interaction.js Example File

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  ** This file is part of the QtCanvas3D module of the Qt Toolkit.
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  Qt.include("gl-matrix.js")
  Qt.include("ThreeJSLoader.js")

  var gl;

  var texturedShaderProgram = 0;
  var vertexShader = 0;
  var fragmentShader = 0;

  var vertexPositionAttribute;
  var textureCoordAttribute;
  var vertexNormalAttribute;

  var pMatrixUniform;
  var mvMatrixUniform;
  var nMatrixUniform;
  var textureSamplerUniform;

  var barrelTexture = 0;

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

  var canvas3d;
  var isLogEnabled = false;

  function log(message) {
      if (isLogEnabled)
          console.log(message)
  }

  function Model() {
      this.verticesVBO = 0;
      this.normalsVBO  = 0;
      this.texCoordVBO = 0;
      this.indexVBO    = 0;
      this.count       = 0;
  }

  var theModel = new Model();

  function initializeGL(canvas) {
      canvas3d = canvas
      log("*******************************************************************************************")
      log("initializeGL ENTER...")
      try {
          startTime = Date.now();

          // Get the OpenGL context jsonObj that represents the API we call
          log("Getting Context");
          gl = canvas.getContext("canvas3d", {depth:true, antialias:true, alpha:false});
          log("Context received "+gl);

          var contextConfig = gl.getContextAttributes();
          log("Depth: "+contextConfig.alpha);
          log("Stencil: "+contextConfig.stencil);
          log("Antialiasing: "+contextConfig.antialias);
          log("Premultiplied alpha: "+contextConfig.premultipliedAlpha);
          log("Preserve drawingbuffer: "+contextConfig.preserveDrawingBuffer);
          log("Prefer Low Power To High Performance: "+contextConfig.preferLowPowerToHighPerformance);
          log("Fail If Major Performance Caveat: "+contextConfig.failIfMajorPerformanceCaveat);

          // Setup the OpenGL state
          gl.enable(gl.DEPTH_TEST);
          gl.enable(gl.CULL_FACE);

          gl.frontFace(gl.CCW);
          gl.cullFace(gl.BACK);

          gl.disable(gl.BLEND);

          gl.clearColor(0.98, 0.98, 0.98, 1.0);
          gl.clearDepth(1.0);

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

          // Initialize the shader program
          initShaders();

          // Initialize buffers
          theModel.verticesVBO = gl.createBuffer();
          theModel.verticesVBO.name = "BarrelModel.verticesVBO";
          theModel.normalsVBO = gl.createBuffer();
          theModel.normalsVBO.name = "BarrelModel.normalsVBO";
          theModel.texCoordVBO = gl.createBuffer();
          theModel.texCoordVBO.name = "BarrelModel.texCoordVBO";
          theModel.indexVBO = gl.createBuffer();
          theModel.indexVBO.name = "BarrelModel.indexVBO";

          // Load the barrel texture
          gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
          // Load the Qt logo as texture
          var barrelImage = TextureImageFactory.newTexImage();
          barrelImage.imageLoaded.connect(function() {
              barrelTexture = gl.createTexture();
              barrelTexture.name = "barrelTexture"
              gl.bindTexture(gl.TEXTURE_2D, barrelTexture);
              gl.texImage2D(gl.TEXTURE_2D,    // target
                            0,                // level
                            gl.RGBA,          // internalformat
                            gl.RGBA,          // format
                            gl.UNSIGNED_BYTE, // type
                            barrelImage);     // pixels

              gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
              gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
              gl.generateMipmap(gl.TEXTURE_2D);
          });
          barrelImage.imageLoadingFailed.connect(function() {
              console.log("Texture load FAILED, "+barrelImage.errorString);
          });
          // Aliasing doesn't work correctly with QtQuick compiler for some reason,
          // so use full names for barrel.jpg and barrel.json
          barrelImage.src = "qrc:/qml/interaction/barrel.jpg";

