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teapot-sobel-depth.html
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<html>
<head>
<title>Depth edge detection teapot</title>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="sylvester.js"></script>
<script type="text/javascript" src="glUtils.js"></script>
<script type="text/javascript" src="webgl.debug.js"></script>
<script id="depth-fs" type="x-shader/x-fragment">
#ifdef GL_ES
precision highp float;
#endif
varying float vDepth;
void main(void) {
float depth = vDepth / 100.0;
gl_FragColor = vec4(depth, mod(depth * 256.0, 1.0), mod(depth * 65536.0, 1.0), mod(depth * 16777216.0, 1.0));
}
</script>
<script id="matrix-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat4 uNMatrix;
varying float vDepth;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vDepth = gl_Position.z;
}
</script>
<script id="direct-texture-fs" type="x-shader/x-fragment">
#ifdef GL_ES
precision highp float;
#endif
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
void main(void) {
gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
}
</script>
<script id="flat-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec2 aTextureCoord;
varying vec2 vTextureCoord;
void main(void) {
gl_Position = vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;
}
</script>
<script id="sobel-fs" type="x-shader/x-fragment">
#ifdef GL_ES
precision highp float;
#endif
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
void main(void) {
mat3 xKernel = mat3(
-1.0, 0, 1.0,
-2.0, 0, 2.0,
-1.0, 0, 1.0
);
mat3 yKernel = mat3(
-1.0, -2.0, -1.0,
0.0, 0.0, 0.0,
1.0, 2.0, 1.0
);
float xSlope = 0.0;
float ySlope = 0.0;
for (float i=-1.0; i<=1.0; i++) {
for (float j=-1.0; j<=1.0; j++) {
vec4 vDepth = texture2D(uSampler, vec2(vTextureCoord.s + i/512.0, vTextureCoord.t + j/512.0));
float depth = vDepth.r + vDepth.g / 256.0 + vDepth.b / 65536.0 + vDepth.a / 16777216.0;
xSlope += depth * xKernel[int(i)+1][int(j)+1];
ySlope += depth * yKernel[int(i)+1][int(j)+1];
}
}
float magnitude = length(vec2(xSlope, ySlope));
if (magnitude > 0.045) {
gl_FragColor += vec4(0.0, 0.0, 0.0, 1.0);
} else {
gl_FragColor += vec4(1.0, 1.0, 1.0, 1.0);
}
}
</script>
<script type="text/javascript">
var gl;
function initGL(canvas) {
try {
gl = canvas.getContext("experimental-webgl");
gl = WebGLDebugUtils.makeDebugContext(gl);
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
} catch(e) {
}
if (!gl) {
alert("Could not initialise WebGL, sorry :-(");
}
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var str = "";
var k = shaderScript.firstChild;
while (k) {
if (k.nodeType == 3) {
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.type == "x-shader/x-vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
} else {
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
function createProgram(fsId, vsId) {
var normalsFragmentShader = getShader(gl, fsId);
var vertexShader = getShader(gl, vsId);
var program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, normalsFragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
alert("Could not initialise shaders " + vsId + ", " + fsId + gl.getProgramInfoLog(program));
}
gl.useProgram(program);
program.vertexPositionAttribute = gl.getAttribLocation(program, "aVertexPosition");
program.vertexNormalAttribute = gl.getAttribLocation(program, "aVertexNormal");
program.textureCoordAttribute = gl.getAttribLocation(program, "aTextureCoord");
program.pMatrixUniform = gl.getUniformLocation(program, "uPMatrix");
program.mvMatrixUniform = gl.getUniformLocation(program, "uMVMatrix");
program.nMatrixUniform = gl.getUniformLocation(program, "uNMatrix");
program.samplerUniform = gl.getUniformLocation(program, "uSampler");
program.materialShininessUniform = gl.getUniformLocation(program, "uMaterialShininess");
program.ambientColorUniform = gl.getUniformLocation(program, "uAmbientColor");
program.pointLightingLocationUniform = gl.getUniformLocation(program, "uPointLightingLocation");
program.pointLightingSpecularColorUniform = gl.getUniformLocation(program, "uPointLightingSpecularColor");
program.pointLightingDiffuseColorUniform = gl.getUniformLocation(program, "uPointLightingDiffuseColor");
return program;
}
var depthProgram;
var sobelProgram;
var directTextureProgram;
function initShaders() {
depthProgram = createProgram("depth-fs", "matrix-vs");
sobelProgram = createProgram("sobel-fs", "flat-vs");
directTextureProgram = createProgram("direct-texture-fs", "flat-vs");
}
var mvMatrix;
var mvMatrixStack = [];
function mvPushMatrix(m) {
if (m) {
