Tutorial WebGL Sample: Unterschied zwischen den Versionen

Aktuelle Version vom 13. Dezember 2009, 13:00 Uhr

Dies ist eine Beispielanwendung zum WebGL-Tutorial. Zum Ausprobieren den Quelltext in eine Datei kopieren und mit einem WebGL-fähigen Browser öffnen. Es wird eine Textur von der URL "http://wiki.delphigl.com/wiki.png" geladen. Sollte die Anwendung nicht funktionieren, stelle sicher, dass die Textur erreichbar ist.
Das Ganze sollte ungefähr so aussehen:
<html>
    <!--
     * WebGL-Test
     * 
     * This sample is part of the WebGL Tutorial at http://delphigl.com
     *
     * Author:
     * Coolcat (Martin Weusten)
     *   see: http://wiki.delphigl.com/index.php/Benutzer:Coolcat
     *
     * Licence for this file:
     * Creative Commons Attribution 3.0 (CC-BY 3.0)
     *   see: http://creativecommons.org/licenses/by/3.0/
    -->

    <head>
        <script type="text/javascript">
            var gl = null; // our WebGL rendering context
            var viewportWidth;
            var viewportHeight;

            var program; // shader program object
            var vbo;     // vertexbufferobject
            var ibo;     // indexbufferobject
            var texture; // texture object

            function init() { 
                // request rendering context from the canvas
                // =================================================
                var canvas = document.getElementById("canvas");
                viewportWidth = canvas.width;
                viewportHeight = canvas.height;

                var names = [ "webgl", "experimental-webgl", "moz-webgl", "webkit-3d" ];
                for (var i=0; names.length>i; i++) {
                    try { 
                        gl = canvas.getContext(names[i]);
                        if (gl) { break; }
                    } catch (e) { }
                }
                if (!gl) {
                    alert("No known OpenGL context detected! Is it enabled?");
                    return;
                }
                // since WebGL is still experimental, we need some compatibility code
                compatibilityCode();

                // basic settings
                // =================================================
                gl.clearColor(0, 0, 0, 1);
                gl.enable(gl.DEPTH_TEST);

                // setup shaders
                // =================================================
                var vertexShaderSource = getShaderSource("shader-vs");
                var fragmentShaderSource = getShaderSource("shader-fs");

                var vertexShader = loadShader(gl.VERTEX_SHADER, vertexShaderSource);
                var fragmentShader = loadShader(gl.FRAGMENT_SHADER, fragmentShaderSource);
                if (!vertexShader || !fragmentShader) {
                    return;
                }

                // create program object
                program = gl.createProgram();

                // attach our two shaders to the program
                gl.attachShader(program, vertexShader);
                gl.attachShader(program, fragmentShader);

                // setup attributes (optional)
                gl.bindAttribLocation(program, 0, "aPosition");
                gl.bindAttribLocation(program, 1, "aNormal");
                gl.bindAttribLocation(program, 2, "aTexCoord");

                // linking
                gl.linkProgram(program);
                if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
                    alert(gl.getProgramInfoLog(program));
                    return;
                }

                // setup uniforms (optional)
                gl.useProgram(program);
                gl.uniform1i(gl.getUniformLocation(program, "uTexture"), 0);

                // setup VBO
                // =================================================

                // define some vertexdata
                var vertices = [
                    // position XYZ, normal XYZ, texcoord UV => 8 floats per vertex
                    -0.5,  0.5,  0.0,  0.6,  0.0,  0.8,  0.0,  0.0,
                     0.5,  0.5,  0.0,  0.6,  0.0,  0.8,  1.0,  0.0,
                    -0.5, -0.5,  0.0,  0.0,  0.0,  1.0,  0.0,  1.0,
                     0.5, -0.5,  0.0,  0.0,  0.6,  0.8,  1.0,  1.0,
                ];
                // we need also some indices because of this annoying Firefox-Bug:
                // https://bugzilla.mozilla.org/show_bug.cgi?id=521667
                var indices = [
                    0, 1, 2, 2, 1, 3
                ];
                // create VBO and IBO
                vbo = gl.createBuffer();
                gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
                gl.bufferData(gl.ARRAY_BUFFER, new WebGLFloatArray(vertices), gl.STATIC_DRAW);
                ibo = gl.createBuffer();
                gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ibo);
                gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new WebGLUnsignedShortArray(indices), gl.STATIC_DRAW);

                // create texture
                // =================================================
                texture = loadTexture("http://wiki.delphigl.com/wiki.png");

