generalWorkflow.js

function main() {
  // Create a buffer and put three 2d clip space points in it
  var positionBuffer = gl.createBuffer();

  // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
  gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

  var positions = [0, 0, 0, 0.5, 0.7, 0];
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);

  // Create a vertex array object (attribute state)
  var vao = gl.createVertexArray();

  // and make it the one we're currently working with
  gl.bindVertexArray(vao);

  // Turn on the attribute
  gl.enableVertexAttribArray(positionAttributeLocation);

  // Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
  var size = 2; // 2 components per iteration
  var type = gl.FLOAT; // the data is 32bit floats
  var normalize = false; // don't normalize the data
  var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
  var offset = 0; // start at the beginning of the buffer
  gl.vertexAttribPointer(
    positionAttributeLocation,
    size,
    type,
    normalize,
    stride,
    offset,
  );

  webglUtils.resizeCanvasToDisplaySize(gl.canvas);

  // Tell WebGL how to convert from clip space to pixels
  gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

  // Clear the canvas
  gl.clearColor(0, 0, 0, 0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  // Tell it to use our program (pair of shaders)
  gl.useProgram(program);

  // Bind the attribute/buffer set we want.
  gl.bindVertexArray(vao);

  // draw
  var primitiveType = gl.TRIANGLES;
  var offset = 0;
  var count = 3;
  gl.drawArrays(primitiveType, offset, count);
}

main();