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Main code implementation:
HTML code:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>彩带特效</title>
</head>
<body>
<script id="fs" type="x-shader/x-fragment">
precision mediump float; uniform float time; uniform vec2 mouse; uniform vec2 resolution; // window ratio float ratio = resolution.x / resolution.y; float PI = 3.1415926; float line(vec2 p, float pct, float i) { return smoothstep(pct - sin(time / i) *
0.06, pct, p.y) - smoothstep(pct, pct + sin(time / i) * 0.06, p.y); } vec2 rotate2d(vec2 p, float angle) { p = mat2(cos(angle), -sin(angle), sin(angle), cos(angle)) * p; return p; } void main(void) { // center center vec2 p = vec2(gl_FragCoord.xy
* 2.0 - resolution) / min(resolution.x, resolution.y); // left bottom //vec2 p = gl_FragCoord.xy / resolution.xy; float l = length(p); vec3 c = vec3(0.0); vec3 d = vec3(l, 1.0 - p.x, 1.0 - p.y); for (float i = 1.0; i
<=3 6.0; i++) { p=r
otate2d(p, i * 10.0); float s=t ime / i; float y=s in(p.x + s) * 0.4 * l; float pct=l ine(p, y, i); c +=p ct; } gl_FragColor=v ec4(c * d, 1.0); } </script>
<script id="vs" type="x-shader/x-vertex">
attribute vec3 position; void main(void){ gl_Position = vec4(position, 1.0); }
</script>
<script>
// variable for global
let c, // canvas
cw, ch, // window size
mx, my, // mouse
gl, // context
uniLocation, // for shader
run, // not used
eCheck, // not used
startTime, time, tempTime; // times
/**
* Make canvas
*/
const createCanvas = () => {
const b = document.getElementsByTagName('body')[0];
const c = document.createElement('canvas');
c.setAttribute('id', 'canvas');
c.style.position = 'fixed';
c.style.display = 'block';
c.style.zIndex = '-1';
c.style.top = '0';
c.style.left = '0';
c.style.width = '100%';
c.style.height = '100%';
c.style.background = 'black';
b.appendChild(c);
};
/**
* Check event
* @params {Object} e - check event
*/
const checkChange = e => {
run = e.currentTarget.checked;
if (run) {
startTime = new Date().getTime();
render();
} else {
tempTime += time;
}
};
/**
* Mouse event
* @params {Object} e - mouse event
*/
const mouseMove = e => {
mx = e.clientX / cw;
my = e.clientY / ch;
};
/**
* Resize window
*/
const resizeWindow = () => {
cw = c.width = window.innerWidth;
ch = c.height = window.innerHeight;
init();
};
/**
* Rendering function
*/
const render = () => {
// run?
if (!run) return;
// time
time = (new Date().getTime() - startTime) * 0.001;
// clear color
gl.clear(gl.COLOR_BUFFER_BIT);
// uniforms
gl.uniform1f(uniLocation[0], time);
gl.uniform2fv(uniLocation[1], [mx, my]);
gl.uniform2fv(uniLocation[2], [cw, ch]);
// draw
gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
gl.flush();
// recur
requestAnimationFrame(render);
};
/**
* Create shader
* @params {String} id - element id
* @return {Object} shader - shader object
*/
const create_shader = id => {
let shader;
// get reference tag
const scriptElement = document.getElementById(id);
// if not exsist return
if (!scriptElement) return;
// check script attribute
switch (scriptElement.type) {
// vertex shader
case 'x-shader/x-vertex':
shader = gl.createShader(gl.VERTEX_SHADER);
break;
// fragment shader
case 'x-shader/x-fragment':
shader = gl.createShader(gl.FRAGMENT_SHADER);
break;
default:
return;
}
// assign source to shader
gl.shaderSource(shader, scriptElement.text);
// compile shader
gl.compileShader(shader);
// check shader was compiled?
if (gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
return shader;
} else {
console.log(gl.getShaderInfoLog(shader));
}
};
/**
* Create program object and link shader function
* @param {String} vs - element name
* @param {String} fs - element name
* @return {object} program - return program object
*/
const create_program = (vs, fs) => {
let program;
// create program object
program = gl.createProgram();
// attach shader program object
gl.attachShader(program, vs);
gl.attachShader(program, fs);
// link shader
gl.linkProgram(program);
// check shader link
if (gl.getProgramParameter(program, gl.LINK_STATUS)) {
// if success enable program
gl.useProgram(program);
return program;
} else {
return null;
}
};
/**
* Create vbo function
* @param {Array} - Array in position
* @return {Object} - vertex buffer object
*/
const create_vbo = data => {
//create buffer object
const vbo = gl.createBuffer();
// bind buffer
gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
// set data to buffer
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
// invalidata buffer
gl.bindBuffer(gl.ARRAY_BUFFER, null);
return vbo;
};
/**
* Create index buffer object function
* @param {Array} data - Array in index
* @return {Object} ibo - index buffer object
*/
const create_ibo = data => {
// create buffer object
const ibo = gl.createBuffer();
// bind buffer
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ibo);
// set data to buffer
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Int16Array(data), gl.STATIC_DRAW);
// invalidate buffer
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, null);
return ibo;
};
/**
* Init canvas
*/
const init = () => {
time = 0.0;
tempTime = 0.0;
uniLocation = new Array();
// get element
c = document.getElementById('canvas');
//eCheck = document.getElementById('check');
// canvas size
cw = c.width = window.innerWidth;
ch = c.height = window.innerHeight;
// get webgl context
gl = c.getContext('webgl') || c.getContext('experimental-webgl');
// set viewport
gl.viewport(0, 0, cw, ch);
// init shader
const prg = create_program(create_shader('vs'), create_shader('fs'));
run = prg != null;
if (!run) {
eCheck.checked = false;
}
uniLocation[0] = gl.getUniformLocation(prg, 'time');
uniLocation[1] = gl.getUniformLocation(prg, 'mouse');
uniLocation[2] = gl.getUniformLocation(prg, 'resolution');
// init vertex
const position = [-1.0, 1.0, 0.0,
1.0, 1.0, 0.0, -1.0, -1.0, 0.0,
1.0, -1.0, 0.0
];
const index = [
0, 2, 1,
1, 2, 3
];
const vPosition = create_vbo(position);
const vIndex = create_ibo(index);
const vAttLocation = gl.getAttribLocation(prg, 'position');
gl.bindBuffer(gl.ARRAY_BUFFER, vPosition);
gl.enableVertexAttribArray(vAttLocation);
gl.vertexAttribPointer(vAttLocation, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, vIndex);
// etc init
gl.clearColor(0.0, 0.0, 0.0, 1.0);
mx = 0.5;
my = 0.5;
startTime = new Date().getTime();
};
window.addEventListener('load', () => {
createCanvas();
init();
render();
// event
c.addEventListener('mousemove', mouseMove, false);
//eCheck.addEventListener('change', checkChange, false);
window.addEventListener('resize', resizeWindow, false);
}, false);
</script>
</body>
</html>
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