- Qt 5.5
- Qt Canvas 3D
- Lit and Textured Cube Example
- textureandlight.js Example File
- Qt 5.5.1 Reference Documentation

# textureandlight.js Example File

canvas3d/textureandlight/qml/textureandlight/textureandlight.js

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the QtCanvas3D module of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL3$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
    ** Software or, alternatively, in accordance with the terms contained in
    ** a written agreement between you and The Qt Company. For licensing terms
    ** and conditions see http://www.qt.io/terms-conditions. For further
    ** information use the contact form at http://www.qt.io/contact-us.
    **
    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 3 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.LGPLv3 included in the
    ** packaging of this file. Please review the following information to
    ** ensure the GNU Lesser General Public License version 3 requirements
    ** will be met: https://www.gnu.org/licenses/lgpl.html.
    **
    ** GNU General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU
    ** General Public License version 2.0 or later as published by the Free
    ** Software Foundation and appearing in the file LICENSE.GPL included in
    ** the packaging of this file. Please review the following information to
    ** ensure the GNU General Public License version 2.0 requirements will be
    ** met: http://www.gnu.org/licenses/gpl-2.0.html.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    Qt.include("gl-matrix.js")

    //
    // Draws a cube that has the Qt logo as decal texture on each face.
    // A simple per vertex lighting equation is used to emulate light landing on the rotating cube.
    //

    var gl;
    var cubeTexture = 0;
    var vertexPositionAttribute;
    var textureCoordAttribute;
    var vertexNormalAttribute;
    var mvMatrix = mat4.create();
    var pMatrix  = mat4.create();
    var nMatrix  = mat4.create();
    var pMatrixUniform;
    var mvMatrixUniform;
    var nUniform;
    var width = 0;
    var height = 0;
    var canvas3d;
    var pixelSize;

    function initializeGL(canvas) {
        canvas3d = canvas;
        // Get the OpenGL context object that represents the API we call
        gl = canvas.getContext("canvas3d", {depth:true, antialias:true});

        // Setup the OpenGL state
        gl.enable(gl.DEPTH_TEST);
        gl.depthFunc(gl.LESS);
        gl.enable(gl.CULL_FACE);
        gl.cullFace(gl.BACK);
        gl.clearColor(0.98, 0.98, 0.98, 1.0);
        gl.clearDepth(1.0);
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

        // Set viewport
        gl.viewport(0, 0, canvas.width, canvas.height);

        // Initialize the shader program
        initShaders();

        // Initialize vertex and color buffers
        initBuffers();

        // Load the textures
        var qtLogoImage = TextureImageFactory.newTexImage();
        qtLogoImage.imageLoaded.connect(function() {
            console.log("Texture loaded, "+qtLogoImage.src);
            // Create the Canvas3DTexture object
            cubeTexture = gl.createTexture();
            // Bind it
            gl.bindTexture(gl.TEXTURE_2D, cubeTexture);
            // Set the properties
            gl.texImage2D(gl.TEXTURE_2D,    // target
                          0,                // level
                          gl.RGBA,          // internalformat
                          gl.RGBA,          // format
                          gl.UNSIGNED_BYTE, // type
                          qtLogoImage);     // pixels
            // Set texture filtering parameters
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
            // Generate mipmap
            gl.generateMipmap(gl.TEXTURE_2D);
        });
        qtLogoImage.imageLoadingFailed.connect(function() {
            console.log("Texture load FAILED, "+qtLogoImage.errorString);
        });
        qtLogoImage.src = "qrc:/qtlogo.png";
    }

    function resizeGL(canvas)
    {
        var pixelRatio = canvas.devicePixelRatio;
        canvas.pixelSize = Qt.size(canvas.width * pixelRatio,
                                   canvas.height * pixelRatio);
    }

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

    function paintGL(canvas) {
        var pixelRatio = canvas.devicePixelRatio;
        var currentWidth = canvas.width * pixelRatio;
        var currentHeight = canvas.height * pixelRatio;
        if (currentWidth !== width || currentHeight !== height ) {
            width = currentWidth;
            height = currentHeight;
            gl.viewport(0, 0, width, height);
            mat4.perspective(pMatrix, degToRad(45), width / height, 0.1, 500.0);
            gl.uniformMatrix4fv(pMatrixUniform, false, pMatrix);
        }

