472 lines
14 KiB
JavaScript
472 lines
14 KiB
JavaScript
/**
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* @file 查找轮廓中的关键点
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* @author mengke01(kekee000@gmail.com)
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*
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* 查找方法为此处文章的方法
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* http://wenku.baidu.com/link?url=Sz1BbYjfA7IeHAMVJ1TPlXiMhACc6sWhHliPJqAUxxtC5K9PYf4j3ile6patUEUMOE_9uJdsS1EGJBFLVbhXcn7Qe8l_FxuT3QVI8nm1aZG
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*
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* 关键点标记定义：
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*
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* p.left 左侧类型
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* p.right: 右侧类型
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* 直线为1，
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* 曲线为2
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*/
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define(
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function (require) {
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var makeLink = require('graphics/pathUtil').makeLink;
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var getCos = require('graphics/vector').getCos;
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var getDist = require('graphics/vector').getDist;
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var THETA_TANGENCY = 0.1; // 相切抑制
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var THETA_CORNER = 0.5; // 拐点抑制
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var THETA_MARK_COUNT = 0.8; // 标记点个数抑制
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var THETA_INFLEXION_RANGE = 0.05; // 切线点之间的距离抑制
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function isSegmentLine(contour, start, end, isLast) {
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var contourSize = contour.length;
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var mid;
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var thetaDistance = 10; // 判断直线点距离
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// 判断中间点距离
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if (isLast) {
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mid = contour[Math.floor(start.index + (contourSize - start.index + end.index) / 2) % contourSize];
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}
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else {
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mid = contour[Math.floor((start.index + end.index) / 2)];
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}
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if (getDist(start, end, mid) > thetaDistance) {
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return false;
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}
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// 随机选取 几个点进行直线判断
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var startIndex = start.index;
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var endIndex = end.index;
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if (isLast) {
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startIndex = start.index;
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endIndex = contourSize + end.index;
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}
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// 距离比较长的话可以适当放大
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if (endIndex - startIndex > 100) {
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thetaDistance = 20;
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}
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var step = Math.floor(Math.max((endIndex - startIndex) / 10, 4));
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var lineFlag = true;
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for (var j = startIndex + step; j < endIndex; j += step) {
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var dist = getDist(start, end, contour[j % contourSize]);
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if (dist > thetaDistance) {
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lineFlag = false;
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break;
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}
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}
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return lineFlag;
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}
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/**
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* 计算当前点的theta值
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*
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* @param {Object} cur 当前点
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* @param {Object} leftR 左侧平均
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* @param {Object} rightR 右侧平均
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* @return {number} theta值
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*/
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function computeTheta(p, leftR, rightR) {
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var leftX = 0;
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var leftY = 0;
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var t = 0;
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var cur = p;
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while (t++ < leftR) {
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cur = cur.prev;
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leftX += cur.x;
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leftY += cur.y;
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}
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leftX = leftX / leftR;
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leftY = leftY / leftR;
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// 右侧分量
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var rightX = 0;
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var rightY = 0;
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t = 0;
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cur = p;
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while (t++ < rightR) {
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cur = cur.next;
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rightX += cur.x;
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rightY += cur.y;
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}
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rightX = rightX / rightR;
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rightY = rightY / rightR;
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leftX = p.x - leftX;
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leftY = p.y - leftY;
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rightX = rightX - p.x;
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rightY = rightY - p.y;
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var theta = Math.acos(getCos(leftX, leftY, rightX, rightY));
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var m = leftX * rightY - rightX * leftY;
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if (m > 0) {
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return theta;
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}
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else if (m < 0) {
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return -theta;
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}
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return 0;
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}
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/**
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* 标记点的左右已经被访问过了
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*
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* @param {Object} p 点
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* @param {number} rl 左半径
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* @param {number} rr 右半径
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*/
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function markVisited(p, rl, rr) {
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var j;
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var left = p;
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var right = p;
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p.visited = true;
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if (!rr || rr === rl) {
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j = 0;
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while (j++ < rl) {
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left = left.prev;
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right = right.next;
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left.visited = right.visited = true;
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}
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}
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else {
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j = 0;
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while (j++ < rl) {
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left = left.prev;
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left.visited = true;
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}
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j = 0;
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while (j++ < rr) {
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right = right.next;
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right.visited = true;
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}
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}
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}
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/**
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* 查找和标记直线点
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*
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* @param {Array} contour 轮廓
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* @param {Array} breakPoints 关键点
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* @param {number} r 查找范围
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* @return {Array} 关键点
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*/
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function findLinePoints(contour, breakPoints, r) {
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// 根据角点查找竖直和水平线
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var linePoints = [];
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var contourSize = contour.length;
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for (var i = 0, l = breakPoints.length; i < l; i++) {
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var isLast = i === l - 1;
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var p = breakPoints[i];
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var next = isLast ? breakPoints[0] : breakPoints[i + 1];
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if (p.right === 1) {
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continue;
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}
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var range = isLast ? contourSize - p.index + next.index : next.index - p.index;
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if (range < r) {
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p.right = 1;
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next.left = 1;
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}
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else if (isSegmentLine(contour, p, next, isLast)){
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p.right = 1;
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next.left = 1;
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}
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}
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return breakPoints;
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}
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/**
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* 查找竖直和水平直线点
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*
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* @param {Array} contour 轮廓
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* @param {Array} breakPoints 关键点
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* @param {number} r 查找范围
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* @return {Array} 关键点
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*/
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function findVerticalAndHorizontalPoints(contour, breakPoints, r) {
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var contourSize = contour.length;
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for (var i = 0, l = contourSize; i < l; i++) {
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var p = contour[i];
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var cur;
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var count;
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// 查找竖直直线点
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if (p.x === p.next.x && p.x === p.next.next.x) {
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cur = p.next.next;
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count = 2;
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while (cur.x === cur.next.x) {
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cur = cur.next;
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count++;
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}
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if (count > 40) {
