mirror of https://github.com/a2stuff/vnIIc.git
add server file
This commit is contained in:
Joshua Bell
parent
395231b916
commit
16af1e5a24
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@ -8,4 +8,4 @@ video, canvas { border: 2px dotted black; }
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<br>
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<button id=save>Save</button>
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<script src="vniic.js"></script>
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<script src="server.js"></script>
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@ -0,0 +1,240 @@
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(async function() {
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const $ = document.querySelector.bind(document);
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const palette = [
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/* Black1 */ [0x00, 0x00, 0x00],
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/* Green */ [0x2f, 0xbc, 0x1a],
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/* Violet */ [0xd0, 0x43, 0xe5],
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/* White1 */ [0xff, 0xff, 0xff],
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/* Black2 */ [0x00, 0x00, 0x00],
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/* Orange */ [0xd0, 0x6a, 0x1a],
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/* Blue */ [0x2f, 0x95, 0xe5],
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/* White2 */ [0xff, 0xff, 0xff]
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];
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let hires_buffer = new Uint8Array(8192);
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$('#save').addEventListener('click', e => {
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const blob = new Blob([hires_buffer], {type: 'application/octet-stream'});
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const anchor = document.createElement('a');
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anchor.download = 'image.bin';
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anchor.href = URL.createObjectURL(blob);
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document.body.appendChild(anchor);
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anchor.click();
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anchor.remove();
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URL.revokeObjectURL(anchor.href);
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});
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try {
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const mediaStream = await navigator.getDisplayMedia({video:true});
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const vid = document.createElement('video');
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vid.srcObject = mediaStream;
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vid.play();
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const quant = $('#quant');
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const qctx = quant.getContext('2d');
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const can = document.createElement('canvas');
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can.width = quant.width;
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can.height = quant.height;
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const ctx = can.getContext('2d');
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ctx.imageSmoothingQuality = 'high';
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const indexes = new Array(can.width * can.height);
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setInterval(() => {
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ctx.drawImage(vid, 0, 0, can.width, can.height);
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const imagedata = ctx.getImageData(0, 0, can.width, can.height);
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quantize(imagedata, indexes);
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convert_to_hires(indexes, hires_buffer);
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qctx.putImageData(imagedata, 0, 0);
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}, 500);
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} catch (e) {
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console.warn(`Error: ${e.name} - ${e.message}`);
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}
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// Distance in 3-space
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function distance(r1,g1,b1,r2,g2,b2) {
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const dr = r1 - r2;
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const dg = g1 - g2;
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const db = b1 - b2;
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return Math.sqrt(dr*dr + dg*dg + db*db);
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}
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function quantize(imagedata, indexes) {
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const hash = {};
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for (let i = 0; i < palette.length; ++i) {
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const entry = palette[i];
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const rgb = (entry[0] << 16) | (entry[1] << 8) | entry[2];
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hash[rgb] = i;
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}
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// Floyd-Steinberg
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function offset(x, y) {
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return 4 * (x + y * imagedata.width);
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}
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function err(x, y, er, eg, eb) {
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if (x < 0 || x >= imagedata.width || y < 0 || y >= imagedata.height)
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return;
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const i = offset(x, y);
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const data = imagedata.data;
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data[i + 0] += er;
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data[i + 1] += eg;
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data[i + 2] += eb;
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}
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const data = imagedata.data;
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for (let y = 0; y < imagedata.height; ++y) {
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for (let x = 0; x < imagedata.width; ++x) {
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const i = offset(x, y);
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const r = data[i];
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const g = data[i+1];
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const b = data[i+2];
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// Find closest in palette.
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const rgb = (r << 16) | (g << 8) | b;
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let index = hash[rgb];
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if (index === undefined) {
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let dist;
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for (let p = 0; p < palette.length; ++p) {
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const entry = palette[p];
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const d = distance(r,g,b, entry[0], entry[1], entry[2]);
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if (dist === undefined || d < dist) {
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dist = d;
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index = p;
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}
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}
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hash[rgb] = index;
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}
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const pi = palette[index];
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// Calculate error
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const err_r = data[i] - pi[0];
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const err_g = data[i+1] - pi[1];
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const err_b = data[i+2] - pi[2];
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// Update pixel
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data[i] = pi[0];
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data[i+1] = pi[1];
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data[i+2] = pi[2];
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indexes[i / 4] = index;
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// Distribute error
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err(x + 1, y, err_r * 7/16, err_g * 7/16, err_b * 7/16);
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err(x - 1, y + 1, err_r * 3/16, err_g * 3/16, err_b * 3/16);
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err(x, y + 1, err_r * 5/16, err_g * 5/16, err_b * 5/16);
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err(x + 1, y + 1, err_r * 1/16, err_g * 1/16, err_b * 1/16);
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}
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}
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}
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// Scan line mapping table for Apple II Hi-Res screen.
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// Index into the array is the y-coordinate. The value
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// in the array is the offset (in bytes) from the
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// start of the hi-res screen buffer to the start of the
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// scan line. The scan line itself is 40 bytes wide.
