计算机图形学实验二

实验报告课程名称：计算机图形学实验项目：区域填充算法实验仪器：计算机系别：计算机学院专业：计算机科学与技术班级姓名：计科1602/学号：2016011日期：2018-12-8成绩：指导教师：一.实验目的(Objects)1.实现多边形的扫描线填充算法。

二.实验内容 (Contents)实现多边形的扫描线填充算法，通过鼠标，交互的画出一个多边形，然后利用种子填充算法，填充指定的区域。

不能使用任何自带的填充区域函数，只能使用画点、画线函数或是直接对图像的某个像素进行赋值操作；三.实验内容 (Your steps or codes, Results) //widget.cpp//2016CYY Cprogramming#include"widget.h"#include<QDebug>#include<QVector>#include<iostream>using namespace std;#define H 1080#define W 1920int click = 0; //端点数量QPoint temp;QPoint first;int result = 1; //判断有没有结束int sign = 1; //2为画线int length = 5;struct edge{int ymax;float x;float dx;edge *next;};edge edge_;QVector<edge> edges[H];QVector<QPoint> points;//填充用bool fin = false;QPoint *Queue = (QPoint *)malloc(length * sizeof(QPoint)); //存放端点的数组Widget::Widget(QWidget *parent) : QWidget(parent){}Widget::~Widget(){}void Widget::mouseMoveEvent(QMouseEvent *event){setMouseTracking(true);if (click > 0 && result != 0){startPt = temp;endPt =event->pos();sign = 2;update();}}void Widget::mouseReleaseEvent(QMouseEvent *event){if (event->button() == Qt::LeftButton){}else if (event->button() == Qt::RightButton){sign = 2;void pscan_push(){for (int k = 1; k < H; k++){for (int i = 0; i < click - 1; i++){if ((Queue[i].y() <= k && k < Queue[i + 1].y() && i != click) || (Queue[i].y() > k && k >= Queue[i + 1].y() && i != click)){if (Queue[i].y() >= Queue[i + 1].y()){edge_.ymax = Queue[i].y();}else{edge_.ymax = Queue[i + 1].y();}if ((Queue[i + 1].y() - Queue[i].y()) != 0){edge_.dx = (float(Queue[i + 1].x()) - float(Queue[i].x())) / (float(Queue[i + 1].y()) - float(Queue[i].y()));}edge_.x = Queue[i].x() + (k - Queue[i].y()) * edge_.dx;edges[k].push_back(edge_);}}}for (int i = 0; i < H; i++){for (int j = 0; j < edges[i].size() - 1; j++){for (int k = 0; k < edges[i].size() - 1 - j; k++){if (edges[i][k].x > edges[i][k + 1].x){swap(edges[i][k].x, edges[i][k + 1].x);}}}}for (int i = 1; i < H; i++){QPoint startPt;QPoint endPt;if (edges[i].size() != 0){for (int j = 0; j < edges[i].size(); j = j + 2){startPt.setY(i);startPt.setX(edges[i][j].x);endPt.setY(i);endPt.setX(edges[i][j + 1].x + 1);points.push_back(startPt);points.push_back(endPt);}}}fin = true;void Widget::mousePressEvent(QMouseEvent * event){if (event->button() == Qt::RightButton){//result = 1;setMouseTracking(true);if (click == 0 && result != 0){for (int i = 0; i < H; i++){edges[i].clear();}points.clear();startPt =event->pos();temp = startPt;first = startPt;Queue[click] = startPt;click++;}else if (result == 0){fin = false;click = 0;result = 1;//sign = 1;update();}else{startPt = temp;endPt =event->pos();if (click >= length){length += 5;Queue = (QPoint *)realloc(Queue, (length) * sizeof(QPoint));}Queue[click] = endPt;click++;sign = 2;update();temp = endPt;}}else if (event->button() == Qt::LeftButton){if (click > 0){startPt = temp;endPt = first;if (click >= length){length += 5;Queue = (QPoint *)realloc(Queue, (length) * sizeof(QPoint));}Queue[click] = endPt;cout << click <<"\n";click++;sign = 1;result = 0;temp = endPt;if (sign == 1){pscan_push();update();}}}else if (event->button() == Qt::MidButton){}}void qpoint(QImage & image, int x, int y){unsigned char *ptrRow = image.scanLine(y);ptrRow[x * 3 + 0] = 0;//64 201 176ptrRow[x * 3 + 1] = 190;ptrRow[x * 3 + 2] = 0;}void drawLine(QImage & image, QPoint pt1, QPoint pt2){QPainter painter(&image);int flag = -1; //1为扫描x，2为扫描yint x = 0;int y = 0;int p1x = pt1.x();int p1y = pt1.y();int p2x = pt2.x();int p2y = pt2.y();int a, b;int d, d1;a = p2x - p1x;b = p2y - p1y;/*||21 | 22|||b12 | 11________|____________________|_______________________ a|11 | 12|22 | 21||*/if (a >= 0 && b <= 0 && a >= -b || a <= 0 && b >= 0 && -a >= b){printf("11\n");a = p2x - p1x;b = p1y - p2y;d = b - 0.5 * a;d1 = b - a;flag = 11;else if (a > 0 && b > 0 && a >= b || a < 0 && b < 0 && -a > -b){printf("12\n");a = p2x - p1x;b = p2y - p1y;d = b - 0.5 * a;d1 = b - a;flag = 12;}else if (b >= 0 && a >= 0 && a < b || b <= 0 && a <= 0 && -a < -b) {b = p1x - p2x;a = p1y - p2y;d = b - 0.5 * a;d1 = b - a;flag = 21;}else if (b < 0 && a > 0 && a < -b || b > 0 && a < 0 && -a < b){b = p2x - p1x;a = p1y - p2y;d = b - 0.5 * a;d1 = b - a;flag = 22;}if (flag == 11){if (p1x < p2x){for (x = p1x, y = p1y; x < p2x; x++){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d >= 0){d += d1;--y;}else{d += b;}}}else{for (x = p1x, y = p1y; x > p2x; x--){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d <= 0){d += d1;++y;}{d += b;}}}}else if (flag == 12){if (p1x < p2x){for (x = p1x, y = p1y; x < p2x; x++){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d >= 0){d += d1;++y;}else{d += b;}}}else{for (x = p1x, y = p1y; x > p2x; x--){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d <= 0){d += d1;--y;}else{d += b;}}}}else if (flag == 21){if (p1y < p2y){for (x = p1x, y = p1y; y < p2y; y++){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d <= 0)d += d1;++x;}else{d += b;}}}else{for (x = p1x, y = p1y; y > p2y; y--){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d >= 0){d += d1;--x;}else{d += b;}}}}else if (flag == 22){if (p1y < p2y){for (x = p1x, y = p1y; y < p2y; y++){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);if (d <= 0){d += d1;--x;}else{d += b;}}}else{for (x = p1x, y = p1y; y > p2y; y--){if (x < 1 || x > W - 1 || y < 1 || y > H - 1){continue;}qpoint(image, x, y);{d += d1;++x;}else{d += b;}}}}}void Widget::paintEvent(QPaintEvent * event){QPainter painter(this);QImage image = QImage(W, H, QImage::Format_RGB888);image.fill(QColor(3, 3, 3));for (int i = 0; i < click - 1; i++){drawLine(image, Queue[i], Queue[i + 1]);}if (sign == 2){drawLine(image, startPt, endPt);}if (fin == true){for (int i = 0; i < points.size(); i = i + 2){drawLine(image, points[i], points[i + 1]);}}painter.drawImage(0, 0, image);}四.实验总结 (Conclusion)通过实验，我学会了扫描线法填充多边形，扫描线主要的难点我认为是一条扫描线经过的区域，如何判断两个点之间的内容是不是处于图形内部，是否应该填充。