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sphere.html
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sphere.html
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<html>
<head>
<title>Crosshatch experiment</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 id="shader-fs" type="x-shader/x-fragment">
#ifdef GL_ES
precision highp float;
#endif
varying vec3 vNormal;
uniform vec3 uLightingDirection;
uniform vec3 uDirectionalColor;
uniform vec3 uAmbientColor;
uniform sampler2D uSampler;
void main(void) {
float directionalLightWeighting = max(dot(normalize(vNormal), uLightingDirection), 0.0);
vec3 lightWeighting = uAmbientColor + uDirectionalColor * directionalLightWeighting;
gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
if (length(lightWeighting) < 1.00) {
if (mod(gl_FragCoord.x + gl_FragCoord.y, 10.0) == 0.0) {
gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
}
}
if (length(lightWeighting) < 0.75) {
if (mod(gl_FragCoord.x - gl_FragCoord.y, 10.0) == 0.0) {
gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
}
}
if (length(lightWeighting) < 0.50) {
if (mod(gl_FragCoord.x + gl_FragCoord.y - 5.0, 10.0) == 0.0) {
gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
}
}
if (length(lightWeighting) < 0.3465) {
if (mod(gl_FragCoord.x - gl_FragCoord.y - 5.0, 10.0) == 0.0) {
gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
}
}
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat4 uNMatrix;
varying vec3 vNormal;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vNormal = (uNMatrix * vec4(aVertexNormal, 1.0)).xyz;
}
</script>
<script type="text/javascript">
var gl;
function initGL(canvas) {
try {
gl = canvas.getContext("experimental-webgl");
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;
}
var shaderProgram;
function initShaders() {
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.vertexNormalAttribute = gl.getAttribLocation(shaderProgram, "aVertexNormal");
gl.enableVertexAttribArray(shaderProgram.vertexNormalAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
shaderProgram.nMatrixUniform = gl.getUniformLocation(shaderProgram, "uNMatrix");
shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
shaderProgram.ambientColorUniform = gl.getUniformLocation(shaderProgram, "uAmbientColor");
shaderProgram.lightingDirectionUniform = gl.getUniformLocation(shaderProgram, "uLightingDirection");
shaderProgram.directionalColorUniform = gl.getUniformLocation(shaderProgram, "uDirectionalColor");
}
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() {
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, new Float32Array(pMatrix.flatten()));
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, new Float32Array(mvMatrix.flatten()));
var normalMatrix = mvMatrix.inverse();
normalMatrix = normalMatrix.transpose();
gl.uniformMatrix4fv(shaderProgram.nMatrixUniform, false, new Float32Array(normalMatrix.flatten()));
}
var sphereVertexPositionBuffer;
var sphereVertexNormalBuffer;
var sphereVertexIndexBuffer;
function initBuffers() {
var latitudeBands = 30;
var longitudeBands = 30;
var radius = 2;
var vertexPositionData = [];
var normalData = [];
for (var latNumber = 0; latNumber <= latitudeBands; latNumber++) {
var theta = latNumber * Math.PI / latitudeBands;
var sinTheta = Math.sin(theta);
var cosTheta = Math.cos(theta);
for (var longNumber = 0; longNumber <= longitudeBands; longNumber++) {
var phi = longNumber * 2 * Math.PI / longitudeBands;
var sinPhi = Math.sin(phi);
var cosPhi = Math.cos(phi);
var x = cosPhi * sinTheta;
var y = cosTheta;
var z = sinPhi * sinTheta;
var u = 1 - (longNumber / longitudeBands);
var v = 1 - (latNumber / latitudeBands);
normalData.push(x);
normalData.push(y);
normalData.push(z);
vertexPositionData.push(radius * x);
vertexPositionData.push(radius * y);
vertexPositionData.push(radius * z);
}
}
var indexData = [];
for (var latNumber = 0; latNumber < latitudeBands; latNumber++) {
for (var longNumber = 0; longNumber < longitudeBands; longNumber++) {
var first = (latNumber * (longitudeBands + 1)) + longNumber;
var second = first + longitudeBands + 1;
indexData.push(first);
indexData.push(second);
indexData.push(first + 1);
indexData.push(second);
indexData.push(second + 1);
indexData.push(first + 1);
}
}
sphereVertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, sphereVertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(normalData), gl.STATIC_DRAW);
sphereVertexNormalBuffer.itemSize = 3;
sphereVertexNormalBuffer.numItems = normalData.length / 3;
sphereVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, sphereVertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexPositionData), gl.STATIC_DRAW);
sphereVertexPositionBuffer.itemSize = 3;
sphereVertexPositionBuffer.numItems = vertexPositionData.length / 3;
sphereVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, sphereVertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indexData), gl.STREAM_DRAW);
sphereVertexIndexBuffer.itemSize = 1;
sphereVertexIndexBuffer.numItems = indexData.length;
}
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);
gl.uniform3f(
shaderProgram.ambientColorUniform,
parseFloat(document.getElementById("ambientR").value),
parseFloat(document.getElementById("ambientG").value),
parseFloat(document.getElementById("ambientB").value)
);
var lightingDirection = Vector.create([
parseFloat(document.getElementById("lightDirectionX").value),
parseFloat(document.getElementById("lightDirectionY").value),
parseFloat(document.getElementById("lightDirectionZ").value)
]);
var adjustedLD = lightingDirection.toUnitVector().x(-1);
var flatLD = adjustedLD.flatten();
gl.uniform3fv(shaderProgram.lightingDirectionUniform, flatLD);
gl.uniform3f(
shaderProgram.directionalColorUniform,
parseFloat(document.getElementById("directionalR").value),
parseFloat(document.getElementById("directionalG").value),
parseFloat(document.getElementById("directionalB").value)
);
loadIdentity();
mvTranslate([0, 0, -6]);
gl.bindBuffer(gl.ARRAY_BUFFER, sphereVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, sphereVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, sphereVertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute, sphereVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, sphereVertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES, sphereVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
}
function tick() {
drawScene();
}
function webGLStart() {
var canvas = document.getElementById("webgl-canvas");
initGL(canvas);
initShaders();
initBuffers();
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>
</head>
<body onload="webGLStart();">
<canvas id="webgl-canvas" style="border: none;" width="500" height="500"></canvas>
<br/>
<br/>
<h2>Directional light:</h2>
<table style="border: 0; padding: 10px;">
<tr>
<td><b>Direction:</b>
<td>X: <input type="text" id="lightDirectionX" value="-1.0" />
<td>Y: <input type="text" id="lightDirectionY" value="-1.0" />
<td>Z: <input type="text" id="lightDirectionZ" value="-1.0" />
</tr>
<tr>
<td><b>Colour:</b>
<td>R: <input type="text" id="directionalR" value="0.8" />
<td>G: <input type="text" id="directionalG" value="0.8" />
<td>B: <input type="text" id="directionalB" value="0.8" />
</tr>
</table>
<h2>Ambient light:</h2>
<table style="border: 0; padding: 10px;">
<tr>
<td><b>Colour:</b>
<td>R: <input type="text" id="ambientR" value="0.2" />
<td>G: <input type="text" id="ambientG" value="0.2" />
<td>B: <input type="text" id="ambientB" value="0.2" />
</tr>
</table>
</body>
</html>