WebGL - 3D Camera Look At

by dustinkerstein

HTML

<canvas id="canvas"></canvas>
<div id="uiContainer">
  <div id="ui">
    <div id="cameraAngle"></div>
  </div>
</div>
<!-- vertex shader -->
<script  id="vertex-shader-3d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec4 a_color;

uniform mat4 u_matrix;

varying vec4 v_color;

void main() {
  // Multiply the position by the matrix.
  gl_Position = u_matrix * a_position;

  // Pass the color to the fragment shader.
  v_color = a_color;
}
</script>
<!-- fragment shader -->
<script  id="fragment-shader-3d" type="x-shader/x-fragment">
precision mediump float;

// Passed in from the vertex shader.
varying vec4 v_color;

void main() {
   gl_FragColor = v_color;
}
</script><!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="https://webglfundamentals.org/webgl/resources/webgl-utils.js"></script>
<script src="https://webglfundamentals.org/webgl/resources/webgl-lessons-ui.js"></script>

CSS

@import url("https://webglfundamentals.org/webgl/resources/webgl-tutorials.css");
body {
  margin: 0;
}
canvas {
  width: 100vw;
  height: 100vh;
  display: block;
}

JavaScript

// WebGL - 3D Camera Look At
// from https://webglfundamentals.org/webgl/webgl-3d-camera-look-at.html

"use strict";

function main() {
  // Get A WebGL context
  /** @type {HTMLCanvasElement} */
  var canvas = document.querySelector("#canvas");
  var gl = canvas.getContext("webgl");
  if (!gl) {
    return;
  }

  // setup GLSL program
  var program = webglUtils.createProgramFromScripts(gl, ["vertex-shader-3d", "fragment-shader-3d"]);

  // look up where the vertex data needs to go.
  var positionLocation = gl.getAttribLocation(program, "a_position");
  var colorLocation = gl.getAttribLocation(program, "a_color");

  // lookup uniforms
  var matrixLocation = gl.getUniformLocation(program, "u_matrix");

  // Create a buffer to put positions in
  var positionBuffer = gl.createBuffer();
  // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
  gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
  // Put geometry data into buffer
  setGeometry(gl);

  // Create a buffer to put colors in
  var colorBuffer = gl.createBuffer();
  // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = colorBuffer)
  gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
  // Put color data into buffer
  setColors(gl);

  function radToDeg(r) {
    return r * 180 / Math.PI;
  }

  function degToRad(d) {
    return d * Math.PI / 180;
  }

  var cameraAngleRadians = degToRad(0);
  var fieldOfViewRadians = degToRad(60);

  drawScene();

  // Setup a ui.
  webglLessonsUI.setupSlider("#cameraAngle", {value: radToDeg(cameraAngleRadians), slide: updateCameraAngle, min: -360, max: 360});
  function updateCameraAngle(event, ui) {
    cameraAngleRadians = degToRad(ui.value);
    drawScene();
  }

  // Draw the scene.
  function drawScene() {
  	window.requestAnimationFrame(drawScene);

  	cameraAngleRadians = (cameraAngleRadians + .01) % Math.PI;
    webglUtils.resizeCanvasToDisplaySize(gl.canvas);

    // Tell WebGL how to convert from clip space to pixels
    gl.viewport(0, 0,...