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<!-- vim: sw=4 ts=4 expandtab smartindent ft=javascript
-->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>WebGL Demo</title>
<style> document, body { margin: 0px; padding: 0px; overflow: hidden; } </style>
</head>
<body>
<canvas id="glcanvas"></canvas>
<script>
const canvas = document.getElementById('glcanvas');
const gl = canvas.getContext('webgl', {antialias: true});
if (!gl) { alert('Failed to initialize WebGL'); }
(window.onresize = () => {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
/* account for e.g. high-retina macbook screens */
if (window.devicePixelRatio > 1) {
canvas.style.width = `${canvas.width}px`;
canvas.style.height = `${canvas.height}px`;
canvas.width *= window.devicePixelRatio;
canvas.height *= window.devicePixelRatio;
}
gl.viewport(
0,
0,
canvas.width,
canvas.height
);
})();
let shaders;
/* compile shaders */
{
const vs_geo = `
attribute vec3 a_pos;
attribute vec4 a_color;
uniform mat4 u_matrix;
varying vec4 v_color;
void main() {
gl_Position = u_matrix * vec4(a_pos.xyz, 1);
v_color = a_color;
}`;
const fs_geo = `
precision mediump float;
varying vec4 v_color;
void main() {
gl_FragColor = vec4(v_color.xyz*0.3, 1.0);
}`;
function createProgram(gl, vertexSource, fragmentSource) {
function createShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
throw new Error(gl.getShaderInfoLog(shader));
}
return shader;
}
const program = gl.createProgram();
const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexSource);
const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentSource);
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
throw new Error(gl.getProgramInfoLog(program));
}
const wrapper = {program};
const numAttributes = gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES);
for (let i = 0; i < numAttributes; i++) {
const attribute = gl.getActiveAttrib(program, i);
wrapper[attribute.name] = gl.getAttribLocation(program, attribute.name);
}
const numUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
for (let i = 0; i < numUniforms; i++) {
const uniform = gl.getActiveUniform(program, i);
wrapper[uniform.name] = gl.getUniformLocation(program, uniform.name);
}
return wrapper;
}
shaders = {
geo: createProgram(gl, vs_geo, fs_geo)
}
}
const geo_vbuf_pos = gl.createBuffer();
const geo_vbuf_color = gl.createBuffer();
const geo_ibuf = gl.createBuffer();
requestAnimationFrame(function frame(timestamp) {
requestAnimationFrame(frame);
const geo_idx = [];
const geo_pos = [];
const geo_color = [];
const ORTHO = false;
const mvp = mat4_create();
{
const model = mat4_create();
{
const scratch = mat4_create();
mat4_from_z_rotation(model, Date.now() * 0.0002);
// mat4_from_x_rotation(scratch, Date.now() * 0.0002);
// mat4_mul(model, scratch, model);
mat4_from_scaling(scratch, 0.5)
mat4_mul(model, scratch, model);
}
if (ORTHO) {
const ar = window.innerWidth / window.innerHeight;
const projection = mat4_ortho(mat4_create(), -ar, ar, -1, 1, -2, 2);
mat4_mul(mvp, projection, model);
} else {
const FIELD_OF_VIEW = 75 / 180 * Math.PI;
const ar = window.innerWidth / window.innerHeight;
const projection = mat4_perspective(mat4_create(), FIELD_OF_VIEW, ar, 0.01, 100.0);
const view = mat4_target_to(mat4_create(), [5, 5, 5], [0, 0, 0], [0, 0, 1]);
mat4_invert(view, view);
mat4_mul(mvp, projection, view);
mat4_mul(mvp, mvp, model);
}
}
{
const corners = [
-1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, /* Top face */
-1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, /* Bottom face */
-1, 1, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, /* Front face */
-1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, /* Back face */
1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, /* Right face */
-1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, /* Left face */
];
for (let corner_i = 0; corner_i < corners.length; corner_i += 3)
corners[corner_i+2] += 1;
for (let corner_i = 0; corner_i < corners.length; corner_i += 12) {
geo_color.push(
255, 0, 0, 255,
0, 255, 0, 255,
0, 0, 255, 255,
255, 0, 255, 255
