C++实现glut绘制点、直线、多边形、圆

必备环境

• glut.h 头文件
• glut32.lib 对象文件库
• glut32.dll 动态连接库

程序说明

C++实现了用glut画点、画直线、画多边形和画圆形，并有一些清屏、重绘、清楚数据和窗口重绘的功能。

操作说明

• D：进入画点模式
• L：进入画直线模式
  • 第一次单击确定直线起点
  • 第二次单击绘出直线
• P：进入画多边形模式
  • 第一次单击确定多边形起点
  • 第n次单击绘出多边形的线
  • 右击结束该多边形的绘制
• O：进入画圆模式
  • 第一次单击决定圆心位置
  • 第二次单击绘出圆
• C：清除屏幕
• X：消除全部数据
• R：重绘对象
• ` ：数字键调整画笔颜色
  • 1~7对应红橙黄绿蓝靛紫
  • 8为默认黑色
• Q：退出程序

函数说明

void init( )
程序执行初用于告诉用户的基本操作

void displayFunc( void )
glut窗口显示和恢复显示的时候调用的函数

void myKeyboard( unsigned char k, int x, int y )
键盘控制函数，用于绑定不同的画图函数到glut鼠标操作函数、改变画笔颜色及其他一些功能

void drawDot( int x, in y )
在glut坐标轴(x, y)的位置根据画笔设定绘制一个点

void Mouse_Dot( int button, int state, int x, int y )
鼠标控制画点函数

void Mymouse_Line( int button, int state, int x, int y )
鼠标控制画直线函数

void Mymouse_Polygon( int button, int state, int x, int y )
鼠标控制画多边形函数

void Mymouse_Circle( int button, int state, int x, int y )
鼠标控制画圆函数

void drawLine1( int x0, int x1, int y0, int y1, bool xy_interchange )
直线绘制函数，负责区域1和区域5

void drawLine2( int x0, int x1, int y0, int y1, bool xy_interchange )
直线绘制函数，负责区域2和区域6

void drawLine3( int x0, int x1, int y0, int y1, bool xy_interchange )
直线绘制函数，负责区域3和区域7

void drawLine4( int x0, int x1, int y0, int y1, bool xy_interchange )
直线绘制函数，负责区域4和区域8

void DrawLine( int x0, int x1, int y0, int y1 )
直线绘制函数，自行添加，可全区域使用，目前暂给画多边形使用

void drawCircle( int radius, int center_x, int center_y )
圆绘制函数，负责画出一个圆

void CirclePoints( int x, int y, int center_x, int center_y )
圆的八个点的绘制函数，每次画出八个点

void redraw( )
重绘函数，把存储的数据重绘出来

void clear( )
清空当前glut窗口的显示

void erase( )
删除所有保存的数据

重要函数说明

画直线函数，把二维坐标区域分成8个区域，从第四象限靠近y轴的负半轴的区域开始算起为1号区域，逆时针计算。

注意的是，1号区域和5号区域是用同样的函数控制的，唯一不同的是xy_interchange的值。1号区域的画线方向是从原点画到数字1的区域，5号区域的画线是从数字5画到原点。实质上画线的方向是一致的。因此5~8号区域可以按照1~4号区域的相反来运算。

画线的方法是中点二分法。取两个像素点的中点，计算判断邻域像素点取哪一个。

// Draw line for dx>0 and dy>0
void drawLine1(int x0, int x1, int y0, int y1, bool xy_interchange){if (xy_interchange){int change = x0;    x0 = x1;    x1 = change;change = y0;    y0 = y1;    y1 = change;}int x = x1;int y = y1;int a = y1 - y0;int b = -(x1 - x0);int d = -a - 2 * b;int IncE = -2 * b;int IncNE = -2 * a - 2 * b;line_start[num_line] = line_data(x, y);lcp = &line_start[num_line];while (y >= y0){lcp->next = new line_data(x, y);lcp = lcp->next;drawDot(x, y);if (d <= 0){y--;d += IncE;}else{x--;y--;d += IncNE;}}glFlush();return;
}

