webshader/shader.html at main · PackC/webshader · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>web shader</title>
	<style>
		body {
			font-family: Arial, sans-serif;
			margin: 0;
			padding: 0 0 0 10px;
			overflow: hidden;
		}
		#fps, #tick {
			position: absolute;
			left: 10px;
			top: 10px;
			font-size: 24px;
			color: white;
			background-color: rgba(0, 0, 0, 0.5);
			padding: 5px 10px;
			border-radius: 5px;
		}
		#tick {
			left: 200px;
		}
		canvas {
			border: 1px solid black;
		}
	</style>
</head>
<body>
	<div id="fps">FPS: 0</div>
	<div id="tick" class=fps >Tick: 0</div>
	<div id="info" class=fps ></div>
	<div style="height:60px;"></div>
	<canvas id="myCanvas" width="400" height="400"></canvas>
	<script>
		const canvas = document.getElementById('myCanvas');
		const ctx = canvas.getContext('2d');
		const imageData = ctx.createImageData(canvas.width, canvas.height);
		const pixel = imageData.data;

		let lastTime = 0;
		let frameCount = 0;
		let tickCount = 0;

		function dispFPS(timestamp) {
			const delta = timestamp - lastTime;
			frameCount++;
			if (delta >= 100) {
				fps0 = Math.round(frameCount*1000/delta);
				fps.textContent = `FPS: ${fps0}`;
				frameCount = 0;
				lastTime = timestamp;
			}
			tickCount ++;
			tick.textContent = `Tick: ${tickCount}`;
		}

		function setPixel(x, y, r, g, b) {
			const index = (y * imageData.width + x) * 4;
			pixel[index] = r;
			pixel[index + 1] = g;
			pixel[index + 2] = b;
			pixel[index + 3] = 255;
		}

		//uniform vec2 u_resolution; //canvas size (width,height)
		//uniform vec2 u_mouse; //mouse position in screen pixels
		//uniform float u_time; //time in seconds since load
		function drawFrame(){
			for (y = 0; y < canvas.height; y++) {
				for(x=0; x < canvas.width ;x++){
					r = x*255/400;
					g = y*255/400;
					b = Math.abs(Math.sin(tickCount/100)) * 255;
					setPixel(x,y,r,g,b);
				}
			}
			ctx.putImageData(imageData, 0, 0);
		}

		function draw(){
			ctx.clearRect(0, 0, canvas.width, canvas.height);
			drawFrame();

			ctx.fillStyle = 'blue';
			ctx.fillRect(50, 50, 100, 100);

			ctx.beginPath();
			ctx.arc(200,200, 50, 0, Math.PI * 2, true);
			ctx.fillStyle = 'red';
			ctx.fill();

			ctx.beginPath();
			ctx.moveTo(300, 50);
			ctx.lineTo(350, 150);
			ctx.strokeStyle = 'green';
			ctx.lineWidth = 5;
			ctx.stroke();

			ctx.font = '20px Arial';
			ctx.fillStyle = 'black';
			ctx.fillText('Hello, Canvas!', 100, 350);
		}

		function updateFrame(timestamp) {
			dispFPS(timestamp);
			draw();

			requestAnimationFrame(updateFrame);
		}

		updateFrame(0);
	</script>
</body>
</html>