guoyao-jiankang/public/static/threejs135/js/misc/VolumeSlice.js

( function () {

	/**
 * This class has been made to hold a slice of a volume data
 * @class
 * @param   {Volume} volume    The associated volume
 * @param   {number}       [index=0] The index of the slice
 * @param   {string}       [axis='z']      For now only 'x', 'y' or 'z' but later it will change to a normal vector
 * @see Volume
 */

	function VolumeSlice( volume, index, axis ) {

		var slice = this;
		/**
   * @member {Volume} volume The associated volume
   */

		this.volume = volume;
		/**
   * @member {Number} index The index of the slice, if changed, will automatically call updateGeometry at the next repaint
   */

		index = index || 0;
		Object.defineProperty( this, 'index', {
			get: function () {

				return index;

			},
			set: function ( value ) {

				index = value;
				slice.geometryNeedsUpdate = true;
				return index;

			}
		} );
		/**
   * @member {String} axis The normal axis
   */

		this.axis = axis || 'z';
		/**
   * @member {HTMLCanvasElement} canvas The final canvas used for the texture
   */

		/**
   * @member {CanvasRenderingContext2D} ctx Context of the canvas
   */

		this.canvas = document.createElement( 'canvas' );
		/**
   * @member {HTMLCanvasElement} canvasBuffer The intermediary canvas used to paint the data
   */

		/**
   * @member {CanvasRenderingContext2D} ctxBuffer Context of the canvas buffer
   */

		this.canvasBuffer = document.createElement( 'canvas' );
		this.updateGeometry();
		var canvasMap = new THREE.Texture( this.canvas );
		canvasMap.minFilter = THREE.LinearFilter;
		canvasMap.wrapS = canvasMap.wrapT = THREE.ClampToEdgeWrapping;
		var material = new THREE.MeshBasicMaterial( {
			map: canvasMap,
			side: THREE.DoubleSide,
			transparent: true
		} );
		/**
   * @member {Mesh} mesh The mesh ready to get used in the scene
   */

		this.mesh = new THREE.Mesh( this.geometry, material );
		this.mesh.matrixAutoUpdate = false;
		/**
   * @member {Boolean} geometryNeedsUpdate If set to true, updateGeometry will be triggered at the next repaint
   */

		this.geometryNeedsUpdate = true;
		this.repaint();
		/**
   * @member {Number} iLength Width of slice in the original coordinate system, corresponds to the width of the buffer canvas
   */

		/**
   * @member {Number} jLength Height of slice in the original coordinate system, corresponds to the height of the buffer canvas
   */

		/**
   * @member {Function} sliceAccess Function that allow the slice to access right data
   * @see Volume.extractPerpendicularPlane
   * @param {Number} i The first coordinate
   * @param {Number} j The second coordinate
   * @returns {Number} the index corresponding to the voxel in volume.data of the given position in the slice
   */

	}

	VolumeSlice.prototype = {
		constructor: VolumeSlice,

		/**
   * @member {Function} repaint Refresh the texture and the geometry if geometryNeedsUpdate is set to true
   * @memberof VolumeSlice
   */
		repaint: function () {

			if ( this.geometryNeedsUpdate ) {

				this.updateGeometry();

			}

			var iLength = this.iLength,
				jLength = this.jLength,
				sliceAccess = this.sliceAccess,
				volume = this.volume,
				canvas = this.canvasBuffer,
				ctx = this.ctxBuffer; // get the imageData and pixel array from the canvas

			var imgData = ctx.getImageData( 0, 0, iLength, jLength );
			var data = imgData.data;
			var volumeData = volume.data;
			var upperThreshold = volume.upperThreshold;
			var lowerThreshold = volume.lowerThreshold;
			var windowLow = volume.windowLow;
			var windowHigh = volume.windowHigh; // manipulate some pixel elements

			var pixelCount = 0;

			if ( volume.dataType === 'label' ) {

				//this part is currently useless but will be used when colortables will be handled
				for ( var j = 0; j < jLength; j ++ ) {

					for ( var i = 0; i < iLength; i ++ ) {

						var label = volumeData[ sliceAccess( i, j ) ];
						label = label >= this.colorMap.length ? label % this.colorMap.length + 1 : label;
						var color = this.colorMap[ label ];
						data[ 4 * pixelCount ] = color >> 24 & 0xff;
						data[ 4 * pixelCount + 1 ] = color >> 16 & 0xff;
						data[ 4 * pixelCount + 2 ] = color >> 8 & 0xff;
						data[ 4 * pixelCount + 3 ] = color & 0xff;
						pixelCount ++;

					}

				}

			} else {

				for ( var j = 0; j < jLength; j ++ ) {

					for ( var i = 0; i < iLength; i ++ ) {

						var value = volumeData[ sliceAccess( i, j ) ];
						var alpha = 0xff; //apply threshold

						alpha = upperThreshold >= value ? lowerThreshold <= value ? alpha : 0 : 0; //apply window level

						value = Math.floor( 255 * ( value - windowLow ) / ( windowHigh - windowLow ) );
						value = value > 255 ? 255 : value < 0 ? 0 : value | 0;
						data[ 4 * pixelCount ] = value;
						data[ 4 * pixelCount + 1 ] = value;
						data[ 4 * pixelCount + 2 ] = value;
						data[ 4 * pixelCount + 3 ] = alpha;
						pixelCount ++;

					}

				}

			}

			ctx.putImageData( imgData, 0, 0 );
			this.ctx.drawImage( canvas, 0, 0, iLength, jLength, 0, 0, this.canvas.width, this.canvas.height );
			this.mesh.material.map.needsUpdate = true;

		},

		/**
   * @member {Function} Refresh the geometry according to axis and index
   * @see Volume.extractPerpendicularPlane
   * @memberof VolumeSlice
   */
		updateGeometry: function () {

			var extracted = this.volume.extractPerpendicularPlane( this.axis, this.index );
			this.sliceAccess = extracted.sliceAccess;
			this.jLength = extracted.jLength;
			this.iLength = extracted.iLength;
			this.matrix = extracted.matrix;
			this.canvas.width = extracted.planeWidth;
			this.canvas.height = extracted.planeHeight;
			this.canvasBuffer.width = this.iLength;
			this.canvasBuffer.height = this.jLength;
			this.ctx = this.canvas.getContext( '2d' );
			this.ctxBuffer = this.canvasBuffer.getContext( '2d' );
			if ( this.geometry ) this.geometry.dispose(); // dispose existing geometry

			this.geometry = new THREE.PlaneGeometry( extracted.planeWidth, extracted.planeHeight );

			if ( this.mesh ) {

				this.mesh.geometry = this.geometry; //reset mesh matrix

				this.mesh.matrix.identity();
				this.mesh.applyMatrix4( this.matrix );

			}

			this.geometryNeedsUpdate = false;

		}
	};

	THREE.VolumeSlice = VolumeSlice;

} )();