各方向均ok的画线函数，由于需要每一步都使用乘法和除法，相比上一个画线函数时间复杂一些，但是各方向均可绘图，而且单纯绘制一条直线在人脑反应时间上是无差别的。

void DrawLine(int x0, int x1, int y0, int y1) {//polygon_start[num_polygon] = line_data(x0, y0);int max_dis = abs(x1 - x0);max_dis = max_dis > abs(y0 - y1) ? max_dis : abs(y0 - y1);//lcp = &polygon_start[num_polygon];lcp = temp;if (max_dis != 0) {for (int i = 0; i < max_dis; ++i) {lcp->next = new line_data(x0 + i * (x1 - x0) / max_dis, y0 + i * (y1 - y0) / max_dis);lcp = lcp->next;}}lcp = temp;while (lcp != NULL) {drawDot(lcp->x, lcp->y);temp = lcp;lcp = lcp->next;}glFlush();return;
}

绘制圆形，将一个圆分成1/8个圆，如图所示

可以通过8个点之间相互关系，绘制出整个圆
（x, y） -> （y, x）->（x, -y）->（y, -x）->（-x, -y）->（-y, -x）->（-x, y）->（-y, x）
假设圆的半径为R，只需要计算（0, R）->（R/2, R/2）即可

void CirclePoints(int x, int y, int center_x, int center_y){drawDot(center_x + x, center_y + y);drawDot(center_x + y, center_y + x);drawDot(center_x + x, center_y - y);drawDot(center_x + y, center_y - x);drawDot(center_x - x, center_y - y);drawDot(center_x - y, center_y - x);drawDot(center_x - x, center_y + y);drawDot(center_x - y, center_y + x);glFlush();return;
}