          // Load the model
          log("    Create XMLHttpRequest")
          var request = new XMLHttpRequest();
          log("    XMLHttpRequest.open")
          request.open("GET", "qrc:/qml/interaction/barrel.json");
          log("    XMLHttpRequest.onreadystatechange")
          request.onreadystatechange = function () {
              if (request.readyState === XMLHttpRequest.DONE) {
                  handleLoadedModel(JSON.parse(request.responseText));
              }
          }
          log("    XMLHttpRequest.send")
          request.send();

          log("...initializeGL EXIT");
      } catch(e) {
          console.log("...initializeGL FAILURE!");
          console.log(""+e);
          console.log(""+e.message);
      }
      log("*******************************************************************************************");
  }

  function resizeGL(canvas)
  {
      var pixelRatio = canvas.devicePixelRatio;
      canvas.pixelSize = Qt.size(canvas.width * pixelRatio,
                                 canvas.height * pixelRatio);
      if (gl)
          gl.viewport(0, 0,
                      canvas.width * canvas.devicePixelRatio,
                      canvas.height * canvas.devicePixelRatio);
  }

  function paintGL(canvas) {
      // draw
      gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

      // draw only when we have the mesh and texture
      if (theModel.count <= 0 || barrelTexture == 0) return;

      gl.useProgram(texturedShaderProgram);

      // Calculate the perspective projection
      mat4.perspective(pMatrix, degToRad(45), canvas.width / canvas.height, 0.1, 10000.0);
      gl.uniformMatrix4fv(pMatrixUniform, false, pMatrix);

      // Bind the correct buffers
      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.verticesVBO);
      gl.enableVertexAttribArray(vertexPositionAttribute);
      gl.vertexAttribPointer(vertexPositionAttribute, 3, gl.FLOAT, false, 0, 0);

      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.normalsVBO);
      gl.enableVertexAttribArray(vertexNormalAttribute);
      gl.vertexAttribPointer(vertexNormalAttribute, 3, gl.FLOAT, false, 0, 0);

      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.texCoordVBO);
      gl.enableVertexAttribArray(textureCoordAttribute);
      gl.vertexAttribPointer(textureCoordAttribute, 2, gl.FLOAT, false, 0, 0);

      gl.activeTexture(gl.TEXTURE0);
      gl.bindTexture(gl.TEXTURE_2D, barrelTexture);
      gl.uniform1i(textureSamplerUniform, 0);

      // Calculate and apply the modelview matrix
      mvMatrix = mat4.identity(mvMatrix);
      mvMatrix = mat4.translate(mvMatrix, mvMatrix, [0, -40, -700]);
      mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.xRotSlider), [1, 0, 0]);
      mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.yRotSlider), [0, 1, 0]);
      mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.zRotSlider), [0, 0, 1]);
      gl.uniformMatrix4fv(mvMatrixUniform, false, mvMatrix);

      // Calculate normal matrix
      nMatrix = mat4.invert(nMatrix, mvMatrix);
      nMatrix = mat4.transpose(nMatrix, nMatrix);
      gl.uniformMatrix4fv(nMatrixUniform, false, nMatrix);

      // Draw the barrel
      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, theModel.indexVBO);
      gl.drawElements(gl.TRIANGLES, theModel.count, gl.UNSIGNED_SHORT, 0);

      // Calculate and apply the modelview matrix
      mvMatrix = mat4.identity(mvMatrix);
      mvMatrix = mat4.translate(mvMatrix, mvMatrix, [-250, -50, -700]);
      mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.xRotSlider), [0, 1, 0]);
      gl.uniformMatrix4fv(mvMatrixUniform, false, mvMatrix);

      // Calculate normal matrix
      nMatrix = mat4.invert(nMatrix, mvMatrix);
      nMatrix = mat4.transpose(nMatrix, nMatrix);
      gl.uniformMatrix4fv(nMatrixUniform, false, nMatrix);

      // Draw the barrel
      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, theModel.indexVBO);
      gl.drawElements(gl.POINTS, theModel.count, gl.UNSIGNED_SHORT, 0);

      // Calculate and apply the modelview matrix
      mvMatrix = mat4.identity(mvMatrix);
      mvMatrix = mat4.translate(mvMatrix, mvMatrix, [250, -50, -700]);
      mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.zRotSlider), [0, 1, 0]);
      gl.uniformMatrix4fv(mvMatrixUniform, false, mvMatrix);

      // Calculate normal matrix
      nMatrix = mat4.invert(nMatrix, mvMatrix);
      nMatrix = mat4.transpose(nMatrix, nMatrix);
      gl.uniformMatrix4fv(nMatrixUniform, false, nMatrix);