)
const vbuf_i = geo_pos.length / 3;
geo_pos.push(corners[corner_i + 0], corners[corner_i + 1], corners[corner_i + 2]);
geo_pos.push(corners[corner_i + 3], corners[corner_i + 4], corners[corner_i + 5]);
geo_pos.push(corners[corner_i + 6], corners[corner_i + 7], corners[corner_i + 8]);
geo_pos.push(corners[corner_i + 9], corners[corner_i + 10], corners[corner_i + 11]);
geo_idx.push(
vbuf_i + 0,
vbuf_i + 1,
vbuf_i + 2,
vbuf_i + 2,
vbuf_i + 3,
vbuf_i + 0
);
}
}
{
/* set up premultiplied alpha */
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
/* clear all */
gl.clearColor(0, 0, 0, 1);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
/* geo pass */
{
gl.useProgram(shaders.geo.program);
gl.enableVertexAttribArray(shaders.geo.a_pos);
gl.enableVertexAttribArray(shaders.geo.a_color);
gl.uniformMatrix4fv(shaders.geo.u_matrix, false, mvp);
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo_pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_color);
gl.bufferData(gl.ARRAY_BUFFER, new Uint8Array(geo_color), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_color, 4, gl.UNSIGNED_BYTE, true, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, geo_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(geo_idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, geo_idx.length, gl.UNSIGNED_SHORT, 0);
}
}
})
function mat4_create() {
let out = new Float32Array(16);
out[0] = 1;
out[5] = 1;
out[10] = 1;
out[15] = 1;
return out;
}
function mat4_ortho(out, left, right, bottom, top, near, far) {
let lr = 1 / (left - right);
let bt = 1 / (bottom - top);
let nf = 1 / (near - far);
out[0] = -2 * lr;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = -2 * bt;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[10] = 2 * nf;
out[11] = 0;
out[12] = (left + right) * lr;
out[13] = (top + bottom) * bt;
out[14] = (far + near) * nf;
out[15] = 1;
return out;
}
function mat4_invert(out, a) {
let a00 = a[0], a01 = a[1], a02 = a[2], a03 = a[3];
let a10 = a[4], a11 = a[5], a12 = a[6], a13 = a[7];
let a20 = a[8], a21 = a[9], a22 = a[10], a23 = a[11];
let a30 = a[12], a31 = a[13], a32 = a[14], a33 = a[15];
let b00 = a00 * a11 - a01 * a10;
let b01 = a00 * a12 - a02 * a10;
let b02 = a00 * a13 - a03 * a10;
let b03 = a01 * a12 - a02 * a11;
let b04 = a01 * a13 - a03 * a11;
let b05 = a02 * a13 - a03 * a12;
let b06 = a20 * a31 - a21 * a30;
let b07 = a20 * a32 - a22 * a30;
let b08 = a20 * a33 - a23 * a30;
let b09 = a21 * a32 - a22 * a31;
let b10 = a21 * a33 - a23 * a31;
let b11 = a22 * a33 - a23 * a32;
/* Calculate the determinant */
let det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;
if (!det) {
return null;
}
det = 1.0 / det;
out[0] = (a11 * b11 - a12 * b10 + a13 * b09) * det;
out[1] = (a02 * b10 - a01 * b11 - a03 * b09) * det;
out[2] = (a31 * b05 - a32 * b04 + a33 * b03) * det;
out[3] = (a22 * b04 - a21 * b05 - a23 * b03) * det;
out[4] = (a12 * b08 - a10 * b11 - a13 * b07) * det;
out[5] = (a00 * b11 - a02 * b08 + a03 * b07) * det;
out[6] = (a32 * b02 - a30 * b05 - a33 * b01) * det;
out[7] = (a20 * b05 - a22 * b02 + a23 * b01) * det;
out[8] = (a10 * b10 - a11 * b08 + a13 * b06) * det;
out[9] = (a01 * b08 - a00 * b10 - a03 * b06) * det;
out[10] = (a30 * b04 - a31 * b02 + a33 * b00) * det;
out[11] = (a21 * b02 - a20 * b04 - a23 * b00) * det;
out[12] = (a11 * b07 - a10 * b09 - a12 * b06) * det;
out[13] = (a00 * b09 - a01 * b07 + a02 * b06) * det;
out[14] = (a31 * b01 - a30 * b03 - a32 * b00) * det;
out[15] = (a20 * b03 - a21 * b01 + a22 * b00) * det;
return out;
}
function mat4_perspective(out, fovy, aspect, near, far) {
let f = 1.0 / Math.tan(fovy / 2),
nf;
out[0] = f / aspect;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = f;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[11] = -1;
out[12] = 0;
out[13] = 0;
out[15] = 0;
if (far != null && far !== Infinity) {
nf = 1 / (near - far);
out[10] = (far + near) * nf;
out[14] = 2 * far * near * nf;
} else {
out[10] = -1;
out[14] = -2 * near;
}
return out;
}
function mat4_from_x_rotation(out, rad) {
let s = Math.sin(rad);
let c = Math.cos(rad);
