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| <!DOCTYPE html>
<html lang="en">
<head>
<title>WebGL测试</title>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
* {
margin: 0;
padding: 0;
}
html,
body,
#canvas {
width: 100%;
height: 100%;
}
#canvas {
display: block;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script id="vertex-shader-2d" type="notjs">
attribute vec4 a_position;
void main() {
gl_Position = a_position;
gl_PointSize = 5.0;
}
</script>
<script id="fragment-shader-2d" type="notjs">
precision mediump float;
void main() {
gl_FragColor = vec4(1, 0, 0.5, 1);
}
</script>
<script>
const canvas = document.querySelector("#canvas");
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
const gl = canvas.getContext("webgl");
const vertexShaderSource =
document.querySelector("#vertex-shader-2d").text;
const fragmentShaderSource = document.querySelector(
"#fragment-shader-2d"
).text;
const vertexShader = createShader(
gl,
gl.VERTEX_SHADER,
vertexShaderSource
);
const fragmentShader = createShader(
gl,
gl.FRAGMENT_SHADER,
fragmentShaderSource
);
function createShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
const success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
if (success) {
return shader;
}
console.log(gl.getShaderInfoLog(shader));
gl.deleteShader(shader);
}
function createProgram(gl, vertexShader, fragmentShader) {
const program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
const success = gl.getProgramParameter(program, gl.LINK_STATUS);
if (success) return program;
console.log(gl.getProgramInfoLog(program));
gl.deleteProgram(program);
}
const program = createProgram(gl, vertexShader, fragmentShader);
const positionAttributeLocation = gl.getAttribLocation(
program,
"a_position"
);
const positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
let positions = Array.from({ length: 2 * 60 }, () => {
return Math.random() > 0.5 ? Math.random() : -Math.random();
});
const c_positions = [];
const angle = Math.PI / 60;
const angle360 = Math.PI * 2;
let curAngle = 0;
while (curAngle < angle360) {
curAngle += angle;
c_positions.push(0.5 * Math.sin(curAngle), 0.5 * Math.cos(curAngle));
}
positions = c_positions;
const bd = new Float32Array(positions);
gl.bufferData(gl.ARRAY_BUFFER, bd, gl.STATIC_DRAW);
gl.viewport(0, 0, gl.canvas.height, gl.canvas.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.useProgram(program);
gl.enableVertexAttribArray(positionAttributeLocation);
const size = 2;
const type = gl.FLOAT;
const normalize = false;
const stride = 0;
let offset = 0;
const primitiveType = gl.POINTS;
let count = 1;
gl.vertexAttribPointer(
positionAttributeLocation,
size,
type,
normalize,
stride,
offset
);
const timer = window.setInterval(() => {
count ++;
if (count > positions.length / 2) {
window.clearInterval(timer);
return;
}
gl.drawArrays(primitiveType, offset, count);
}, 20);
</script>
</body>
</html>
|