程序添加了颜色管理，清屏等操作。

实现效果

求轻喷~

完整代码

#include <iostream>
#include <stdlib.h>
#include <cmath>
#include "glut.h"
using namespace std;int height, width;
static int xOrg = 0, yOrg = 0;
#define MAX_LINE 100
// Max number of lines for drawing: 100
#define MAX_POLYGON 20
// Max number of polygons for drawing: 20
#define MAX_CIRCLE 20
// Max number of circles for drawing: 20struct line_structure{int x0, x1, y0, y1;
};struct line_data{int x, y;line_data* next;line_data(int _x = -1, int _y = -1){x = _x;y = _y;next = NULL;}
};struct center_data{int c_x, c_y;center_data(int cx = -1, int cy = -1){c_x = cx;c_y = cy;}
};line_structure line[MAX_LINE];
line_data line_start[MAX_LINE];
line_data polygon_start[MAX_POLYGON];
line_data circle_start[MAX_CIRCLE];
center_data center[MAX_CIRCLE];
line_data* lcp;
line_data* temp;int num_line = 0;
int num_polygon = 0;
int num_circle = 0;
int key_line = 1;
bool first_point = true;const float default_r = 255.0;
const float default_g = 255.0;
const float default_b = 255.0;
float r = 0.0;
float g = 0.0;
float b = 0.0;
float alpha = 0.0;void init();
void drawDot(int x, int y);
void Mymouse_Dot(int button, int state, int x, int y);
void Mymouse_Line(int button, int state, int x, int y);
void Mymouse_Polygon(int button, int state, int x, int y);
void Mymouse_Circle(int button, int state, int x, int y);
void drawLine1(int x0, int x1, int y0, int y1, bool xy_interchange);
void drawLine2(int x0, int x1, int y0, int y1, bool xy_interchange);
void drawLine3(int x0, int x1, int y0, int y1, bool xy_interchange);
void drawLine4(int x0, int x1, int y0, int y1, bool xy_interchange);
void DrawLine(int x0, int x1, int y0, int y1);
void drawCircle(int radius, int center_x, int center_y);
void CirclePoints(int x, int y, int center_x, int center_y);
void redraw();
void myKeyboard(unsigned char key, int x, int y);
void clear();
void erase();
void displayFunc(void);void init(){cout << "Welcome GLUT painter" << endl;cout << "Here are command key: (case insensitive)" << endl;cout << "\tD - Dot Mode" << endl;cout << "\tL - Line Mode" << endl;cout << "\tP - Polygon Mode" << endl;cout << "\tO - Circle Mode" << endl;cout << "\tC - Clear Screen" << endl;cout << "\tX - Clear all objects" << endl;cout << "\tR - Redraw Objects" << endl;cout << "\t` - Number to set color" << endl;cout << "\tQ - Quit" << endl;
}// Draw 8 points
void CirclePoints(int x, int y, int center_x, int center_y){drawDot(center_x + x, center_y + y);drawDot(center_x + y, center_y + x);drawDot(center_x + x, center_y - y);drawDot(center_x + y, center_y - x);drawDot(center_x - x, center_y - y);drawDot(center_x - y, center_y - x);drawDot(center_x - x, center_y + y);drawDot(center_x - y, center_y + x);glFlush();return;
}// Draw a circle
void drawCircle(int radius, int center_x, int center_y){int x = 0;int y = radius;int d = 1 - radius;int IncE = 3;int IncSE = -2 * radius + 5;while (x <= y){if (d <= 0){x++;d += IncE;IncE += 2;IncSE += 2;}else{x++;y--;d += IncSE;IncE += 2;IncSE += 4;}lcp->next = new line_data(x, y);lcp = lcp->next;CirclePoints(x, y, center_x, center_y);}return;
}// Mouse control for circle drawing
void Mymouse_Circle(int button, int state, int x, int y){if (state == GLUT_DOWN && first_point == true){cout << "\tcircle center" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;center[num_circle] = center_data(x, y);first_point = false;}else if (state == GLUT_DOWN && first_point == false){cout << "\tmouse clicks" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;int radius = (int)sqrt(pow(x - center[num_circle].c_x, 2) + pow(y - center[num_circle].c_y, 2));circle_start[num_circle] = line_data(center[num_circle].c_x + 0, center[num_circle].c_y + radius);lcp = &circle_start[num_circle];drawCircle(radius, center[num_circle].c_x, center[num_circle].c_y);num_circle++;first_point = true;}return;
}// Clear screen
void clear(){glClearColor(default_r, default_g, default_b, alpha);glClear(GL_COLOR_BUFFER_BIT);glFlush();
}// Clear objects
void erase(){for (int i = 0; i < num_line; i++){if (line_start[i].next != NULL){lcp = line_start[i].next;while (lcp != NULL){temp = lcp;lcp = lcp->next;delete(temp);}}}num_line = 0;for (int i = 0; i < num_polygon; i++){if (polygon_start[i].next != NULL){lcp = polygon_start[i].next;while (lcp != NULL){temp = lcp;lcp = lcp->next;delete(temp);}}}num_polygon = 0;for (int i = 0; i < num_circle; i++){if (circle_start[i].next != NULL){lcp = circle_start[i].next;while (lcp != NULL){temp = lcp;lcp = lcp->next;delete(temp);}}}num_circle = 0;
