Compare "Learn WebGL 09" with "Learn Gamma 09"

learn_gamma_09.cljs

(ns gampg.learn-gamma.lesson-09
  (:require [clojure.string :as s]
            [gamma.api :as g]
            [gamma.program :as p]
            [gamma.tools :as gt]
            [gamma-driver.drivers.basic :as driver]
            [gamma-driver.protocols :as dp]
            [goog.webgl :as ggl]
            [thi.ng.geom.core :as geom]
            [thi.ng.geom.core.matrix :as mat :refer [M44]]
            [thi.ng.geom.webgl.arrays :as arrays]))

(def title
  "9. Lots of moving objects")

(def u-p-matrix
  (g/uniform "uPMatrix" :mat4))

(def u-mv-matrix
  (g/uniform "uMVMatrix" :mat4))

(def a-position
  (g/attribute "aVertexPosition" :vec3))

(def a-vertex-normal
  (g/attribute "aVertexNormal" :vec3))

(def a-texture-coord
  (g/attribute "aTextureCoord" :vec2))

(def v-texture-coord
  (g/varying "vTextureCoord" :vec2 :mediump))

(def u-color
  (g/uniform "uColor" :vec3))

(def u-sampler
  (g/uniform "uSampler" :sampler2D))

(def program-source
  (p/program
   {:vertex-shader   {(g/gl-position)   (-> u-p-matrix
                                            (g/* u-mv-matrix)
                                            (g/* (g/vec4 a-position 1)))
                      v-texture-coord   a-texture-coord}
    :fragment-shader (let [texture-color (g/texture2D u-sampler (g/vec2 (g/swizzle v-texture-coord :st)))]
                       {(g/gl-frag-color) (g/* texture-color (g/vec4 u-color 1))})}
   {:precision {:float :mediump}}))

(defn get-perspective-matrix
  "Be sure to 
  1. pass the WIDTH and HEIGHT of the canvas *node*, not
  the GL context
  2. (set! (.-width/height canvas-node)
  width/height), respectively, or you may see no results, or strange
  results"
  [width height]
  (mat/perspective 45 (/ width height) 0.1 100))

(defn get-normal-matrix [mv]
  (-> mv
      (geom/invert)
      (geom/transpose)
      (mat/matrix44->matrix33)))

(defn get-data [p mv vertices texture texture-coords color]
  {u-p-matrix      p
   u-mv-matrix     mv
   u-color         color
   u-sampler       texture
   a-position      vertices
   a-texture-coord texture-coords})

(defn reset-gl-canvas! [canvas-node]
  (let [gl     (.getContext canvas-node "webgl")
        width  (.-clientWidth canvas-node)
        height (.-clientHeight canvas-node)]
    ;; Set the width/height (in terms of GL-resolution) to actual
    ;; canvas-element width/height (or else you'll see blurry results)
    (set! (.-width canvas-node) width)
    (set! (.-height canvas-node) height)
    ;; Setup GL Canvas
    (.viewport gl 0 0 width height)))

(defn random-color []
  [(js/Math.random) (js/Math.random) (js/Math.random)])

(defn make-star [star-count idx]
  {:distance       (* (/ idx star-count) 5)
   :rotation-speed (/ idx star-count 10)
   :angle          0
   :color          (random-color)
   :twinkle        (random-color)})

;; js/window.requestAnimationFrame doesn't take arguments, so we have
;; to store the state elsewhere - in this atom, for example.
(defn app-state [width height]
  (let [star-count 50]
    {:last-rendered (.getTime (js/Date.))
     :scene         {:stars (map (partial make-star star-count) (range star-count))
                     :star-vertices [[-1.0, -1.0,  0.0,]
                                     [1.0, -1.0,  0.0,]
                                     [-1.0,  1.0,  0.0,]
                                     [1.0,  1.0,  0.0]]
                     :star-texture-coords [0.0, 0.0,
                                           1.0, 0.0,
                                           0.0, 1.0,
                                           1.0, 1.0]
                     :mv    (mat/matrix44)
                     :p     (get-perspective-matrix width height)}}))

