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(function () {
var preTag = document.getElementById('donut');
// Angles, Radius and Contants
var A = 1;
var B = 1;
var R1 = 1;
var R2 = 2;
var K1 = 150;
var K2 = 5;
// Function to render ASCII frame
function renderAsciiFrame() {
var b = []; // Array to stay acii chars
var z = []; // Array to store depth values
var width = 280; // Width of frame
var height = 160; // Height of frame
A += 0.07; // Increament angle a
B += 0.03; // Increament angle b
// Sin and Cosine of angles
var cA = Math.cos(A),
sA = Math.sin(A),
cB = Math.cos(B),
sB = Math.sin(B);
// Initialize arrays with default angles
for (var k = 0; k < width * height; k++) {
// Set default ascii char
b[k] = k % width == width - 1 ? '\n' : ' ';
// Set default depth
z[k] = 0;
}
// Generate the ascii frame
for (var j = 0; j < 6.28; j += 0.07) {
var ct = Math.cos(j); // Cosine of j
var st = Math.sin(j); // Sin of j
for (var i = 0; i < 6.28; i += 0.02) {
var sp = Math.sin(i); // Sin of i
cp = Math.cos(i), // Cosine of i
h = ct + 2, // Height calculation
// Distance calculation
D = 1 / (sp * h * sA + st * cA + 5),
// Temporary variable
t = sp * h * cA - st * sA;
// Calculate cordinates of ascii char
var x = Math.floor(width / 2 + (width / 4) * D * (cp * h * cB - t * sB));
var y = Math.floor(height / 2 + (height / 4) * D * (cp * h * sB + t * cB));
// Calculate the index in the array
var o = x + width * y;
// Calculate the ascii char index
var N = Math.floor(8 * ((st * sA - sp * ct * cA) * cB - sp * ct * sA - st * cA - cp * ct * sB));
// Update ascii char and depth if conditions are met
if (y < height && y >= 0 && x >= 0 && x < width && D > z[o]) {
z[o] = D;
// Update ascii char based on the index
b[o] = '.,-~:;=!*#$@'[N > 0 ? N : 0];
}
}
}
// Update html element with the ascii frame
preTag.innerHTML = b.join('');
}
// Function to start the animation
function startAsciiAnimation() {
// Start it by calling renderAsciiAnimation every 50ms
window.asciiIntervalId = setInterval(renderAsciiFrame, 50);
}
renderAsciiFrame(); // Render the initial ascii frame
// Add event listener to start animation when page is loaded
if (document.all) {
// For older versions of internet explorer
window.attachEvent('onload', startAsciiAnimation);
} else {
// For modern browsers
window.addEventListener('load', startAsciiAnimation, false);
}
// Add event listener to update ascii frame when window resized
window.addEventListener('resize', renderAsciiFrame);
})();