Icosahedron - rendered in 2D
Old School 3D convex hull rendering using cross product in screenspace for backface culling removal and subsequent shading. What is a icosahedron - rendered in 2d How do you make a icosahedron - rendered in 2d? This script and codes were developed by Andi Smithers on 25 January 2022, Tuesday.
How do I make an icosahedron - rendered in 2d?Icosahedron - rendered in 2D Previews
Icosahedron - rendered in 2D HTML Codes
<!DOCTYPE html>
<html >
<head>
<meta charset="UTF-8">
<title>Icosahedron - rendered in 2D</title>
<link rel="stylesheet" href="css/style.css">
</head>
<body>
<body>
<canvas id='icosahedron 3d'></canvas>
</body>
<script src="js/index.js"></script>
</body>
</html>
Icosahedron - rendered in 2D CSS Codes
body{
background:#000000;
margin: 0px;
padding: 0px;
}
Icosahedron - rendered in 2D JS Codes
/*****************************************************************************
The MIT License (MIT)
Copyright (c) 2014 Andi Smithers
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*****************************************************************************/
// conceptualized and written by andi smithers
// constant options
const focalDepth = 80;
const focalPoint = 256;
// variables
var centreX;
var centreY;
var mouseX;
var mouseY;
var spawnX;
var spawnY;
var frameCount=0;
var shieldUp;
var splutterCount=0;
var splutterNoise=60;
// test multiple groups
var icosahedronVerts = [];
var icosahedronTris = [];
function buildVerts()
{
icosahedronVerts =
[
{x: 0.000, y: 0.000, z: 1.000},
{x: 0.894, y: 0.000, z: 0.447},
{x: 0.276, y: 0.851, z: 0.447},
{x:-0.724, y: 0.526, z: 0.447},
{x:-0.724, y:-0.526, z: 0.447},
{x: 0.276, y:-0.851, z: 0.447},
{x: 0.724, y: 0.526, z:-0.447},
{x:-0.276, y: 0.851, z:-0.447},
{x:-0.894, y: 0.000, z:-0.447},
{x:-0.276, y:-0.851, z:-0.447},
{x: 0.724, y:-0.526, z:-0.447},
{x: 0.000, y: 0.000, z:-1.000}
];
icosahedronTris =
[
0,1,2,
0,2,3,
0,3,4,
0,4,5,
0,5,1,
11,7,6,
11,8,7,
11,9,8,
11,10,9,
11,6,10,
2,1,6,
2,7,3,
3,8,4,
4,9,5,
5,10,1,
6,7,2,
7,8,3,
8,9,4,
9,10,5,
10,6,1
];
}
// initialization
function init()
{
// setup canvas and context
canvas = document.getElementById('icosahedron 3d');
context = canvas.getContext('2d');
// set canvas to be window dimensions
resize();
// create event listeners
canvas.addEventListener('mousemove', mouseMove);
canvas.addEventListener('click', mouseClick);
window.addEventListener('resize', resize);
// initialze variables
buildVerts();
}
// input functions
function mouseMove(event)
{
var rect = canvas.getBoundingClientRect();
mouseX = event.clientX - rect.left,
mouseY = event.clientY - rect.top
}
function mouseClick()
{
shieldUp^=1;
splutterCount = 30;
splutterNoise = 60;
}
function resize()
{
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
// compute centre of screen
centreX = canvas.width/2;
centreY = canvas.height/2;
}
// rendering functions
var phi = Math.PI*0.5;
var theta = 0;
function renderIcosahedron()
{
var scale = 512/canvas.height;
phi+=0.009;
theta+=0.01;
var transforms = [];
var cphi = Math.cos(phi);
var sphi = Math.sin(phi);
var ctheta = Math.cos(theta);
var stheta = Math.sin(theta);
// transform into 3d coords
for (var i=0; i<icosahedronVerts.length; i++)
{
var vert = icosahedronVerts[i];
var tz = vert.z * ctheta + vert.y * stheta;
var ty = vert.y * ctheta - vert.z * stheta;
// rotate phi
var tx = vert.x * cphi - ty * sphi;
ty = ty * cphi + vert.x * sphi;
// pixel depth using a long focal distance to ensure all set is in focus
var depth = focalPoint*5 / ((tz + 5*scale) +1);
var x1 = tx*depth+centreX;