(defn draw-fn [gl driver program]
  (fn [state]
    (.clear gl (bit-or (.-COLOR_BUFFER_BIT gl) (.-DEPTH_BUFFER_BIT gl)))
    (let [{:keys [p mv texture
                  stars star-vertices
                  star-texture-coords]} (:scene state)
                  time-now     (.getTime (js/Date.))
                  twinkle? (pos? (js/Math.sin (/ time-now 1000)))]
      (doseq [star stars]
        (let [mv (-> mv
                     (geom/translate [0 0 -7])
                     (geom/rotate-around-axis [0 0 1] (:angle star))
                     (geom/translate [(:distance star) 0 -7])
                     (geom/rotate-around-axis [0 0 -1] (- (:angle star))))]
          (driver/draw-program driver program
                               (get-data p mv star-vertices texture star-texture-coords (if twinkle?
                                                                                          (:twinkle star)
                                                                                          (:color star)))
                               {:draw-mode :triangle-strip}))))))  

(defn animate [draw-fn step-fn current-value]
  (js/requestAnimationFrame
   (fn [time]
     (let [next-value (step-fn time current-value)]
       (draw-fn next-value)
       (animate draw-fn step-fn next-value)))))

(def effective-fpms
  (/ 60 1000))

(defn move-star [elapsed star]
  (let [distance  (- (:distance star)
                     (* effective-fpms elapsed 0.01))
        reset   (if (pos? distance) 0 5)]
    (-> star
        (assoc-in [:distance] (+ distance reset))
        (update-in [:angle] + (* (:rotation-speed star))))))

(defn tick
  "Takes the old world value and produces a new world value, suitable
  for rendering"
  [time state]
  ;; We get the elapsed time since the last render to compensate for
  ;; lag, etc.
  (let [time-now  (.getTime (js/Date.))
        elapsed   (- time-now (:last-rendered state))
        cube-diff (/ (* 75 elapsed) 100000)]
    (-> state
        ;; This is painful at 60FPS. Transducers?
        (update-in [:scene :stars] (fn [stars] (mapv (partial move-star elapsed) stars)))
        (assoc-in [:last-rendered] time-now))))

(defn main [gl node]  
  (let [width   (.-clientWidth node)
        height  (.-clientHeight node)
        driver  (driver/basic-driver gl)
        program (dp/program driver program-source)
        state   (app-state width height)]
    (reset-gl-canvas! node)
    ;; Set the blending function
    (.blendFunc gl (.-SRC_ALPHA gl) (.-ONE gl))
    (.enable gl (.-BLEND gl))
    (.disable gl (.-DEPTH_TEST gl))
    (.clearColor gl 0 0 0 1)
    (.clear gl (bit-or (.-COLOR_BUFFER_BIT gl) (.-DEPTH_BUFFER_BIT gl)))
    (let [image (js/Image.)]
      (aset image "onload"
            (fn [] (let [texture {:data {:data       image
                                        :filter     {:min :linear
                                                     :mag :nearest}
                                        :flip-y     true
                                        :texture-id 0}}]
                    (animate (draw-fn gl driver program) tick (assoc-in state [:scene :texture] texture)))))
      (aset image "src" "/images/star.gif"))))

learn_webgl_09.html

<html>

<head>
<title>Learning WebGL &mdash; lesson 9</title>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">

<script type="text/javascript" src="glMatrix-0.9.5.min.js"></script>
<script type="text/javascript" src="webgl-utils.js"></script>

<script id="shader-fs" type="x-shader/x-fragment">
    precision mediump float;

    varying vec2 vTextureCoord;

    uniform sampler2D uSampler;

    uniform vec3 uColor;

    void main(void) {
        vec4 textureColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
        gl_FragColor = textureColor * vec4(uColor, 1.0);
    }
</script>

<script id="shader-vs" type="x-shader/x-vertex">
    attribute vec3 aVertexPosition;
    attribute vec2 aTextureCoord;

    uniform mat4 uMVMatrix;
    uniform mat4 uPMatrix;

    varying vec2 vTextureCoord;

    void main(void) {
        gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
        vTextureCoord = aTextureCoord;
    }
</script>