        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        mat4.identity(mvMatrix);
        mat4.translate(mvMatrix, mvMatrix, [(canvas.yRotAnim - 120.0) / 120.0,
                                            (canvas.xRotAnim -  60.0) / 50.0,
                                            -10.0]);
        mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.xRotAnim), [0, 1, 0]);
        mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.yRotAnim), [1, 0, 0]);
        mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.zRotAnim), [0, 0, 1]);
        gl.uniformMatrix4fv(mvMatrixUniform, false, mvMatrix);

        mat4.invert(nMatrix, mvMatrix);
        mat4.transpose(nMatrix, nMatrix);
        gl.uniformMatrix4fv(nUniform, false, nMatrix);

        gl.drawElements(gl.TRIANGLES, 36, gl.UNSIGNED_SHORT, 0);
    }

    function initBuffers()
    {
        var cubeVertexPositionBuffer = gl.createBuffer();
        cubeVertexPositionBuffer.name = "cubeVertexPositionBuffer";
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
        gl.bufferData(
                    gl.ARRAY_BUFFER,
                    new Float32Array([// Front face
                                            -1.0, -1.0,  1.0,
                                            1.0, -1.0,  1.0,
                                            1.0,  1.0,  1.0,
                                            -1.0,  1.0,  1.0,

                                            // Back face
                                            -1.0, -1.0, -1.0,
                                            -1.0,  1.0, -1.0,
                                            1.0,  1.0, -1.0,
                                            1.0, -1.0, -1.0,

                                            // Top face
                                            -1.0,  1.0, -1.0,
                                            -1.0,  1.0,  1.0,
                                            1.0,  1.0,  1.0,
                                            1.0,  1.0, -1.0,

                                            // Bottom face
                                            -1.0, -1.0, -1.0,
                                            1.0, -1.0, -1.0,
                                            1.0, -1.0,  1.0,
                                            -1.0, -1.0,  1.0,

                                            // Right face
                                            1.0, -1.0, -1.0,
                                            1.0,  1.0, -1.0,
                                            1.0,  1.0,  1.0,
                                            1.0, -1.0,  1.0,

                                            // Left face
                                            -1.0, -1.0, -1.0,
                                            -1.0, -1.0,  1.0,
                                            -1.0,  1.0,  1.0,
                                            -1.0,  1.0, -1.0
                                           ]),
                    gl.STATIC_DRAW);
        gl.vertexAttribPointer(vertexPositionAttribute, 3, gl.FLOAT, false, 0, 0);

        var cubeVertexIndexBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
                      new Uint16Array([
                                                0,  1,  2,      0,  2,  3,    // front
                                                4,  5,  6,      4,  6,  7,    // back
                                                8,  9,  10,     8,  10, 11,   // top
                                                12, 13, 14,     12, 14, 15,   // bottom
                                                16, 17, 18,     16, 18, 19,   // right
                                                20, 21, 22,     20, 22, 23    // left
                                            ]),
                      gl.STATIC_DRAW);

        var cubeVerticesTextureCoordBuffer = gl.createBuffer();
        cubeVerticesTextureCoordBuffer.name = "cubeVerticesTextureCoordBuffer";
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVerticesTextureCoordBuffer);
        var textureCoordinates = [
                    // Front
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0,
                    // Back
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0,
                    // Top
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0,
                    // Bottom
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0,
                    // Right
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0,
                    // Left
                    1.0,  0.0,
                    0.0,  0.0,
                    0.0,  1.0,
                    1.0,  1.0
                ];
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoordinates),
                      gl.STATIC_DRAW);
        gl.vertexAttribPointer(textureCoordAttribute, 2, gl.FLOAT, false, 0, 0);

        var cubeVerticesNormalBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVerticesNormalBuffer);
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
                                                                  // Front
                                                                  0.0,  0.0,  1.0,
                                                                  0.0,  0.0,  1.0,
                                                                  0.0,  0.0,  1.0,
                                                                  0.0,  0.0,  1.0,

                                                                  // Back
                                                                  0.0,  0.0, -1.0,
                                                                  0.0,  0.0, -1.0,
                                                                  0.0,  0.0, -1.0,
                                                                  0.0,  0.0, -1.0,

                                                                  // Top
                                                                  0.0,  1.0,  0.0,
                                                                  0.0,  1.0,  0.0,
                                                                  0.0,  1.0,  0.0,
                                                                  0.0,  1.0,  0.0,