}// Mouse control for polygon drawing
void Mymouse_Polygon(int button, int state, int x, int y){if (button == GLUT_LEFT_BUTTON){if (state == GLUT_DOWN && first_point == true){cout << "\tpolygon starts" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;polygon_start[num_polygon] = line_data(x, y);temp = lcp = &polygon_start[num_polygon];first_point = false;num_polygon++;}else if (state == GLUT_DOWN && first_point == false){cout << "\tpolygon clicks" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;DrawLine(temp->x, x, temp->y, y);}}else if (button == GLUT_RIGHT_BUTTON){if (state == GLUT_DOWN){first_point = true;}}return;
}void DrawLine(int x0, int x1, int y0, int y1) {//polygon_start[num_polygon] = line_data(x0, y0);int max_dis = abs(x1 - x0);max_dis = max_dis > abs(y0 - y1) ? max_dis : abs(y0 - y1);//lcp = &polygon_start[num_polygon];lcp = temp;if (max_dis != 0) {for (int i = 0; i < max_dis; ++i) {lcp->next = new line_data(x0 + i * (x1 - x0) / max_dis, y0 + i * (y1 - y0) / max_dis);lcp = lcp->next;}}lcp = temp;while (lcp != NULL) {drawDot(lcp->x, lcp->y);temp = lcp;lcp = lcp->next;}glFlush();return;
}// Redraw all objects stored
void redraw(){int i;line_data* rd_line;line_data* rd_polygon;line_data* rd_circle;for (i = 0; i<num_line; i++){rd_line = &line_start[i];while (rd_line != NULL){drawDot(rd_line->x, rd_line->y);rd_line = rd_line->next;}}for (i = 0; i<num_polygon; i++){rd_polygon = &polygon_start[i];while (rd_polygon != NULL){drawDot(rd_polygon->x, rd_polygon->y);rd_polygon = rd_polygon->next;}}for (i = 0; i<num_circle; i++){rd_circle = &circle_start[i];while (rd_circle != NULL){CirclePoints(rd_circle->x, rd_circle->y, center[i].c_x, center[i].c_y);rd_circle = rd_circle->next;}}glFlush();
}// draw a dot at location with integer coordinates (x,y)
void drawDot(int x, int y){glBegin(GL_POINTS);// set the color of dotglColor3f(r, g, b);// invert height because the opengl origin is at top-left instead of bottom-leftglVertex2i(x, height - y);glEnd();
}// Mouse callback function
void Mymouse_Dot(int button, int state, int x, int y){if (state == GLUT_DOWN) {cout << "\tdot clicks" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;drawDot(x, y);glFlush();}
}#pragma region Drawline// Mouse control for line drawing
void Mymouse_Line(int button, int state, int x, int y){if (state == GLUT_DOWN && first_point == true){cout << "\tline starts" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;line[num_line].x0 = x;line[num_line].y0 = y;first_point = false;}else if (state == GLUT_DOWN && first_point == false){cout << "\tline ends" << endl;cout << "\t\ton location (" << x << ", " << y << ")" << endl;line[num_line].x1 = x;line[num_line].y1 = y;first_point = true;int dx = line[num_line].x1 - line[num_line].x0;int dy = line[num_line].y1 - line[num_line].y0;if (dx >= 0 && dy > 0 && abs(dx) < abs(dy)){drawLine1(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, false);}else if (dx > 0 && dy >= 0 && abs(dx) >= abs(dy)){drawLine2(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, false);}else if (dx > 0 && dy <= 0 && abs(dx) > abs(dy)){drawLine3(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, false);}else if (dx >= 0 && dy < 0 && abs(dx) <= abs(dy)){drawLine4(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, false);}else if (dx <= 0 && dy < 0 && abs(dx) < abs(dy)){drawLine1(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, true);}else if (dx < 0 && dy <= 0 && abs(dx) >= abs(dy)){drawLine2(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, true);}else if (dx < 0 && dy >= 0 && abs(dx) > abs(dy)){drawLine3(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, true);}else{drawLine4(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1, true);}//DrawLine(line[num_line].x0, line[num_line].x1, line[num_line].y0, line[num_line].y1);num_line++;}return;
}// Draw line for dx>0 and dy>0
void drawLine1(int x0, int x1, int y0, int y1, bool xy_interchange){if (xy_interchange){int change = x0;    x0 = x1;    x1 = change;change = y0;    y0 = y1;    y1 = change;}int x = x1;int y = y1;int a = y1 - y0;int b = -(x1 - x0);int d = -a - 2 * b;int IncE = -2 * b;int IncNE = -2 * a - 2 * b;line_start[num_line] = line_data(x, y);lcp = &line_start[num_line];while (y >= y0){lcp->next = new line_data(x, y);lcp = lcp->next;drawDot(x, y);if (d <= 0){y--;d += IncE;}else{x--;y--;d += IncNE;}}glFlush();return;
}// Draw line for dx>0 and dy<0