var y1 = ty*depth+centreY;
transforms.push( {x:x1, y:y1, z:tz} );
}
for (var i=0; i<icosahedronTris.length;i+=3)
{
var a = icosahedronTris[i];
var b = icosahedronTris[i+1];
var c = icosahedronTris[i+2];
// back face cull
var dx1 = transforms[b].x - transforms[a].x;
var dy1 = transforms[b].y - transforms[a].y;
var dx2 = transforms[b].x - transforms[c].x;
var dy2 = transforms[b].y - transforms[c].y;
var cross = (dx1*dy2 - dy1*dx2);
if (cross < 0) continue;
// use cross product normal to reflect light
var shade = Math.floor(Math.sqrt(cross)*scale)+10;
// fill the triangle
context.beginPath();
context.moveTo(transforms[a].x, transforms[a].y);
context.lineTo(transforms[b].x, transforms[b].y);
context.lineTo(transforms[c].x, transforms[c].y);
context.closePath();
context.fillStyle = 'rgba('+shade+','+shade+','+shade+',1)';
context.fill();
// edge it in red for fun
context.lineWidth = 4;
context.strokeStyle = 'rgba('+(shade>>2)+','+(shade>>2)+','+shade+', 1)';
context.stroke();
}
}
var spin =0;
function renderShield()
{
var phi = Math.PI*0.5;
var theta = spin;
var transforms = [];
var cphi = Math.cos(phi);
var sphi = Math.sin(phi);
var ctheta = Math.cos(theta);
var stheta = Math.sin(theta);
// transform into 3d coords
for (var i=0; i<icosahedronVerts.length; i++)
{
var vert = icosahedronVerts[i];
var tz = vert.z * ctheta + vert.y * stheta;
var ty = vert.y * ctheta - vert.z * stheta;
// rotate phi
var tx = vert.x * cphi - ty * sphi;
ty = ty * cphi + vert.x * sphi;
// pixel depth using a long focal distance to ensure all set is in focus
var depth = 1200 / ((tz + 0.2*256/canvas.height) +1);
var x1 = tx*depth+centreX;
var y1 = ty*depth+centreY;
transforms.push( {x:x1, y:y1, z:tz} );
}
for (var i=0; i<icosahedronTris.length;i+=3)
{
var a = icosahedronTris[i];
var b = icosahedronTris[i+1];
var c = icosahedronTris[i+2];
// back face cull
var dx1 = transforms[b].x - transforms[a].x;
var dy1 = transforms[b].y - transforms[a].y;
var dx2 = transforms[b].x - transforms[c].x;
var dy2 = transforms[b].y - transforms[c].y;
var cross = (dx1*dy2 - dy1*dx2);
if (cross > 0) continue;
// use cross product normal to reflect light
var shade = Math.floor(Math.sqrt(-cross));
// fill the triangle
context.beginPath();
context.moveTo(transforms[a].x, transforms[a].y);
context.lineTo(transforms[b].x, transforms[b].y);
context.lineTo(transforms[c].x, transforms[c].y);
context.closePath();
context.fillStyle = 'rgba('+0+','+shade+','+0+',0.25)';
context.fill();
// edge it in red for fun
context.lineWidth = 1;
context.strokeStyle = 'rgba('+0+','+shade+','+0+', 0.1)';
context.stroke();
}
}
function render()
{
context.fillStyle = 'black';
context.clearRect(0, 0, canvas.width, canvas.height);
context.globalCompositeOperation='lighter';
renderIcosahedron();
splutterNoise++;
spin+=0.01;
if (splutterCount) splutterCount--;
var splutter = splutterNoise&splutterCount;
if ( shieldUp & !splutter) renderShield();
context.globalCompositeOperation='source-over';
context.globalAlpha = 1.0;
context.font = '20pt Calibri';
context.fillStyle = 'rgb(255,255,255)';
context.textAlign = "center";
context.fillText('Icosahedron', canvas.width/2, 20);
context.font = '14pt Calibri';
context.fillText('(mouse button to Shield Up)', canvas.width/2, 40);
}
// movement functions
function update()
{
}
// per frame tick functions
function animate()
{
frameCount++;
// movement update
update();
// render update
render();
// trigger next frame
requestAnimationFrame(animate);
}
// entry point
init();
animate();
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