mvMatrixStack.push(m.dup());
mvMatrix = m.dup();
} else {
mvMatrixStack.push(mvMatrix.dup());
}
}
function mvPopMatrix() {
if (mvMatrixStack.length == 0) {
throw "Invalid popMatrix!";
}
mvMatrix = mvMatrixStack.pop();
return mvMatrix;
}
function loadIdentity() {
mvMatrix = Matrix.I(4);
}
function multMatrix(m) {
mvMatrix = mvMatrix.x(m);
}
function mvTranslate(v) {
var m = Matrix.Translation($V([v[0], v[1], v[2]])).ensure4x4();
multMatrix(m);
}
function createRotationMatrix(angle, v) {
var arad = angle * Math.PI / 180.0;
return Matrix.Rotation(arad, $V([v[0], v[1], v[2]])).ensure4x4();
}
function mvRotate(angle, v) {
multMatrix(createRotationMatrix(angle, v));
}
var pMatrix;
function perspective(fovy, aspect, znear, zfar) {
pMatrix = makePerspective(fovy, aspect, znear, zfar);
}
function setMatrixUniforms(program) {
gl.uniformMatrix4fv(program.pMatrixUniform, false, new Float32Array(pMatrix.flatten()));
gl.uniformMatrix4fv(program.mvMatrixUniform, false, new Float32Array(mvMatrix.flatten()));
var normalMatrix = mvMatrix.inverse();
normalMatrix = normalMatrix.transpose();
gl.uniformMatrix4fv(program.nMatrixUniform, false, new Float32Array(normalMatrix.flatten()));
}
var teapotVertexPositionBuffer;
var teapotVertexNormalBuffer;
var teapotVertexTextureCoordBuffer;
var teapotVertexIndexBuffer;
function handleLoadedTeapot(teapotData) {
teapotVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(teapotData.vertexNormals), gl.STATIC_DRAW);
teapotVertexNormalBuffer.itemSize = 3;
teapotVertexNormalBuffer.numItems = teapotData.vertexNormals.length / 3;
teapotVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexTextureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(teapotData.vertexTextureCoords), gl.STATIC_DRAW);
teapotVertexTextureCoordBuffer.itemSize = 2;
teapotVertexTextureCoordBuffer.numItems = teapotData.vertexTextureCoords.length / 2;
teapotVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(teapotData.vertexPositions), gl.STATIC_DRAW);
teapotVertexPositionBuffer.itemSize = 3;
teapotVertexPositionBuffer.numItems = teapotData.vertexPositions.length / 3;
teapotVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, teapotVertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(teapotData.indices), gl.STREAM_DRAW);
teapotVertexIndexBuffer.itemSize = 1;
teapotVertexIndexBuffer.numItems = teapotData.indices.length;
document.getElementById("loadingtext").textContent = "";
}
function loadTeapot() {
var request = new XMLHttpRequest();
request.open("GET", "Teapot.json");
request.onreadystatechange = function() {
if (request.readyState == 4) {
handleLoadedTeapot(JSON.parse(request.responseText));
}
}
request.send();
}
var directTextureVertexPositionBuffer;
var directTextureVertexTextureCoordBuffer;
function initBuffers() {
directTextureVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, directTextureVertexPositionBuffer);
var vertices = [
1.0, 1.0,
-1.0, 1.0,
1.0, -1.0,
-1.0, -1.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
directTextureVertexPositionBuffer.itemSize = 2;
directTextureVertexPositionBuffer.numItems = 4;
directTextureVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, directTextureVertexTextureCoordBuffer);
var textureCoords = [
1.0, 1.0,
0.0, 1.0,
1.0, 0.0,
0.0, 0.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
directTextureVertexTextureCoordBuffer.itemSize = 2;
directTextureVertexTextureCoordBuffer.numItems = 4;
}
function createRTTFrameBuffer() {
framebuffer = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
framebuffer.width = 512;
framebuffer.height = 512;
framebuffer.texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, framebuffer.texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
gl.generateMipmap(gl.TEXTURE_2D);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, framebuffer.width, framebuffer.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
var renderbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, renderbuffer);
gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, framebuffer.width, framebuffer.height);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, framebuffer.texture, 0);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, renderbuffer);
gl.bindTexture(gl.TEXTURE_2D, null);
gl.bindRenderbuffer(gl.RENDERBUFFER, null);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
return framebuffer;
}
var depthFramebuffer;
function initRTTFramebuffers() {
depthFramebuffer = createRTTFrameBuffer();
}
var teapotAngle = 180;
function drawScene() {
// Render the depth of the spinning teapot scene to a texture.