/* Perform axis-specific matrix multiplication */
out[0] = 1;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = c;
out[6] = s;
out[7] = 0;
out[8] = 0;
out[9] = -s;
out[10] = c;
out[11] = 0;
out[12] = 0;
out[13] = 0;
out[14] = 0;
out[15] = 1;
return out;
}
function mat4_from_y_rotation(out, rad) {
let s = Math.sin(rad);
let c = Math.cos(rad);
/* Perform axis-specific matrix multiplication */
out[0] = c;
out[1] = 0;
out[2] = -s;
out[3] = 0;
out[4] = 0;
out[5] = 1;
out[6] = 0;
out[7] = 0;
out[8] = s;
out[9] = 0;
out[10] = c;
out[11] = 0;
out[12] = 0;
out[13] = 0;
out[14] = 0;
out[15] = 1;
return out;
}
function mat4_from_z_rotation(out, rad) {
let s = Math.sin(rad);
let c = Math.cos(rad);
/* Perform axis-specific matrix multiplication */
out[0] = c;
out[1] = s;
out[2] = 0;
out[3] = 0;
out[4] = -s;
out[5] = c;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[10] = 1;
out[11] = 0;
out[12] = 0;
out[13] = 0;
out[14] = 0;
out[15] = 1;
return out;
}
function mat4_from_scaling(out, f) {
out[0] = f;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = f;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[10] = f;
out[11] = 0;
out[12] = 0;
out[13] = 0;
out[14] = 0;
out[15] = 1;
return out;
}
function mat4_from_translation(out, v) {
out[0] = 1;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = 1;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[10] = 1;
out[11] = 0;
out[12] = v[0];
out[13] = v[1];
out[14] = v[2];
out[15] = 1;
return out;
}
function mat4_transform_vec4(out, a, m) {
let x = a[0], y = a[1], z = a[2], w = a[3];
out[0] = m[0] * x + m[4] * y + m[8] * z + m[12] * w;
out[1] = m[1] * x + m[5] * y + m[9] * z + m[13] * w;
out[2] = m[2] * x + m[6] * y + m[10] * z + m[14] * w;
out[3] = m[3] * x + m[7] * y + m[11] * z + m[15] * w;
return out;
}
function mat4_mul(out, a, b) {
let a00 = a[0], a01 = a[1], a02 = a[2], a03 = a[3];
let a10 = a[4], a11 = a[5], a12 = a[6], a13 = a[7];
let a20 = a[8], a21 = a[9], a22 = a[10], a23 = a[11];
let a30 = a[12], a31 = a[13], a32 = a[14], a33 = a[15];
/* Cache only the current line of the second matrix */
let b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3];
out[0] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
out[1] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
out[2] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
out[3] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;
b0 = b[4];
b1 = b[5];
b2 = b[6];
b3 = b[7];
out[4] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
out[5] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
out[6] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
out[7] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;
b0 = b[8];
b1 = b[9];
b2 = b[10];
b3 = b[11];
out[8] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
out[9] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
out[10] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
out[11] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;
b0 = b[12];
b1 = b[13];
b2 = b[14];
b3 = b[15];
out[12] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
out[13] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
out[14] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
out[15] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;
return out;
}
function mat4_target_to(out, eye, target, up=VEC3_UP) {
let eyex = eye[0], eyey = eye[1], eyez = eye[2],
upx = up[0], upy = up[1], upz = up[2];
let z0 = eyex - target[0],
z1 = eyey - target[1],
z2 = eyez - target[2];
let len = z0 * z0 + z1 * z1 + z2 * z2;
if (len > 0) {
len = 1 / Math.sqrt(len);
z0 *= len;
z1 *= len;
z2 *= len;
}
let x0 = upy * z2 - upz * z1,
x1 = upz * z0 - upx * z2,
x2 = upx * z1 - upy * z0;
len = x0 * x0 + x1 * x1 + x2 * x2;
if (len > 0) {
len = 1 / Math.sqrt(len);
x0 *= len;
x1 *= len;
x2 *= len;
}
out[0] = x0;
out[1] = x1;
out[2] = x2;
out[3] = 0;
out[4] = z1 * x2 - z2 * x1;
out[5] = z2 * x0 - z0 * x2;
out[6] = z0 * x1 - z1 * x0;
out[7] = 0;
out[8] = z0;
out[9] = z1;
out[10] = z2;
out[11] = 0;
out[12] = eyex;
out[13] = eyey;
out[14] = eyez;
out[15] = 1;
return out;
}
</script>
</body>
</html>