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cur = cur.prev;
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//p.right = 1;
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if (-1 == breakPoints.indexOf(p)) {
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breakPoints.push(p);
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}
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markVisited(p, r, count + r);
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// 判断是否角点
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p.theta = computeTheta(p, r, 1);
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p.absTheta = Math.abs(p.theta);
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if (p.absTheta > THETA_CORNER) {
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p.breakPoint = true;
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}
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else if (p.absTheta <= THETA_TANGENCY) {
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p.tangency = true;
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}
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if (count > 80) {
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//cur.left = 1;
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if (-1 == breakPoints.indexOf(cur)) {
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breakPoints.push(cur);
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}
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cur.theta = computeTheta(cur, 1, r);
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cur.absTheta = Math.abs(cur.theta);
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if (cur.absTheta > THETA_CORNER) {
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cur.breakPoint = true;
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}
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else if (cur.absTheta < THETA_TANGENCY) {
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cur.tangency = true;
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}
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}
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i += count;
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}
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}
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else if (p.y === p.next.y && p.y === p.next.next.y) {
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cur = p.next.next;
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count = 2;
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while (cur.y === cur.next.y) {
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cur = cur.next;
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count++;
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}
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if (count > 40) {
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cur = cur.prev;
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//p.right = 1;
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if (-1 == breakPoints.indexOf(p)) {
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breakPoints.push(p);
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}
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//cur.left = 1;
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if (-1 == breakPoints.indexOf(cur)) {
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breakPoints.push(cur);
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}
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markVisited(p, r, count + r);
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// 判断是否角点
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p.theta = computeTheta(p, r, 1);
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p.absTheta = Math.abs(p.theta);
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if (p.absTheta > THETA_CORNER) {
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p.breakPoint = true;
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}
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else if (p.absTheta > THETA_TANGENCY) {
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p.tangency = true;
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}
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cur.theta = computeTheta(cur, 1, r);
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cur.absTheta = Math.abs(cur.theta);
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if (cur.absTheta > THETA_CORNER) {
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cur.breakPoint = true;
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}
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else if (cur.absTheta < THETA_TANGENCY) {
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cur.tangency = true;
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}
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i += count;
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}
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}
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}
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breakPoints.sort(function (a, b) {
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return a.index - b.index;
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});
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return breakPoints;
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}
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/**
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* 查找和标记拐点
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*
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* @param {Array} contour 轮廓
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* @param {Array} breakPoints 关键点
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* @param {number} r 查找范围
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* @return {Array} 关键点
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*/
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function findBreakPoints(contour, breakPoints, r) {
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var j;
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var left;
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var right;
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var max;
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contour.forEach(function (p) {
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if (p.mark && !p.visited) {
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j = 0;
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left = p;
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right = p;
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max = p.absTheta;
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while (j++ < r) {
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left = left.prev;
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right = right.next;
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if (left.absTheta > max) {
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max = left.absTheta;
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}
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if (right.absTheta > max) {
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max = right.absTheta;
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}
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}
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if (max === p.absTheta) {
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p.breakPoint = true;
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breakPoints.push(p);
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markVisited(p, r);
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}
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}
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});
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return breakPoints;
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}
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function fixStartPoint(contour) {
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var i;
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var l;
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var minY = contour[0].y;
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var firstLine = [0];
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for (i = 1, l = contour.length; i < l; i++) {
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if (contour[i].y < minY) {
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minY = contour[i].y;
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firstLine = [i];
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}
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else if (contour[i].y === minY) {
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firstLine.push(i);
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}
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}
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var index = firstLine[0];
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var minX = contour[index].x;
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for (i = 1, l = firstLine.length; i < l; i++) {
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if (contour[firstLine[i]].x < minX) {
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minX = contour[firstLine[i]].x;
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index = firstLine[i];
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}
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}
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if (index !== 0) {
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return contour.slice(index).concat(contour.slice(0, index));
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}
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return contour;
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}
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/**
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* 查找轮廓中的关键点
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*
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* @param {Array} contour 轮廓点集合
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* @return {Array} 轮廓点集合
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*/
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function getBreakPoints(contour) {
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//contour = fixStartPoint(contour);
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contour = makeLink(contour);
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var r = contour.length > 16 ? 10 : 4;
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var contourSize = contour.length;
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var breakPoints = [];
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if (contour.length > 60) {
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breakPoints = findVerticalAndHorizontalPoints(contour, breakPoints, r);
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}
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for (var i = 0, l = contourSize; i < l; i++) {
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p = contour[i];
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if (!p.visited) {
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p.theta = computeTheta(p, r, r);
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p.absTheta = Math.abs(p.theta);
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if (p.absTheta > THETA_CORNER) {
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p.mark = true;
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}
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else if (p.absTheta > THETA_TANGENCY) {
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p.markTangency = true;
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}
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}
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}
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// 非极大抑制查找角点
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breakPoints = findBreakPoints(contour, breakPoints, r);
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// 没有找到拐点，说明拐点不明显，或者为连续曲线，这里采用4等分
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if (breakPoints.length < 2) {
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if (contourSize < 100) {
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var step = Math.floor(contourSize / 2) + 1;
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}
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else {
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var step = Math.floor(contourSize / 4) + 1;
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}
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var startIndex = breakPoints[0] ? breakPoints[0].index : 0;
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for (var i = 0; i < contourSize; i += step) {
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breakPoints.push(contour[(startIndex + i) % contourSize]);
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}
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}
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breakPoints.sort(function (a, b) {
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return a.index - b.index;
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});
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return breakPoints;
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}
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return getBreakPoints;
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}
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);
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