<script type="text/javascript">

    var gl;

    function initGL(canvas) {
        try {
            gl = canvas.getContext("experimental-webgl");
            gl.viewportWidth = canvas.width;
            gl.viewportHeight = canvas.height;
        } catch (e) {
        }
        if (!gl) {
            alert("Could not initialise WebGL, sorry :-(");
        }
    }


    function getShader(gl, id) {
        var shaderScript = document.getElementById(id);
        if (!shaderScript) {
            return null;
        }

        var str = "";
        var k = shaderScript.firstChild;
        while (k) {
            if (k.nodeType == 3) {
                str += k.textContent;
            }
            k = k.nextSibling;
        }

        var shader;
        if (shaderScript.type == "x-shader/x-fragment") {
            shader = gl.createShader(gl.FRAGMENT_SHADER);
        } else if (shaderScript.type == "x-shader/x-vertex") {
            shader = gl.createShader(gl.VERTEX_SHADER);
        } else {
            return null;
        }

        gl.shaderSource(shader, str);
        gl.compileShader(shader);

        if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
            alert(gl.getShaderInfoLog(shader));
            return null;
        }

        return shader;
    }


    var shaderProgram;

    function initShaders() {
        var fragmentShader = getShader(gl, "shader-fs");
        var vertexShader = getShader(gl, "shader-vs");

        shaderProgram = gl.createProgram();
        gl.attachShader(shaderProgram, vertexShader);
        gl.attachShader(shaderProgram, fragmentShader);
        gl.linkProgram(shaderProgram);

        if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
            alert("Could not initialise shaders");
        }

        gl.useProgram(shaderProgram);

        shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
        gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

        shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
        gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);

        shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
        shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
        shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
        shaderProgram.colorUniform = gl.getUniformLocation(shaderProgram, "uColor");
    }


    function handleLoadedTexture(texture) {
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
        gl.bindTexture(gl.TEXTURE_2D, texture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.image);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

        gl.bindTexture(gl.TEXTURE_2D, null);
    }


    var starTexture;

    function initTexture() {
        starTexture = gl.createTexture();
        starTexture.image = new Image();
        starTexture.image.onload = function () {
            handleLoadedTexture(starTexture)
        }

        starTexture.image.src = "star.gif";
    }


    var mvMatrix = mat4.create();
    var mvMatrixStack = [];
    var pMatrix = mat4.create();

    function mvPushMatrix() {
        var copy = mat4.create();
        mat4.set(mvMatrix, copy);
        mvMatrixStack.push(copy);
    }

    function mvPopMatrix() {
        if (mvMatrixStack.length == 0) {
            throw "Invalid popMatrix!";
        }
        mvMatrix = mvMatrixStack.pop();
    }


    function setMatrixUniforms() {
        gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
        gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
    }


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


    var currentlyPressedKeys = {};

    function handleKeyDown(event) {
        currentlyPressedKeys[event.keyCode] = true;
    }


    function handleKeyUp(event) {
        currentlyPressedKeys[event.keyCode] = false;
    }


    var zoom = -15;


    var tilt = 90;
    var spin = 0;


    function handleKeys() {
        if (currentlyPressedKeys[33]) {
            // Page Up
            zoom -= 0.1;
        }
        if (currentlyPressedKeys[34]) {
            // Page Down
            zoom += 0.1;
        }
        if (currentlyPressedKeys[38]) {
            // Up cursor key
            tilt += 2;
        }
        if (currentlyPressedKeys[40]) {
            // Down cursor key
            tilt -= 2;
        }
    }


    var starVertexPositionBuffer;
    var starVertexTextureCoordBuffer;

    function initBuffers() {
        starVertexPositionBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, starVertexPositionBuffer);
        vertices = [
            -1.0, -1.0,  0.0,
             1.0, -1.0,  0.0,
            -1.0,  1.0,  0.0,
             1.0,  1.0,  0.0
        ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
        starVertexPositionBuffer.itemSize = 3;
        starVertexPositionBuffer.numItems = 4;

        starVertexTextureCoordBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, starVertexTextureCoordBuffer);
        var textureCoords = [
            0.0, 0.0,
            1.0, 0.0,
            0.0, 1.0,
            1.0, 1.0
        ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
        starVertexTextureCoordBuffer.itemSize = 2;
        starVertexTextureCoordBuffer.numItems = 4;
    }


    function drawStar() {
        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, starTexture);
        gl.uniform1i(shaderProgram.samplerUniform, 0);

        gl.bindBuffer(gl.ARRAY_BUFFER, starVertexTextureCoordBuffer);
        gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, starVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

        gl.bindBuffer(gl.ARRAY_BUFFER, starVertexPositionBuffer);
        gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, starVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

        setMatrixUniforms();
        gl.drawArrays(gl.TRIANGLE_STRIP, 0, starVertexPositionBuffer.numItems);
    }



    function Star(startingDistance, rotationSpeed) {
        this.angle = 0;
        this.dist = startingDistance;
        this.rotationSpeed = rotationSpeed;

