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webgl-data-texture-3x2.html
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<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - Textures - Data Texture 3x2</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<div class="description">
A 3x2 texture<br/>
</div>
<canvas id="canvas"></canvas>
</body>
<!-- vertex shader -->
<script id="vertex-shader-3d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec2 a_texcoord;
uniform mat4 u_matrix;
varying vec2 v_texcoord;
void main() {
// Multiply the position by the matrix.
gl_Position = u_matrix * a_position;
// Pass the texcoord to the fragment shader.
v_texcoord = a_texcoord;
}
</script>
<!-- fragment shader -->
<script id="fragment-shader-3d" type="x-shader/x-fragment">
precision mediump float;
// Passed in from the vertex shader.
varying vec2 v_texcoord;
// The texture.
uniform sampler2D u_texture;
void main() {
gl_FragColor = texture2D(u_texture, v_texcoord);
}
</script>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="resources/webgl-utils.js"></script>
<script src="resources/m4.js"></script>
<script>
"use strict";
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
var canvas = document.querySelector("#canvas");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
// setup GLSL program
var program = webglUtils.createProgramFromScripts(gl, ["vertex-shader-3d", "fragment-shader-3d"]);
// look up where the vertex data needs to go.
var positionLocation = gl.getAttribLocation(program, "a_position");
var texcoordLocation = gl.getAttribLocation(program, "a_texcoord");
// lookup uniforms
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
var textureLocation = gl.getUniformLocation(program, "u_texture");
// Create a buffer for positions
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Put the positions in the buffer
setGeometry(gl);
// provide texture coordinates for the rectangle.
var texcoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Set Texcoords.
setTexcoords(gl);
// Create a texture.
var texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
// fill texture with 3x2 pixels
const level = 0;
const internalFormat = gl.LUMINANCE;
const width = 3;
const height = 2;
const border = 0;
const format = gl.LUMINANCE;
const type = gl.UNSIGNED_BYTE;
const data = new Uint8Array([
128, 64, 128,
0, 192, 0,
]);
const alignment = 1;
gl.pixelStorei(gl.UNPACK_ALIGNMENT, alignment);
gl.texImage2D(gl.TEXTURE_2D, level, internalFormat, width, height, border,
format, type, data);
// set the filtering so we don't need mips and it's not filtered
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
function degToRad(d) {
return d * Math.PI / 180;
}
var fieldOfViewRadians = degToRad(60);
var modelXRotationRadians = degToRad(0);
var modelYRotationRadians = degToRad(0);
// Get the starting time.
var then = 0;
requestAnimationFrame(drawScene);
// Draw the scene.
function drawScene(time) {
// convert to seconds
time *= 0.001;
// Subtract the previous time from the current time
var deltaTime = time - then;
// Remember the current time for the next frame.
then = time;
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.enable(gl.CULL_FACE);
gl.enable(gl.DEPTH_TEST);
// Animate the rotation
modelYRotationRadians += -0.7 * deltaTime;
modelXRotationRadians += -0.4 * deltaTime;
// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Turn on the position attribute
gl.enableVertexAttribArray(positionLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the position attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 3; // 3 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionLocation, size, type, normalize, stride, offset);
// Turn on the texcoord attribute
gl.enableVertexAttribArray(texcoordLocation);
// bind the texcoord buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Tell the texcoord attribute how to get data out of texcoordBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
texcoordLocation, size, type, normalize, stride, offset);
// Compute the projection matrix
var aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
var projectionMatrix =
m4.perspective(fieldOfViewRadians, aspect, 1, 2000);
var cameraPosition = [0, 0, 2];
var up = [0, 1, 0];
var target = [0, 0, 0];
// Compute the camera's matrix using look at.
var cameraMatrix = m4.lookAt(cameraPosition, target, up);
// Make a view matrix from the camera matrix.
var viewMatrix = m4.inverse(cameraMatrix);
var viewProjectionMatrix = m4.multiply(projectionMatrix, viewMatrix);
var matrix = m4.xRotate(viewProjectionMatrix, modelXRotationRadians);
matrix = m4.yRotate(matrix, modelYRotationRadians);
// Set the matrix.
gl.uniformMatrix4fv(matrixLocation, false, matrix);
// Tell the shader to use texture unit 0 for u_texture
gl.uniform1i(textureLocation, 0);
// Draw the geometry.
gl.drawArrays(gl.TRIANGLES, 0, 6 * 6);
requestAnimationFrame(drawScene);
}
}
// Fill the buffer with the values that define a cube.
function setGeometry(gl) {
var positions = new Float32Array(
[
-0.5, -0.5, -0.5,
-0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
-0.5, 0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
-0.5, -0.5, 0.5,
0.5, -0.5, 0.5,
-0.5, 0.5, 0.5,
-0.5, 0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, 0.5,
-0.5, 0.5, -0.5,
-0.5, 0.5, 0.5,
0.5, 0.5, -0.5,
-0.5, 0.5, 0.5,
0.5, 0.5, 0.5,
0.5, 0.5, -0.5,
-0.5, -0.5, -0.5,
0.5, -0.5, -0.5,
-0.5, -0.5, 0.5,
-0.5, -0.5, 0.5,
0.5, -0.5, -0.5,
0.5, -0.5, 0.5,
-0.5, -0.5, -0.5,
-0.5, -0.5, 0.5,
-0.5, 0.5, -0.5,
-0.5, -0.5, 0.5,
-0.5, 0.5, 0.5,
-0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, -0.5,
0.5, 0.5, 0.5,
]);
gl.bufferData(gl.ARRAY_BUFFER, positions, gl.STATIC_DRAW);
}
// Fill the buffer with texture coordinates the cube.
function setTexcoords(gl) {
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(
[
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
]),
gl.STATIC_DRAW);
}
main();
</script>
</html>