最近在看webgl和threejs

终于发现线性代数的重要

很后悔大学时代根本没好好学数学,webgl看到矩阵变换就懵逼了,买了本大学的教材准备有时间补补再看

所以先试试three.js的demo吧

主页背景的效果用的是这个

代码稍微修改了下,集成到了hexo内

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if ( ! Detector.webgl ) Detector.addGetWebGLMessage();

var hash = document.location.hash.substr( 1 );
if (hash) hash = parseInt(hash, 0);

/* TEXTURE WIDTH FOR SIMULATION */
var WIDTH = hash || 32;

var BIRDS = WIDTH * WIDTH;

// Custom Geometry - using 3 triangles each. No UVs, no normals currently.
THREE.BirdGeometry = function () {

var triangles = BIRDS * 3;
var points = triangles * 3;

THREE.BufferGeometry.call( this );
var vertices = new THREE.BufferAttribute( new Float32Array( points * 3 ), 3 );
var birdColors = new THREE.BufferAttribute( new Float32Array( points * 3 ), 3 );
var references = new THREE.BufferAttribute( new Float32Array( points * 2 ), 2 );
var birdVertex = new THREE.BufferAttribute( new Float32Array( points ), 1 );

this.addAttribute( 'position', vertices );
this.addAttribute( 'birdColor', birdColors );
this.addAttribute( 'reference', references );
this.addAttribute( 'birdVertex', birdVertex );

// this.addAttribute( 'normal', new Float32Array( points * 3 ), 3 );


var v = 0;

function verts_push() {
for (var i=0; i < arguments.length; i++) {
vertices.array[v++] = arguments[i];
}
}

var wingsSpan = 20;

for (var f = 0; f<BIRDS; f++ ) {

// Body
verts_push(
0, -0, -20,
0, 4, -20,
0, 0, 30
);

// Left Wing
verts_push(
0, 0, -15,
-wingsSpan, 0, 0,
0, 0, 15
);

// Right Wing
verts_push(
0, 0, 15,
wingsSpan, 0, 0,
0, 0, -15
);

}

for( var v = 0; v < triangles * 3; v++ ) {

var i = ~~(v / 3);
var x = (i % WIDTH) / WIDTH;
var y = ~~(i / WIDTH) / WIDTH;

var c = new THREE.Color(
0x444444 +
~~(v / 9) / BIRDS * 0x666666
);

birdColors.array[ v * 3 + 0 ] = c.r;
birdColors.array[ v * 3 + 1 ] = c.g;
birdColors.array[ v * 3 + 2 ] = c.b;

references.array[ v * 2 ] = x;
references.array[ v * 2 + 1 ] = y;

birdVertex.array[ v ] = v % 9;

}

this.scale( 0.2, 0.2, 0.2 );

};

THREE.BirdGeometry.prototype = Object.create( THREE.BufferGeometry.prototype );


var container, stats;
var camera, scene, renderer, geometry, i, h, color;
var mouseX = 0, mouseY = 0;

var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;

var BOUNDS = 800, BOUNDS_HALF = BOUNDS / 2;

// document.getElementById('birds').innerText = BIRDS;

function change(n) {
location.hash = n;
location.reload();
return false;
}


var options = '';
for (i=1; i<7; i++) {
var j = Math.pow(2, i);
options += '<a href="#" onclick="return change(' + j + ')">' + (j * j) + '</a> ';
}
// document.getElementById('options').innerHTML = options;

var last = performance.now();

var gpuCompute;
var velocityVariable;
var positionVariable;
var positionUniforms;
var velocityUniforms;
var birdUniforms;

init();
animate();

function init() {

container = document.createElement( 'div' );
container.style.width = '100%';
container.style.height = '100%';
container.style.position = 'fixed';
container.style.top = '0';
container.style.left = '0';

document.body.appendChild( container );

camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 1, 3000 );
camera.position.z = 350;

scene = new THREE.Scene();
scene.background = new THREE.Color( 0xffffff );
scene.fog = new THREE.Fog( 0xffffff, 100, 1000 );

renderer = new THREE.WebGLRenderer();
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
container.appendChild( renderer.domElement );

initComputeRenderer();

stats = new Stats();
// container.appendChild( stats.dom );

document.addEventListener( 'mousemove', onDocumentMouseMove, false );
document.addEventListener( 'touchstart', onDocumentTouchStart, false );
document.addEventListener( 'touchmove', onDocumentTouchMove, false );

//

window.addEventListener( 'resize', onWindowResize, false );



var gui = new dat.GUI();


var effectController = {
seperation: 20.0,
alignment: 20.0,
cohesion: 20.0,
freedom: 0.75
};

var valuesChanger = function() {

velocityUniforms.seperationDistance.value = effectController.seperation;
velocityUniforms.alignmentDistance.value = effectController.alignment;
velocityUniforms.cohesionDistance.value = effectController.cohesion;
velocityUniforms.freedomFactor.value = effectController.freedom;

};

valuesChanger();


gui.add( effectController, "seperation", 0.0, 100.0, 1.0 ).onChange( valuesChanger );
gui.add( effectController, "alignment", 0.0, 100, 0.001 ).onChange( valuesChanger );
gui.add( effectController, "cohesion", 0.0, 100, 0.025 ).onChange( valuesChanger );
gui.close();

initBirds();

