adapt simple embedding example

(bring your own smb.nes)
This commit is contained in:
Jeremy Penner 2024-10-29 21:20:35 -04:00
parent 34e0367dff
commit c29f364957
3 changed files with 152 additions and 1 deletions

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.gitignore vendored
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.direnv .direnv
smb.nes

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index.html Normal file
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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Embedding Example</title>
<script type="text/javascript" src="jsnes/dist/jsnes.js"></script>
<script type="text/javascript" src="nes-embed.js"></script>
</head>
<body>
<div style="margin: auto; max-height: 75vh; aspect-ratio: 4 / 3;">
<canvas id="nes-canvas" width="256" height="240" style="width: 100%; max-height: 75vh; image-rendering: pixelated; aspect-ratio: 4 / 3;"/>
</div>
<button onclick="nes_load_url('nes-canvas', 'smb.nes')">Start!</button>
<p>DPad: Arrow keys<br/>B button: Z, A button: X, Select: Tab / C, Start: Return / V</p>
</body>
</html>

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nes-embed.js Normal file
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var SCREEN_WIDTH = 256;
var SCREEN_HEIGHT = 240;
var FRAMEBUFFER_SIZE = SCREEN_WIDTH*SCREEN_HEIGHT;
var canvas_ctx, image;
var framebuffer_u8, framebuffer_u32;
var AUDIO_BUFFERING = 512;
var SAMPLE_COUNT = 4*1024;
var SAMPLE_MASK = SAMPLE_COUNT - 1;
var audio_samples_L = new Float32Array(SAMPLE_COUNT);
var audio_samples_R = new Float32Array(SAMPLE_COUNT);
var audio_write_cursor = 0, audio_read_cursor = 0;
var nes = new jsnes.NES({
onFrame: function(framebuffer_24){
for(var i = 0; i < FRAMEBUFFER_SIZE; i++) framebuffer_u32[i] = 0xFF000000 | framebuffer_24[i];
},
onAudioSample: function(l, r){
audio_samples_L[audio_write_cursor] = l;
audio_samples_R[audio_write_cursor] = r;
audio_write_cursor = (audio_write_cursor + 1) & SAMPLE_MASK;
},
});
function onAnimationFrame(){
window.requestAnimationFrame(onAnimationFrame);
image.data.set(framebuffer_u8);
canvas_ctx.putImageData(image, 0, 0);
}
function audio_remain(){
return (audio_write_cursor - audio_read_cursor) & SAMPLE_MASK;
}
function audio_callback(event){
var dst = event.outputBuffer;
var len = dst.length;
// Attempt to avoid buffer underruns.
if(audio_remain() < AUDIO_BUFFERING) nes.frame();
var dst_l = dst.getChannelData(0);
var dst_r = dst.getChannelData(1);
for(var i = 0; i < len; i++){
var src_idx = (audio_read_cursor + i) & SAMPLE_MASK;
dst_l[i] = audio_samples_L[src_idx];
dst_r[i] = audio_samples_R[src_idx];
}
audio_read_cursor = (audio_read_cursor + len) & SAMPLE_MASK;
}
const KEY_MAPPINGS = [{
"ArrowUp": "BUTTON_UP",
"ArrowDown": "BUTTON_DOWN",
"ArrowLeft": "BUTTON_LEFT",
"ArrowRight": "BUTTON_RIGHT",
"KeyZ": "BUTTON_B",
"KeyX": "BUTTON_A",
"KeyC": "BUTTON_SELECT",
"KeyV": "BUTTON_START",
"Enter": "BUTTON_START",
"Tab": "BUTTON_SELECT"
}]
function keyboard(callback, event){
var player = 1;
for (const mapping of KEY_MAPPINGS) {
const button = mapping[event.code];
if (button) {
callback(player, jsnes.Controller[button]);
event.preventDefault();
}
player ++;
}
}
function nes_init(canvas_id){
var canvas = document.getElementById(canvas_id);
canvas_ctx = canvas.getContext("2d");
image = canvas_ctx.getImageData(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
canvas_ctx.fillStyle = "black";
canvas_ctx.fillRect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
// Allocate framebuffer array.
var buffer = new ArrayBuffer(image.data.length);
framebuffer_u8 = new Uint8ClampedArray(buffer);
framebuffer_u32 = new Uint32Array(buffer);
// Setup audio.
var audio_ctx = new window.AudioContext();
var script_processor = audio_ctx.createScriptProcessor(AUDIO_BUFFERING, 0, 2);
script_processor.onaudioprocess = audio_callback;
script_processor.connect(audio_ctx.destination);
}
function nes_boot(rom_data){
nes.loadROM(rom_data);
window.requestAnimationFrame(onAnimationFrame);
}
function nes_load_data(canvas_id, rom_data){
nes_init(canvas_id);
nes_boot(rom_data);
}
function nes_load_url(canvas_id, path){
nes_init(canvas_id);
var req = new XMLHttpRequest();
req.open("GET", path);
req.overrideMimeType("text/plain; charset=x-user-defined");
req.onerror = () => console.log(`Error loading ${path}: ${req.statusText}`);
req.onload = function() {
if (this.status === 200) {
nes_boot(this.responseText);
} else if (this.status === 0) {
// Aborted, so ignore error
} else {
req.onerror();
}
};
req.send();
}
document.addEventListener('keydown', (event) => {keyboard(nes.buttonDown, event)});
document.addEventListener('keyup', (event) => {keyboard(nes.buttonUp, event)});