Qt 5.6 | Qt Canvas 3D | Qt Quick Item as Texture Example | quickitemtexture.js Example File

Qt 5.6.2 Reference Documentation

# quickitemtexture.js Example File

quickitemtexture/qml/quickitemtexture/quickitemtexture.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 a Qt Quick item 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;
      var canvasTextureProvider = null;
      var textureSourceItem = null;

      function initializeGL(canvas, textureSource) {
          canvas3d = canvas;
          textureSourceItem = textureSource;

          // 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.clearDepth(1.0);
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, false);

          // Use fully transparent clear color to allow other QML components to be seen through
          // Canvas3D where not obscured by the rotating cube.
          gl.clearColor(0.0, 0.0, 0.0, 0.0);

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

          // Initialize the shader program
          initShaders();

          // Initialize vertex and color buffers
          initBuffers();

          // Create a texture from the Qt Quick item
          canvasTextureProvider = gl.getExtension("QTCANVAS3D_texture_provider");
          cubeTexture = canvasTextureProvider.createTextureFromSource(textureSourceItem);

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

      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,
                                              -7.0]);
          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 Program3D 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 initialize 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;
      }