"use strict";
var m4 = twgl.m4;
var gl = document.getElementById("c").getContext("webgl");
// compiles shader, links and looks up locations
var programInfo = twgl.createProgramInfo(gl, ["vs", "fs"]);
var arrays = {
position: [1, 1, -1, 1, 1, 1, 1, -1, 1, 1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, 1, 1, 1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1],
texcoord: [
// select the bottom left image
0 , 0 ,
0 , 0.5,
0.25, 0.5,
0.25, 0 ,
// select the bottom middle image
0.25, 0 ,
0.5 , 0 ,
0.5 , 0.5,
0.25, 0.5,
// select to bottom right image
0.5 , 0 ,
0.5 , 0.5,
0.75, 0.5,
0.75, 0 ,
// select the top left image
0 , 0.5,
0.25, 0.5,
0.25, 1 ,
0 , 1 ,
// select the top middle image
0.25, 0.5,
0.25, 1 ,
0.5 , 1 ,
0.5 , 0.5,
// select the top right image
0.5 , 0.5,
0.75, 0.5,
0.75, 1 ,
0.5 , 1 ,
],
indices: [0, 1, 2, 0, 2, 3, 4, 5, 6, 4, 6, 7, 8, 9, 10, 8, 10, 11, 12, 13, 14, 12, 14, 15, 16, 17, 18, 16, 18, 19, 20, 21, 22, 20, 22, 23],
};
// calls gl.createBuffer, gl.bindBuffer, gl.bufferData for each array
var bufferInfo = twgl.createBufferInfoFromArrays(gl, arrays);
var ctx = document.createElement("canvas").getContext("2d");
ctx.canvas.width = 512;
ctx.canvas.height = 256;
ctx.fillRect(0, 0, 512, 256); // black to start
var tex = gl.createTexture();
uploadCanvasToTexture();
[
"https://i.imgur.com/weklTat.gif",
"https://i.imgur.com/6AvnLa3.jpg",
"https://i.imgur.com/HkzeCU2.jpg",
"https://i.imgur.com/D9HVm6n.png",
"https://i.imgur.com/7MlmkJr.jpg",
"https://i.imgur.com/v38pV.jpg",
].forEach(function(url, ndx) {
var img = new Image();
img.onload = function() {
addFaceToCanvasAndUploadToTexture(img, ndx);
};
img.crossOrigin = "";
img.src = url;
});
function addFaceToCanvasAndUploadToTexture(img, ndx) {
var x = ndx % 3;
var y = ndx / 3 | 0;
ctx.drawImage(img, 0, 0, img.width, img.height, x * 128, y * 128, 128, 128);
uploadCanvasToTexture();
}
function uploadCanvasToTexture() {
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, ctx.canvas);
gl.generateMipmap(gl.TEXTURE_2D);
}
var uniforms = {
u_texture: tex,
};
function render(time) {
time *= 0.001;
twgl.resizeCanvasToDisplaySize(gl.canvas);
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.enable(gl.DEPTH_TEST);
gl.enable(gl.CULL_FACE);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
var projection = m4.perspective(30 * Math.PI / 180, gl.canvas.clientWidth / gl.canvas.clientHeight, 0.5, 10);
var eye = [1, 4, -6];
var target = [0, 0, 0];
var up = [0, 1, 0];
var camera = m4.lookAt(eye, target, up);
var view = m4.inverse(camera);
var viewProjection = m4.multiply(view, projection);
var world = m4.rotationY(time);
uniforms.u_worldViewProjection = m4.multiply(world, viewProjection);
gl.useProgram(programInfo.program);
// calls gl.bindBuffer, gl.enableVertexAttribArray, gl.vertexAttribPointer
twgl.setBuffersAndAttributes(gl, programInfo, bufferInfo);
// calls gl.uniformXXX, gl.activeTexture, gl.bindTexture
twgl.setUniforms(programInfo, uniforms);
// calls gl.drawArray or gl.drawElements
twgl.drawBufferInfo(gl, gl.TRIANGLES, bufferInfo);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
body { margin: 0px; }
canvas { width: 100vw; height: 100vh; display: block; }
<script id="vs" type="notjs">
uniform mat4 u_worldViewProjection;
attribute vec4 position;
attribute vec2 texcoord;
varying vec2 v_texCoord;
void main() {
v_texCoord = texcoord;
gl_Position = u_worldViewProjection * position;
}
</script>
<script id="fs" type="notjs">
precision mediump float;
varying vec2 v_texCoord;
uniform sampler2D u_texture;
void main() {
gl_FragColor = texture2D(u_texture, v_texCoord);
}
</script>
<script src="https://twgljs.org/dist/twgl-full.min.js"></script>
<canvas id="c"></canvas>