      // Draw the barrel
      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, theModel.indexVBO);
      gl.drawElements(gl.LINES, theModel.count, gl.UNSIGNED_SHORT, 0);
  }

  function handleLoadedModel(jsonObj) {
      log("*******************************************************************************************");
      log("handleLoadedModel ENTER...")
      var modelData = parseJSON3DModel(jsonObj, "");

      log("    "+theModel.verticesVBO);
      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.verticesVBO);
      gl.bufferData(gl.ARRAY_BUFFER,
                    new Float32Array(modelData.vertices),
                    gl.STATIC_DRAW);

      log("    "+theModel.normalsVBO);
      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.normalsVBO);
      gl.bufferData(gl.ARRAY_BUFFER,
                    new Float32Array(modelData.normals),
                    gl.STATIC_DRAW);

      log("    "+theModel.texCoordVBO);
      gl.bindBuffer(gl.ARRAY_BUFFER, theModel.texCoordVBO);
      gl.bufferData(gl.ARRAY_BUFFER,
                    new Float32Array(modelData.texCoords[0]),
                    gl.STATIC_DRAW);

      log("    "+theModel.indexVBO);
      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, theModel.indexVBO);
      gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
                    new Uint16Array(modelData.indices),
                    gl.STATIC_DRAW);

      theModel.count = modelData.indices.length;
      log("...handleLoadedModel EXIT");
      log("*******************************************************************************************");
  }

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

  function initShaders()
  {
      log("    initShaders ENTER...")

      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 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_PointSize = 1.0; \
                               }", gl.VERTEX_SHADER);

      fragmentShader = getShader(gl,
                                 "varying highp vec2 vTextureCoord;             \
                                  varying highp vec3 vLighting;                 \
                                                                                \
                                  uniform sampler2D uSampler;                   \
                                                                                \
                                  void main(void) {                             \
                                      mediump vec4 texelColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));  \
                                      gl_FragColor = vec4(texelColor.rgb * vLighting, 1.0);                                   \
                                  }", gl.FRAGMENT_SHADER);

      texturedShaderProgram = gl.createProgram();
      texturedShaderProgram.name = "TexturedShaderProgram";
      gl.attachShader(texturedShaderProgram, vertexShader);
      gl.attachShader(texturedShaderProgram, fragmentShader);
      gl.linkProgram(texturedShaderProgram);

      if (!gl.getProgramParameter(texturedShaderProgram, gl.LINK_STATUS)) {
          console.log("Could not initialize shaders");
          console.log(gl.getProgramInfoLog(texturedShaderProgram));
      }

      gl.useProgram(texturedShaderProgram);

      // look up where the vertex data needs to go.
      vertexPositionAttribute = gl.getAttribLocation(texturedShaderProgram, "aVertexPosition");
      vertexPositionAttribute.name = "aVertexPosition_AttribLocation";
      gl.enableVertexAttribArray(vertexPositionAttribute);
      vertexNormalAttribute = gl.getAttribLocation(texturedShaderProgram, "aVertexNormal");
      vertexPositionAttribute.name = "aVertexNormal_AttribLocation";
      gl.enableVertexAttribArray(vertexNormalAttribute);
      textureCoordAttribute = gl.getAttribLocation(texturedShaderProgram, "aTextureCoord");
      vertexPositionAttribute.name = "aTextureCoord_AttribLocation";
      gl.enableVertexAttribArray(textureCoordAttribute);

      pMatrixUniform  = gl.getUniformLocation(texturedShaderProgram, "uPMatrix");
      pMatrixUniform.name = "uPMatrix_UniformLocation";
      mvMatrixUniform = gl.getUniformLocation(texturedShaderProgram, "uMVMatrix");
      mvMatrixUniform.name = "uMVMatrix_UniformLocation";
      textureSamplerUniform = gl.getUniformLocation(texturedShaderProgram, "uSampler")
      textureSamplerUniform.name = "uSampler_UniformLocation";
      nMatrixUniform = gl.getUniformLocation(texturedShaderProgram, "uNormalMatrix");
      nMatrixUniform.name = "uNormalMatrix_UniformLocation";
      log("    ... initShaders EXIT");
  }

  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;
  }