                                                                  // Bottom
                                                                  0.0, -1.0,  0.0,
                                                                  0.0, -1.0,  0.0,
                                                                  0.0, -1.0,  0.0,
                                                                  0.0, -1.0,  0.0,

                                                                  // Right
                                                                  1.0,  0.0,  0.0,
                                                                  1.0,  0.0,  0.0,
                                                                  1.0,  0.0,  0.0,
                                                                  1.0,  0.0,  0.0,

                                                                  // Left
                                                                  -1.0,  0.0,  0.0,
                                                                  -1.0,  0.0,  0.0,
                                                                  -1.0,  0.0,  0.0,
                                                                  -1.0,  0.0,  0.0
                                                              ]), gl.STATIC_DRAW);
        gl.vertexAttribPointer(vertexNormalAttribute, 3, gl.FLOAT, false, 0, 0);
    }

    function initShaders()
    {
        var vertexShader = getShader(gl,
                                     "attribute highp vec3 aVertexNormal;    \
                                      attribute highp vec3 aVertexPosition;  \
                                      attribute highp vec2 aTextureCoord;    \
                                                                             \
                                      uniform highp mat4 uNormalMatrix;      \
                                      uniform mat4 uMVMatrix;                \
                                      uniform mat4 uPMatrix;                 \
                                                                             \
                                      varying mediump vec4 vColor;           \
                                      varying highp vec2 vTextureCoord;      \
                                      varying highp vec3 vLighting;          \
                                                                             \
                                      void main(void) {                      \
                                          gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0); \
                                          vTextureCoord = aTextureCoord;                                   \
                                          highp vec3 ambientLight = vec3(0.5, 0.5, 0.5);                   \
                                          highp vec3 directionalLightColor = vec3(0.75, 0.75, 0.75);       \
                                          highp vec3 directionalVector = vec3(0.85, 0.8, 0.75);            \
                                          highp vec4 transformedNormal = uNormalMatrix * vec4(aVertexNormal, 1.0); \
                                          highp float directional = max(dot(transformedNormal.xyz, directionalVector), 0.0); \
                                          vLighting = ambientLight + (directionalLightColor * directional); \
                                      }", gl.VERTEX_SHADER);
        var fragmentShader = getShader(gl,
                                       "varying highp vec2 vTextureCoord;  \
                                        varying highp vec3 vLighting;      \
                                                                           \
                                        uniform sampler2D uSampler;        \
                                                                           \
                                        void main(void) {                  \
                                            mediump vec3 texelColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t)).rgb; \
                                            gl_FragColor = vec4(texelColor * vLighting, 1.0);                                      \
                                        }", gl.FRAGMENT_SHADER);
        // Create the Canvas3DProgram for shader
        var shaderProgram = gl.createProgram();

        // Attach the shader sources to the shader program
        gl.attachShader(shaderProgram, vertexShader);
        gl.attachShader(shaderProgram, fragmentShader);

        // Link the program
        gl.linkProgram(shaderProgram);

        // Check the linking status
        if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
            console.log("Could not initialise shaders");
            console.log(gl.getProgramInfoLog(shaderProgram));
        }

        // Take the shader program into use
        gl.useProgram(shaderProgram);

        // Look up where the vertex data needs to go
        vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
        gl.enableVertexAttribArray(vertexPositionAttribute);
        textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
        gl.enableVertexAttribArray(textureCoordAttribute);
        vertexNormalAttribute = gl.getAttribLocation(shaderProgram, "aVertexNormal");
        gl.enableVertexAttribArray(vertexNormalAttribute);

        // Get the uniform locations
        pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
        mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
        nUniform = gl.getUniformLocation(shaderProgram, "uNormalMatrix");

        // Setup texture sampler uniform
        var textureSamplerUniform = gl.getUniformLocation(shaderProgram, "uSampler")
        gl.activeTexture(gl.TEXTURE0);
        gl.uniform1i(textureSamplerUniform, 0);
        gl.bindTexture(gl.TEXTURE_2D, 0);
    }

    function getShader(gl, str, type) {
        var shader = gl.createShader(type);
        gl.shaderSource(shader, str);
        gl.compileShader(shader);

        if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
            console.log("JS:Shader compile failed");
            console.log(gl.getShaderInfoLog(shader));
            return null;
        }

        return shader;
    }