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swannodette/learn_gamma.cljs

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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}))))
Raw
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>
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