}

function initComputeRenderer() {

gpuCompute = new GPUComputationRenderer( WIDTH, WIDTH, renderer );

var dtPosition = gpuCompute.createTexture();
var dtVelocity = gpuCompute.createTexture();
fillPositionTexture( dtPosition );
fillVelocityTexture( dtVelocity );

velocityVariable = gpuCompute.addVariable( "textureVelocity", document.getElementById( 'fragmentShaderVelocity' ).textContent, dtVelocity );
positionVariable = gpuCompute.addVariable( "texturePosition", document.getElementById( 'fragmentShaderPosition' ).textContent, dtPosition );

gpuCompute.setVariableDependencies( velocityVariable, [ positionVariable, velocityVariable ] );
gpuCompute.setVariableDependencies( positionVariable, [ positionVariable, velocityVariable ] );

positionUniforms = positionVariable.material.uniforms;
velocityUniforms = velocityVariable.material.uniforms;

positionUniforms.time = { value: 0.0 };
positionUniforms.delta = { value: 0.0 };
velocityUniforms.time = { value: 1.0 };
velocityUniforms.delta = { value: 0.0 };
velocityUniforms.testing = { value: 1.0 };
velocityUniforms.seperationDistance = { value: 1.0 };
velocityUniforms.alignmentDistance = { value: 1.0 };
velocityUniforms.cohesionDistance = { value: 1.0 };
velocityUniforms.freedomFactor = { value: 1.0 };
velocityUniforms.predator = { value: new THREE.Vector3() };
velocityVariable.material.defines.BOUNDS = BOUNDS.toFixed( 2 );

velocityVariable.wrapS = THREE.RepeatWrapping;
velocityVariable.wrapT = THREE.RepeatWrapping;
positionVariable.wrapS = THREE.RepeatWrapping;
positionVariable.wrapT = THREE.RepeatWrapping;

var error = gpuCompute.init();
if ( error !== null ) {
console.error( error );
}

}

function initBirds() {

var geometry = new THREE.BirdGeometry();

// For Vertex and Fragment
birdUniforms = {
color: { value: new THREE.Color( 0xff2200 ) },
texturePosition: { value: null },
textureVelocity: { value: null },
time: { value: 1.0 },
delta: { value: 0.0 }
};

// ShaderMaterial
var material = new THREE.ShaderMaterial( {
uniforms: birdUniforms,
vertexShader: document.getElementById( 'birdVS' ).textContent,
fragmentShader: document.getElementById( 'birdFS' ).textContent,
side: THREE.DoubleSide

});

var birdMesh = new THREE.Mesh( geometry, material );
birdMesh.rotation.y = Math.PI / 2;
birdMesh.matrixAutoUpdate = false;
birdMesh.updateMatrix();

scene.add(birdMesh);

}

function fillPositionTexture( texture ) {

var theArray = texture.image.data;

for ( var k = 0, kl = theArray.length; k < kl; k += 4 ) {

var x = Math.random() * BOUNDS - BOUNDS_HALF;
var y = Math.random() * BOUNDS - BOUNDS_HALF;
var z = Math.random() * BOUNDS - BOUNDS_HALF;

theArray[ k + 0 ] = x;
theArray[ k + 1 ] = y;
theArray[ k + 2 ] = z;
theArray[ k + 3 ] = 1;

}

}

function fillVelocityTexture( texture ) {

var theArray = texture.image.data;

for ( var k = 0, kl = theArray.length; k < kl; k += 4 ) {

var x = Math.random() - 0.5;
var y = Math.random() - 0.5;
var z = Math.random() - 0.5;

theArray[ k + 0 ] = x * 10;
theArray[ k + 1 ] = y * 10;
theArray[ k + 2 ] = z * 10;
theArray[ k + 3 ] = 1;

}

}


function onWindowResize() {

windowHalfX = window.innerWidth / 2;
windowHalfY = window.innerHeight / 2;

camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();

renderer.setSize( window.innerWidth, window.innerHeight );

}

function onDocumentMouseMove( event ) {

mouseX = event.clientX - windowHalfX;
mouseY = event.clientY - windowHalfY;

}

function onDocumentTouchStart( event ) {

if ( event.touches.length === 1 ) {

event.preventDefault();

mouseX = event.touches[ 0 ].pageX - windowHalfX;
mouseY = event.touches[ 0 ].pageY - windowHalfY;

}

}

function onDocumentTouchMove( event ) {

if ( event.touches.length === 1 ) {

event.preventDefault();

mouseX = event.touches[ 0 ].pageX - windowHalfX;
mouseY = event.touches[ 0 ].pageY - windowHalfY;

}

}

//

function animate() {

requestAnimationFrame( animate );

render();
stats.update();

}

function render() {

var now = performance.now();
var delta = (now - last) / 1000;

if (delta > 1) delta = 1; // safety cap on large deltas
last = now;

positionUniforms.time.value = now;
positionUniforms.delta.value = delta;
velocityUniforms.time.value = now;
velocityUniforms.delta.value = delta;
birdUniforms.time.value = now;
birdUniforms.delta.value = delta;

velocityUniforms.predator.value.set( 0.5 * mouseX / windowHalfX, - 0.5 * mouseY / windowHalfY, 0 );

mouseX = 10000;
mouseY = 10000;

gpuCompute.compute();

birdUniforms.texturePosition.value = gpuCompute.getCurrentRenderTarget( positionVariable ).texture;
birdUniforms.textureVelocity.value = gpuCompute.getCurrentRenderTarget( velocityVariable ).texture;

renderer.render( scene, camera );

}