texture.html
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<html>
<head>
<title>First very simple WebGL example...</title>
<script src="./gl-matrix-min.js" type="text/javascript"></script>
<script type="text/javascript">
var projectionMatrix, modelViewMatrix;
var rotationAxis;
var shaderProgram, shaderVertexPositionAttribute
var shaderTexCoordAttribute, shaderSamplerUniform;
var shaderProjectionMatrixUniform, shaderModelViewMatrixUniform;
var duration = 5000; // ms
var currentTime = Date.now();
var okToRun = false;
var webGLTexture;
function handleTextureLoaded(gl, texture) {
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
gl.texImage2D(
gl.TEXTURE_2D,
0,
gl.RGBA,
gl.RGBA,
gl.UNSIGNED_BYTE,
texture.image);
gl.texParameteri(
gl.TEXTURE_2D,
gl.TEXTURE_MAG_FILTER,
gl.NEAREST);
gl.texParameteri(
gl.TEXTURE_2D,
gl.TEXTURE_MIN_FILTER,
gl.NEAREST);
gl.bindTexture(gl.TEXTURE_2D, null);
okToRun = true;
}
function initTexture(gl) {
webGLTexture = gl.createTexture();
webGLTexture.image = new Image();
webGLTexture.image.onload = function () {
handleTextureLoaded(gl, webGLTexture)
}
//webGLTexture.image.src = "P3D/images/webgl-logo-256.jpg";
webGLTexture.image.src = "gravatar-256.jpg";
}
function initWebGL(canvas) {
var gl = null;
var msg = "Your browser does not support WebGL, " +
"or it is not enabled by default.";
try {
gl = canvas.getContext("experimental-webgl");
}
catch (e) {
msg = "Error creating WebGL Context!: " + e.toString();
}
if (!gl) {
alert(msg);
throw new Error(msg);
}
return gl;
}
function initViewport(gl, canvas) {
gl.viewport(0, 0, canvas.width, canvas.height);
}
// Create the vertex, color, and index data for a
// multicolored cube
function createCube(gl) {
// Vertex Data
var vertexBuffer;
vertexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
var verts = [
// Front face
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,
// Back face
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,
// Top face
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
// Bottom face
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,
// Right face
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
1.0, -1.0, 1.0,
// Left face
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
-1.0, 1.0, -1.0
];
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(verts),
gl.STATIC_DRAW);
var texCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texCoordBuffer);
var textureCoords = [
// Front face
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Back face
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
// Top face
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
// Bottom face
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,
// Right face
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
// Left face
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
// Index data (defines the triangles to be drawn)
var cubeIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeIndexBuffer);
var cubeIndices = [
0, 1, 2, 0, 2, 3, // Front face
4, 5, 6, 4, 6, 7, // Back face
8, 9, 10, 8, 10, 11, // Top face
12, 13, 14, 12, 14, 15, // Bottom face
16, 17, 18, 16, 18, 19, // Right face
20, 21, 22, 20, 22, 23 // Left face
];
gl.bufferData(
gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(cubeIndices),
gl.STATIC_DRAW);
var cube = {
buffer:vertexBuffer,
texCoordBuffer:texCoordBuffer,
indices:cubeIndexBuffer,
vertSize:3,
nVerts:24,
texCoordSize:2,
nTexCoords: 24,
nIndices:36,
primtype:gl.TRIANGLES};
return cube;
}
function initMatrices(canvas) {
modelViewMatrix = mat4.create();
mat4.translate(
modelViewMatrix, modelViewMatrix, [0, 0, -8]);
// Create a project matrix with 45 degree field of view
projectionMatrix = mat4.create();
mat4.perspective(projectionMatrix, Math.PI / 4,
canvas.width / canvas.height, 1, 10000);
rotationAxis = vec3.create();
vec3.normalize(rotationAxis, [1, 1, 1]);
}
function createShader(gl, id, type) {
var shader;
var str = document.getElementById(id).text;
if (type == "fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (type == "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 initShader(gl, vertex, fragment) {
// load and compile the fragment and vertex shader
var fragmentShader = createShader(gl, fragment, "fragment");
var vertexShader = createShader(gl, vertex, "vertex");
// link them together into a new program
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
// get pointers to the shader params
shaderVertexPositionAttribute = gl.getAttribLocation(
shaderProgram, "vertexPos");
gl.enableVertexAttribArray(shaderVertexPositionAttribute);
shaderTexCoordAttribute = gl.getAttribLocation(
shaderProgram, "texCoord");
gl.enableVertexAttribArray(shaderTexCoordAttribute);
shaderProjectionMatrixUniform = gl.getUniformLocation(
shaderProgram, "projectionMatrix");
shaderModelViewMatrixUniform = gl.getUniformLocation(
shaderProgram, "modelViewMatrix");
shaderSamplerUniform = gl.getUniformLocation(
shaderProgram, "uSampler");
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
}
function draw(gl, obj) {
// clear the background (transparent)
gl.clearColor(0.0, 0.0, 0.0, 0.0);
// // clear the background (black)
// gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// set the shader to use
gl.useProgram(shaderProgram);
// connect up the shader parameters: vertex position,
// color, and projection/model matrices
// set up the buffers
gl.bindBuffer(gl.ARRAY_BUFFER, obj.buffer);
gl.vertexAttribPointer(
shaderVertexPositionAttribute,
obj.vertSize,
gl.FLOAT,
false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, obj.texCoordBuffer);
gl.vertexAttribPointer(
shaderTexCoordAttribute,
obj.texCoordSize,
gl.FLOAT,
false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.indices);
gl.uniformMatrix4fv(shaderProjectionMatrixUniform, false,
projectionMatrix);
gl.uniformMatrix4fv(shaderModelViewMatrixUniform, false,
modelViewMatrix);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, webGLTexture);
gl.uniform1i(shaderSamplerUniform, 0);
// draw the object
gl.drawElements(
obj.primtype, obj.nIndices, gl.UNSIGNED_SHORT, 0);
}
function animate() {
var now = Date.now();
var deltat = now - currentTime;
currentTime = now;
var fract = deltat / duration;
var angle = Math.PI * 2 * fract;
mat4.rotate(
modelViewMatrix,
modelViewMatrix,
angle,
rotationAxis);
}
function run(gl, cube) {
requestAnimationFrame(function() { run(gl, cube); });
if (okToRun) {
draw(gl, cube);
animate();
}
}
function startGl() {
// Get A WebGL context
var canvas = document.getElementById("cube");
var gl = initWebGL(canvas);
var obj = createCube(gl);
initViewport(gl, canvas);
initMatrices(canvas);
initShader(
gl,
"texture-vertex-shader",
"texture-fragment-shader");
initTexture(gl);
run(gl, obj);
}
</script>
<script id="texture-vertex-shader" type="x-shader/x-vertex">
attribute vec3 vertexPos;
attribute vec2 texCoord;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
varying vec2 vTexCoord;
void main(void) {
// Return the transformed and projected vertex value
gl_Position = projectionMatrix * modelViewMatrix * vec4(vertexPos, 1.0);
// Output the texture coordinate in vTexCoord
vTexCoord = texCoord;
}
</script>
<script id="texture-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
varying vec2 vTexCoord;
uniform sampler2D uSampler;
void main(void) {
// Return the pixel color: always output white
gl_FragColor = texture2D(uSampler, vec2(vTexCoord.s, vTexCoord.t));
}
</script>
</head>
<body onLoad="startGl()">
<canvas id="cube" width="500" height="500"></canvas>
</body>
</html>
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