_colorEffect;
  g_colorEffect.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 = 20;

  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="shadowVertexShader" type="text/glsl">
  /**
   * 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.
   */
  attribute vec4 position;
  uniform mat4 worldViewProjection;

  varying vec4 vposition;

  void main() {
    vposition = worldViewProjection * position;
    gl_Position = vposition;
  }
</script>
<script id="shadowPixelShader" type="text/glsl">
  varying vec4 vposition;

  void main() {
    vec4 color;
    vec3 q = vposition.xyz / vposition.w;

    float depth = 0.5*(q.z + 1.0);
    color.r = fract(16777216.0 * depth);
    color.g = fract(65536.0 * depth);
    color.b = fract(256.0 * depth);
    color.a = depth;

    gl_FragColor = color;
  }
</script>


<script id="colorVertexShader" type="text/glsl">
  attribute vec4 position;
  attribute vec3 normal;

  uniform mat4 worldViewProjection;
  uniform mat4 world;
  uniform mat4 worldInverseTranspose;
  uniform mat4 lightViewProjection;

  varying vec4 vposition;
  varying vec3 vnormal;
  varying vec4 vprojTextureCoords;
  varying vec4 vworldPosition;

  /**
   * The vertex shader simply transforms the input vertices to screen space.
   */
  void main() {
    vworldPosition = world * position;
    vnormal = vec3(worldInverseTranspose * vec4(normal, 0));
    vposition = worldViewProjection * position;
    vprojTextureCoords = lightViewProjection * world * position;
    gl_Position = vposition;
  }
</script>
<script id="colorPixelShader" type="text/glsl">
  uniform vec4 ambient;
  uniform vec4 diffuse;
  uniform vec4 specular;
  uniform float shininess;

  varying vec4 vposition;
  varying vec4 vworldPosition;
  varying vec3 vnormal;
  varying vec4 vprojTextureCoords;

  uniform sampler2D shadowMapSampler;

  uniform vec3 lightWorldPos;
  uniform mat4 viewInverse;

  vec3 lighting(vec3 position, vec3 normal, vec4 pigment, vec4 specular, float shininess) {
    vec3 l = normalize(vec3(lightWorldPos) - position);  // Toward light.
    vec3 n = normalize(normal);                          // Normal.
    vec3 v = normalize(vec3(viewInverse * vec4(0,0,0,1)) - position); // Toward eye.
    vec3 r = normalize(-reflect(v, n));

    return clamp(dot(n,l), 0.0, 1.0) * diffuse.rgb +
        0.2 * specular.rgb * pow(max(dot(l, r), 0.0), shininess);
  }

  void main() {
    vec3 outColor = ambient.rgb;
    vec4 projCoords = vprojTextureCoords;

    // Convert texture coords to [0, 1] range.
    projCoords /= projCoords.w;
    projCoords = 0.5 * projCoords + 0.5;

    float depth = projCoords.z;
    float light;

    // If the rednered point is farther from the light than the distance encoded
    // in the shadow map, we give it a light coefficient of 0.
    vec4 color = texture2D(shadowMapSampler, projCoords.xy);

    light = (color.a +
             color.b / 256.0 +
             color.g / 65536.0 +
             color.r / 16777216.0) + 0.008 > depth ? 1.0 : 0.0;

    // Make the illuninated area a round spotlight shape just for fun.
    // Comment this line out to see just the shadows.
    light *= 1.0 - smoothstep(0.45, 0.5,
        length(projCoords.xy - vec2(0.5, 0.5)));

    outColor += light * lighting(
        vec3(vworldPosition),
        vnormal,
        diffuse,
        specular,
        shininess);

    gl_FragColor = vec4(outColor, 1.0);
  }
</script>


</head>
<body>
<h1>Shadow Maps</h1>
This sample implements a basic shadow map.
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 800px; 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>