        // Set the colors to a starting value.
        this.randomiseColors();
    }

    Star.prototype.draw = function (tilt, spin, twinkle) {
        mvPushMatrix();

        // Move to the star's position
        mat4.rotate(mvMatrix, degToRad(this.angle), [0.0, 1.0, 0.0]);
        mat4.translate(mvMatrix, [this.dist, 0.0, 0.0]);

        // Rotate back so that the star is facing the viewer
        mat4.rotate(mvMatrix, degToRad(-this.angle), [0.0, 1.0, 0.0]);
        mat4.rotate(mvMatrix, degToRad(-tilt), [1.0, 0.0, 0.0]);

        if (twinkle) {
            // Draw a non-rotating star in the alternate "twinkling" color
            gl.uniform3f(shaderProgram.colorUniform, this.twinkleR, this.twinkleG, this.twinkleB);
            drawStar();
        }

        // All stars spin around the Z axis at the same rate
        mat4.rotate(mvMatrix, degToRad(spin), [0.0, 0.0, 1.0]);

        // Draw the star in its main color
        gl.uniform3f(shaderProgram.colorUniform, this.r, this.g, this.b);
        drawStar()

        mvPopMatrix();
    };


    var effectiveFPMS = 60 / 1000;
    Star.prototype.animate = function (elapsedTime) {
        this.angle += this.rotationSpeed * effectiveFPMS * elapsedTime;

        // Decrease the distance, resetting the star to the outside of
        // the spiral if it's at the center.
        this.dist -= 0.01 * effectiveFPMS * elapsedTime;
        if (this.dist < 0.0) {
            this.dist += 5.0;
            this.randomiseColors();
        }

    };


    Star.prototype.randomiseColors = function () {
        // Give the star a random color for normal
        // circumstances...
        this.r = Math.random();
        this.g = Math.random();
        this.b = Math.random();

        // When the star is twinkling, we draw it twice, once
        // in the color below (not spinning) and then once in the
        // main color defined above.
        this.twinkleR = Math.random();
        this.twinkleG = Math.random();
        this.twinkleB = Math.random();
    };



    var stars = [];

    function initWorldObjects() {
        var numStars = 50;

        for (var i=0; i < numStars; i++) {
            stars.push(new Star((i / numStars) * 5.0, i / numStars));
        }
    }


    function drawScene() {
        gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        mat4.perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0, pMatrix);

        gl.blendFunc(gl.SRC_ALPHA, gl.ONE);
        gl.enable(gl.BLEND);

        mat4.identity(mvMatrix);
        mat4.translate(mvMatrix, [0.0, 0.0, zoom]);
        mat4.rotate(mvMatrix, degToRad(tilt), [1.0, 0.0, 0.0]);

        var twinkle = document.getElementById("twinkle").checked;
        for (var i in stars) {
            stars[i].draw(tilt, spin, twinkle);
            spin += 0.1;
        }

    }


    var lastTime = 0;

    function animate() {
        var timeNow = new Date().getTime();
        if (lastTime != 0) {
            var elapsed = timeNow - lastTime;

            for (var i in stars) {
                stars[i].animate(elapsed);
            }
        }
        lastTime = timeNow;

    }


    function tick() {
        requestAnimFrame(tick);
        handleKeys();
        drawScene();
        animate();
    }



    function webGLStart() {
        var canvas = document.getElementById("lesson09-canvas");
        initGL(canvas);
        initShaders();
        initBuffers();
        initTexture();
        initWorldObjects();

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

        document.onkeydown = handleKeyDown;
        document.onkeyup = handleKeyUp;

        tick();
    }

</script>


</head>


<body onload="webGLStart();">
    <a href="http://learningwebgl.com/blog/?p=1008">&lt;&lt; Back to Lesson 9</a><br />

    <canvas id="lesson09-canvas" style="border: none;" width="500" height="500"></canvas>

    <br/>
    <input type="checkbox" id="twinkle" /> Twinkle<br/>
    (Use up/down cursor keys to rotate, and <code>Page Up</code>/<code>Page Down</code> to zoom out/in)

    <br/>
    <br/>
    <a href="http://learningwebgl.com/blog/?p=1008">&lt;&lt; Back to Lesson 9</a>
</body>

</html>