Icosahedron - rendered in 2D

Developer
Andi Smithers
Size
4,246 Kb
Views
24,276

How do I make an 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 21 November 2022, Monday.

Icosahedron - rendered in 2D Previews
IQ Test

Icosahedron - rendered in 2D - Script Codes 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 - Script Codes CSS Codes

body{ background:#000000; margin: 0px; padding: 0px;
}

Icosahedron - rendered in 2D - Script Codes 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();
Icosahedron - rendered in 2D - Script Codes
Icosahedron - rendered in 2D - Script Codes
Home Page Home
Developer Andi Smithers
Username Bolloxim
Uploaded November 21, 2022
Rating 3
Size 4,246 Kb
Views 24,276
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Andi Smithers (Bolloxim) Script Codes
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A Pen by Andi Smithers
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