void drawLine2(int x0, int x1, int y0, int y1, bool xy_interchange){if (xy_interchange){int change = x0;    x0 = x1;    x1 = change;change = y0;    y0 = y1;    y1 = change;}int x = x0;int y = y0;int a = y1 - y0;int b = -(x1 - x0);int d = 2 * a + b;int IncE = 2 * a;int IncNE = 2 * a + 2 * b;line_start[num_line] = line_data(x, y);lcp = &line_start[num_line];while (x <= x1){lcp->next = new line_data(x, y);lcp = lcp->next;drawDot(x, y);if (d <= 0){x++;d += IncE;}else{x++;y++;d += IncNE;}}glFlush();return;
}// Draw line for dx<0 and dy>0
void drawLine3(int x0, int x1, int y0, int y1, bool xy_interchange){if (xy_interchange){int change = x0;    x0 = x1;    x1 = change;change = y0;    y0 = y1;    y1 = change;}int x = x0;int y = y0;int a = y0 - y1;int b = -(x1 - x0);int d = 2 * a + b;int IncE = 2 * a;int IncNE = 2 * a + 2 * b;line_start[num_line] = line_data(x, y);lcp = &line_start[num_line];while (x <= x1){lcp->next = new line_data(x, y);lcp = lcp->next;drawDot(x, y);if (d <= 0){x++;d += IncE;}else{x++;y--;d += IncNE;}}glFlush();return;
}// Draw line for dx<0 and dy<0
void drawLine4(int x0, int x1, int y0, int y1, bool xy_interchange){if (xy_interchange){int change = x0;    x0 = x1;    x1 = change;change = y0;    y0 = y1;    y1 = change;}int x = x0;int y = y0;int a = y1 - y0;int b = -(x1 - x0);int d = a - 2 * b;int IncE = -2 * b;int IncNE = 2 * a - 2 * b;line_start[num_line] = line_data(x, y);lcp = &line_start[num_line];while (y >= y1){lcp->next = new line_data(x, y);lcp = lcp->next;drawDot(x, y);if (d <= 0){y--;d += IncE;}else{x++;y--;d += IncNE;}}glFlush();return;
}
#pragma endregion// Keyboard callback function
void myKeyboard(unsigned char key, int x, int y) {switch (key) {// Draw dots with 'd' or 'D'case 'd':case 'D':cout << "\nchoose the Dot mode" << endl;glutMouseFunc(Mymouse_Dot);break;// Draw lines with 'l' or 'L'case 'l':case 'L':cout << "\nchoose the Line mode" << endl;first_point = true;glutMouseFunc(Mymouse_Line);break;// Draw polygons with 'p' or 'P'case 'p':case 'P':cout << "\nchoose the Polygon mode" << endl;first_point = true;glutMouseFunc(Mymouse_Polygon);break;// Draw circle with 'c' or 'C'case 'o':case 'O':cout << "\nchoose the Circle mode" << endl;first_point = true;glutMouseFunc(Mymouse_Circle);break;// Redraw all with 'r' or 'R'case 'r':case 'R':cout << "\nnow redraw all" << endl;redraw();break;// Clear screen with 'c' or 'C'case 'c':case 'C':cout << "\nclear the screen" << endl;clear();break;case 'x':case 'X':cout << "\nclear all the objects" << endl;erase();break;// Quit with 'q' or 'Q'case 'q':case 'Q':cout << "\napplication exit successfully" << endl;exit(0);break;case '1':r = 1.0;    g = 0;      b = 0;break;case '2':r = 1.0;    g = 0.5;    b = 0;break;case '3':r = 1.0;    g = 1.0;    b = 0;break;case '4':r = 0;      g = 1.0;    b = 0;break;case '5':r = 0;      g = 0;      b = 1.0;break;case '6':r = 0;      g = 1.0;    b = 1.0;break;case '7':r = 1.0;    g = 0;      b = 1.0;break;case '8':r = 0;      g = 0;      b = 0;break;default:break;}
}// Display function
void displayFunc(void){// clear the entire window to the background colorglClear(GL_COLOR_BUFFER_BIT);glClearColor(default_r, default_g, default_b, alpha);// draw the contents!!! Iterate your object's data structure!redraw();// flush the queue to actually paint the dots on the opengl windowglFlush();
}// Main
int main(int argc, char** argv) {int winSizeX, winSizeY;//set the window sizeif (argc == 3) {winSizeX = atoi(argv[1]);winSizeY = atoi(argv[2]);}else { // default window sizewinSizeX = 800;winSizeY = 600;}width = winSizeX;height = winSizeY;init();// initialize OpenGL utility toolkit (glut)glutInit(&argc, argv);// single disply and RGB color mappingglutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); // set display modeglutInitWindowSize(winSizeX, winSizeY);      // set window sizeglutInitWindowPosition(500, 100);                // set window position on screenglutCreateWindow("Lab1 Window");             // set window title// set up the mouse and keyboard callback functionsglutKeyboardFunc(myKeyboard);               // register the keyboard action function// displayFunc is called whenever there is a need to redisplay the windowglutDisplayFunc(displayFunc);               // register the redraw function// set background colorglClearColor(default_r, default_g, default_b, alpha);   // set the background to whiteglClear(GL_COLOR_BUFFER_BIT);               // clear the buffer// misc setupglMatrixMode(GL_PROJECTION);                // setup coordinate systemglLoadIdentity();gluOrtho2D(0, winSizeX, 0, winSizeY);glShadeModel(GL_FLAT);glFlush();glutMainLoop();return 0;
}