                // draw scene every 33 milliseconds
                setInterval(draw, 33);
            }

            function compatibilityCode() {
                // Firefox compatibility code
                // The WebGL*Array where named Canvas*Array in the past.
                // However, this will only affect old nightly builds. The current nightly does already
                // support the new names. (13 Dec 2009).
                try {
                    WebGLFloatArray;
                }
                catch (e) {
                    try {
                        WebGLArrayBuffer = CanvasArrayBuffer;
                        WebGLByteArray = CanvasByteArray;
                        WebGLUnsignedByteArray = CanvasUnsignedByteArray;
                        WebGLShortArray = CanvasShortArray;
                        WebGLUnsignedShortArray = CanvasUnsignedShortArray;
                        WebGLIntArray = CanvasIntArray;
                        WebGLUnsignedIntArray = CanvasUnsignedIntArray;
                        WebGLFloatArray = CanvasFloatArray;
                    }
                    catch (e) {
                        alert("Could not find Canvas array types for WebGL.");
                    }
                }

                // Google Chrome compatibility code
                // Since a JavaScript function may have multiple return types, functions 
                // 'getProgrami' and 'getShaderi' where renamed. However, Chrome does still
                // use the old names.  (30 Nov 2009)
                if (!gl.getProgramParameter) {
                    gl.getProgramParameter = gl.getProgrami;
                }
                if (!gl.getShaderParameter) {
                    gl.getShaderParameter = gl.getShaderi;
                }
            }

            function getShaderSource(id) {
                var script = document.getElementById(id);
                if (!script) { return null; }

                var source = "";
                var child = script.firstChild;
                while (child) {
                    // node is a "textnode" ?
                    if (child.nodeType == 3) {
                        source += child.textContent;
                    }
                    child = child.nextSibling;
                }
                return source;
            }

            function loadShader(shaderType, shaderSource) {
                var shader = gl.createShader(shaderType);
                if (!shader) { return null; }    
                gl.shaderSource(shader, shaderSource);
                gl.compileShader(shader);

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

                return shader;
            }

            function loadTexture(filename) {
                // preparations
                var texture = gl.createTexture();
                gl.bindTexture(gl.TEXTURE_2D, texture);
                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
                var image = new Image();

                // register event handlers
                image.onload = function() {
                    gl.bindTexture(gl.TEXTURE_2D, texture);
                    gl.texImage2D(gl.TEXTURE_2D, 0, image);
                    gl.generateMipmap(gl.TEXTURE_2D);
                    draw(); // texture now available, we can redraw the scene
                }
                image.onerror = function() {
                    alert("error while loading image '"+filename+"'.");
                }

                // request image from server
                image.src = filename; 

                // return texture object (asynchronous loading, texture NOT available yet!)
                return texture;
            }

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

                // setup shader
                gl.useProgram(program);

                // setup interleaved VBO and IBO
                gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
                gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ibo);
                gl.enableVertexAttribArray(0);
                gl.enableVertexAttribArray(1);
                gl.enableVertexAttribArray(2);
                gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 8*4, 0*4); // position
                gl.vertexAttribPointer(1, 3, gl.FLOAT, false, 8*4, 3*4); // normal
                gl.vertexAttribPointer(2, 2, gl.FLOAT, false, 8*4, 6*4); // texcoord

                // setup texture
                gl.activeTexture(gl.TEXTURE0);
                gl.bindTexture(gl.TEXTURE_2D, texture);

                // draw the buffer
                gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
            }
        </script>
 
        <script id="shader-vs" type="x-shader/x-vertex">
            attribute vec3 aPosition;
            attribute vec3 aNormal;
            attribute vec2 aTexCoord;
            varying vec3 vNormal;
            varying vec2 vTexCoord; 
            void main() {
                gl_Position = vec4(aPosition, 1.0);
                vTexCoord = aTexCoord;
                vNormal = aNormal;
            }
        </script>

        <script id="shader-fs" type="x-shader/x-fragment">
            varying vec3 vNormal;
            varying vec2 vTexCoord;
            uniform sampler2D uTexture;
            void main() {
                gl_FragColor = texture2D(uTexture, vTexCoord);
            }
        </script>
    </head>
    <body onload="init()">
        <div style="text-align: center">
            <canvas id="canvas" width="512" height="512"></canvas>
        </div>
    </body>
</html>
Tutorial WebGL Sample: Unterschied zwischen den Versionen

Aktuelle Version vom 13. Dezember 2009, 13:00 Uhr

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