gl.bindFramebuffer(gl.FRAMEBUFFER, depthFramebuffer);
gl.useProgram(depthProgram);
gl.viewport(0, 0, depthFramebuffer.width, depthFramebuffer.height);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
if (teapotVertexPositionBuffer == null || teapotVertexNormalBuffer == null || teapotVertexTextureCoordBuffer == null || teapotVertexIndexBuffer == null) {
return;
}
perspective(45, depthFramebuffer.width / depthFramebuffer.height, 0.1, 100.0);
loadIdentity();
mvTranslate([0, 0, -40]);
mvRotate(23.4, [1, 0, -1]);
mvRotate(teapotAngle, [0, 1, 0]);
gl.bindBuffer(gl.ARRAY_BUFFER, teapotVertexPositionBuffer);
gl.enableVertexAttribArray(depthProgram.vertexPositionAttribute);
gl.vertexAttribPointer(depthProgram.vertexPositionAttribute, teapotVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, teapotVertexIndexBuffer);
setMatrixUniforms(depthProgram);
gl.drawElements(gl.TRIANGLES, teapotVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
var program;
if (document.getElementById("id_render_type").value == "depth") {
// The viewer wants to see the depth as a colour map, so just blat the texture onto the canvas.
program = directTextureProgram;
} else {
// The viewer wants to see the edges, so use the a program that does nothing in the vertex shader
// and runs a sobel-filter program in the fragment shader
program = sobelProgram;
}
gl.useProgram(program);
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, depthFramebuffer.texture);
gl.uniform1i(program.samplerUniform, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, directTextureVertexPositionBuffer);
gl.enableVertexAttribArray(program.vertexPositionAttribute);
gl.vertexAttribPointer(program.vertexPositionAttribute, directTextureVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, directTextureVertexTextureCoordBuffer);
gl.enableVertexAttribArray(program.textureCoordAttribute);
gl.vertexAttribPointer(program.textureCoordAttribute, directTextureVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms(program);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, directTextureVertexPositionBuffer.numItems);
}
var lastTime = 0;
function animate() {
var timeNow = new Date().getTime();
if (lastTime != 0) {
var elapsed = timeNow - lastTime;
teapotAngle += 0.05 * elapsed;
}
lastTime = timeNow;
}
function tick() {
drawScene();
animate();
}
function webGLStart() {
var canvas = document.getElementById("teapot-canvas");
initGL(canvas);
initShaders();
initBuffers();
initRTTFramebuffers();
loadTeapot();
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.clearDepth(1.0);
gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
setInterval(tick, 15);
}
</script>
<style type="text/css">
#loadingtext {
position:absolute;
top:250px;
left:150px;
font-size:2em;
color: white;
}
</style>
</head>
<body onload="webGLStart();">
<canvas id="teapot-canvas" style="border: none;" width="500" height="500"></canvas>
<div id="loadingtext">Loading world...</div>
<br/>
Render:
<select id="id_render_type">
<option value="depth">Depth</option>
<option selected value="edges">Edges (Sobel-filtered)</option>
</select>
</body>
</html>