使用Webgl创建三角形的随机位置

const canvas = document.getElementById('canvas');
const gl = canvas.getContext('webgl');

attribute vec2 a_position;

void main() {
  gl_Position = vec4(a_position, 0.0, 1.0);
}

precision mediump float;

void main() {
  gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

const positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

const positions = [
  Math.random() * 2 - 1, Math.random() * 2 - 1,
  Math.random() * 2 - 1, Math.random() * 2 - 1,
  Math.random() * 2 - 1, Math.random() * 2 - 1
];

gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);

const positionAttributeLocation = gl.getAttribLocation(program, 'a_position');
gl.enableVertexAttribArray(positionAttributeLocation);
gl.vertexAttribPointer(positionAttributeLocation, 2, gl.FLOAT, false, 0, 0);

gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);

gl.drawArrays(gl.TRIANGLES, 0, 3);