sgrove/learn_gamma.cljs

## learn_gamma.cljs
;; Gamma (shader-generation): https://github.com/kovasb/gamma
;; Gamma Driver (WebGL resource management, aka "Om for WebGL"): https://github.com/kovasb/gamma-driver
;; Gamma examples: https://github.com/kovasb/gamma-examples

(ns gampg.learn-gamma.lesson-01
    (: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
  "1. A triangle and a square")

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

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

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

(def program-source
  (p/program
   {:vertex-shader   {(g/gl-position)   (-> u-p-matrix
                                            (g/* u-mv-matrix)
                                            (g/* (g/vec4 a-position 1)))}
    :fragment-shader {(g/gl-frag-color) (g/vec4 1 1 1 1)}}))

(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-data [p mv vertices]
  {u-p-matrix  p
   u-mv-matrix mv
   a-position  vertices})

(defn make-driver [gl]
  (driver/basic-driver gl))

(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 main [gl node]
  (let [w                 (.-clientWidth node)
        h                 (.-clientHeight node)
        driver            (make-driver gl)
        program           (dp/program driver program-source)
        p                 (get-perspective-matrix w h)
        mv                (mat/matrix44)
        triangle-vertices [[ 0  1  0]
                           [-1 -1  0]
                           [ 1 -1  0]]
        square-vertices   [[ 1  1  0]
                           [-1  1  0]
                           [ 1 -1  0]
                           [-1 -1  0]]]
    (reset-gl-canvas! node)
    (.clearColor gl 0 0 0 1)
    (.clear gl (bit-or (.-COLOR_BUFFER_BIT gl) (.-DEPTH_BUFFER_BIT gl)))
    (let [mv (geom/translate mv [-1.5 0 -7])]
      (driver/draw-program driver program (get-data p mv triangle-vertices) {:draw-mode :triangles}))
    (let [mv (geom/translate mv [3 0 -7])]
      (driver/draw-program driver program (get-data p mv square-vertices) {:draw-mode :triangle-strip}))))

## learn_webgl_1.html
<html>
  <!-- From http://learningwebgl.com/blog/?p=3322 -->
  <head>
    <title>Learning WebGL &mdash; lesson 1</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 id="shader-fs" type="x-shader/x-fragment">
      precision mediump float;

      void main(void) {
      gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
      }
    </script>

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

      uniform mat4 uMVMatrix;
      uniform mat4 uPMatrix;

      void main(void) {
      gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
      }
    </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.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
      shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
      }


      var mvMatrix = mat4.create();
      var pMatrix = mat4.create();

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


      var triangleVertexPositionBuffer;
      var squareVertexPositionBuffer;

      function initBuffers() {
      triangleVertexPositionBuffer = gl.createBuffer();
      gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
      var vertices = [
      0.0,  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);
      triangleVertexPositionBuffer.itemSize = 3;
      triangleVertexPositionBuffer.numItems = 3;

      squareVertexPositionBuffer = gl.createBuffer();
      gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
      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);
      squareVertexPositionBuffer.itemSize = 3;
      squareVertexPositionBuffer.numItems = 4;
      }


      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);
      mat4.identity(mvMatrix);
      mat4.translate(mvMatrix, [-1.5, 0.0, -7.0]);

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

      gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems);


      mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);
      gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
      gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
      setMatrixUniforms();
      gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems);
      }


      function webGLStart() {
      var canvas = document.getElementById("lesson01-canvas");
      initGL(canvas);
      initShaders();
      initBuffers();

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

      drawScene();
      }


    </script>


  </head>


  <body onload="webGLStart();">
    <a href="http://learningwebgl.com/blog/?p=28">&lt;&lt; Back to Lesson 1</a><br />

    <canvas id="lesson01-canvas" style="border: none;" width="500" height="500"></canvas>

    <br/>
    <a href="http://learningwebgl.com/blog/?p=28">&lt;&lt; Back to Lesson 1</a><br />
  </body>

</html>
	;; Gamma (shader-generation): https://github.com/kovasb/gamma
	;; Gamma Driver (WebGL resource management, aka "Om for WebGL"): https://github.com/kovasb/gamma-driver
	;; Gamma examples: https://github.com/kovasb/gamma-examples

	(ns gampg.learn-gamma.lesson-01
	(: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
	"1. A triangle and a square")

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

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

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

	(def program-source
	(p/program
	{:vertex-shader {(g/gl-position) (-> u-p-matrix
	(g/* u-mv-matrix)
	(g/* (g/vec4 a-position 1)))}
	:fragment-shader {(g/gl-frag-color) (g/vec4 1 1 1 1)}}))

	(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-data [p mv vertices]
	{u-p-matrix p
	u-mv-matrix mv
	a-position vertices})

	(defn make-driver [gl]
	(driver/basic-driver gl))

	(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 main [gl node]
	(let [w (.-clientWidth node)
	h (.-clientHeight node)
	driver (make-driver gl)
	program (dp/program driver program-source)
	p (get-perspective-matrix w h)
	mv (mat/matrix44)
	triangle-vertices [[ 0 1 0]
	[-1 -1 0]
	[ 1 -1 0]]
	square-vertices [[ 1 1 0]
	[-1 1 0]
	[ 1 -1 0]
	[-1 -1 0]]]
	(reset-gl-canvas! node)
	(.clearColor gl 0 0 0 1)
	(.clear gl (bit-or (.-COLOR_BUFFER_BIT gl) (.-DEPTH_BUFFER_BIT gl)))
	(let [mv (geom/translate mv [-1.5 0 -7])]
	(driver/draw-program driver program (get-data p mv triangle-vertices) {:draw-mode :triangles}))
	(let [mv (geom/translate mv [3 0 -7])]
	(driver/draw-program driver program (get-data p mv square-vertices) {:draw-mode :triangle-strip}))))
	<html>
	<!-- From http://learningwebgl.com/blog/?p=3322 -->
	<head>
	<title>Learning WebGL — lesson 1</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 id="shader-fs" type="x-shader/x-fragment">
	precision mediump float;

	void main(void) {
	gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
	}
	</script>

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

	uniform mat4 uMVMatrix;
	uniform mat4 uPMatrix;

	void main(void) {
	gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
	}
	</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.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
	shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
	}


	var mvMatrix = mat4.create();
	var pMatrix = mat4.create();

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



	var triangleVertexPositionBuffer;
	var squareVertexPositionBuffer;

	function initBuffers() {
	triangleVertexPositionBuffer = gl.createBuffer();
	gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
	var vertices = [
	0.0, 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);
	triangleVertexPositionBuffer.itemSize = 3;
	triangleVertexPositionBuffer.numItems = 3;

	squareVertexPositionBuffer = gl.createBuffer();
	gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
	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);
	squareVertexPositionBuffer.itemSize = 3;
	squareVertexPositionBuffer.numItems = 4;
	}


	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);
	mat4.identity(mvMatrix);
	mat4.translate(mvMatrix, [-1.5, 0.0, -7.0]);

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

	gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems);


	mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);
	gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
	gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
	setMatrixUniforms();
	gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems);
	}



	function webGLStart() {
	var canvas = document.getElementById("lesson01-canvas");
	initGL(canvas);
	initShaders();
	initBuffers();

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

	drawScene();
	}


	</script>


	</head>


	<body onload="webGLStart();">
	<a href="http://learningwebgl.com/blog/?p=28"><< Back to Lesson 1</a><br />

	<canvas id="lesson01-canvas" style="border: none;" width="500" height="500"></canvas>

	<br/>
	<a href="http://learningwebgl.com/blog/?p=28"><< Back to Lesson 1</a><br />
	</body>

	</html>