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const OFFSETS = [
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0x0000,0x0400,0x0800,0x0c00,0x1000,0x1400,0x1800,0x1c00,
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0x0080,0x0480,0x0880,0x0c80,0x1080,0x1480,0x1880,0x1c80,
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0x0100,0x0500,0x0900,0x0d00,0x1100,0x1500,0x1900,0x1d00,
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0x0180,0x0580,0x0980,0x0d80,0x1180,0x1580,0x1980,0x1d80,
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0x0200,0x0600,0x0a00,0x0e00,0x1200,0x1600,0x1a00,0x1e00,
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0x0280,0x0680,0x0a80,0x0e80,0x1280,0x1680,0x1a80,0x1e80,
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0x0300,0x0700,0x0b00,0x0f00,0x1300,0x1700,0x1b00,0x1f00,
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0x0380,0x0780,0x0b80,0x0f80,0x1380,0x1780,0x1b80,0x1f80,
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0x0028,0x0428,0x0828,0x0c28,0x1028,0x1428,0x1828,0x1c28,
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0x00a8,0x04a8,0x08a8,0x0ca8,0x10a8,0x14a8,0x18a8,0x1ca8,
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0x0128,0x0528,0x0928,0x0d28,0x1128,0x1528,0x1928,0x1d28,
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0x01a8,0x05a8,0x09a8,0x0da8,0x11a8,0x15a8,0x19a8,0x1da8,
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0x0228,0x0628,0x0a28,0x0e28,0x1228,0x1628,0x1a28,0x1e28,
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0x02a8,0x06a8,0x0aa8,0x0ea8,0x12a8,0x16a8,0x1aa8,0x1ea8,
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0x0328,0x0728,0x0b28,0x0f28,0x1328,0x1728,0x1b28,0x1f28,
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0x03a8,0x07a8,0x0ba8,0x0fa8,0x13a8,0x17a8,0x1ba8,0x1fa8,
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0x0050,0x0450,0x0850,0x0c50,0x1050,0x1450,0x1850,0x1c50,
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0x00d0,0x04d0,0x08d0,0x0cd0,0x10d0,0x14d0,0x18d0,0x1cd0,
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0x0150,0x0550,0x0950,0x0d50,0x1150,0x1550,0x1950,0x1d50,
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0x01d0,0x05d0,0x09d0,0x0dd0,0x11d0,0x15d0,0x19d0,0x1dd0,
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0x0250,0x0650,0x0a50,0x0e50,0x1250,0x1650,0x1a50,0x1e50,
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0x02d0,0x06d0,0x0ad0,0x0ed0,0x12d0,0x16d0,0x1ad0,0x1ed0,
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0x0350,0x0750,0x0b50,0x0f50,0x1350,0x1750,0x1b50,0x1f50,
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0x03d0,0x07d0,0x0bd0,0x0fd0,0x13d0,0x17d0,0x1bd0,0x1fd0
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];
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const SCREEN_WIDTH = 280;
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const SCREEN_WIDTH_COLOR = SCREEN_WIDTH/2;
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const SCREEN_HEIGHT = 192;
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const PIXEL_BITS_PER_BYTE = 7;
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function convert_to_hires(indexes, buffer) {
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for (let y = 0; y < SCREEN_HEIGHT; ++y) {
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let hbas = OFFSETS[y];
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let hidx = y * SCREEN_WIDTH_COLOR;
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// Process two bytes at a time (20 per scan line) since pixel patterns
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// repeat every two bytes (7 color pixels).
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for (let pair = 0; pair < (SCREEN_WIDTH_COLOR / PIXEL_BITS_PER_BYTE); ++pair) {
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// Count the pixels in each "palette"; the most votes wins the byte
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let pal1 = 0; // count of "palette 1" (green/violet) pixels
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let pal2 = 0; // count of "palette 2" (orange/blue) pixels
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// Accumulate the pixel bit-pairs into accum at offset
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let accum = 0;
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let offset = 0;
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for (let pixel = 0; pixel < PIXEL_BITS_PER_BYTE; ++pixel) {
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const index = indexes[hidx++];
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let bits = 0;
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// Note that pixels are in "reverse" order
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switch (index) {
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case 0: bits = 0; break;
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case 1: bits = 2; ++pal1; break;
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case 2: bits = 1; ++pal1; break;
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case 3: bits = 3; break;
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case 4: bits = 0; break;
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case 5: bits = 2; ++pal2; break;
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case 6: bits = 1; ++pal2; break;
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case 7: bits = 3; break;
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default:
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throw new Error(`Invalid palette index: ${index} ${y}`);
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}
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accum |= ( bits << offset );
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offset += 2;
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// bits: 01234560123456
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// pixels: 00112233445566
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// NOTE: This is a poor approximation and doesn't account for white
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// emerging from any two adjacent lit bits and other NTSC fun.
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if (pixel == 3 || pixel == 6) {
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// emit byte
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let b = accum & 0x7f;
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accum >>= 7;
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offset = 1;
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if (pal2 > pal1)
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b |= 0x80;
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buffer[hbas] = b;
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hbas++;
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pal1 = 0;
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pal2 = 0;
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}
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}
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}
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}
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}
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})();
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