C++与GLUT绘图
本文介绍了一个基于C++和GLUT库的绘图程序，支持绘制点、直线、多边形和圆形。程序提供了丰富的键盘指令进行交互，包括颜色设置、清除屏幕等功能。
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: 20
struct 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 dot
glColor3f(r, g, b);
// invert height because the opengl origin is at top-left instead of bottom-left
glVertex2i(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 color
glClear(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 window
glFlush();
}
// Main
int main(int argc, char** argv) {
int winSizeX, winSizeY;
//set the window size
if (argc == 3) {
winSizeX = atoi(argv[1]);
winSizeY = atoi(argv[2]);
}
else { // default window size
winSizeX = 800;
winSizeY = 600;
}
width = winSizeX;
height = winSizeY;
init();
// initialize OpenGL utility toolkit (glut)
glutInit(&argc, argv);
// single disply and RGB color mapping
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); // set display mode
glutInitWindowSize(winSizeX, winSizeY); // set window size
glutInitWindowPosition(500, 100); // set window position on screen
glutCreateWindow("Lab1 Window"); // set window title
// set up the mouse and keyboard callback functions
glutKeyboardFunc(myKeyboard); // register the keyboard action function
// displayFunc is called whenever there is a need to redisplay the window
glutDisplayFunc(displayFunc); // register the redraw function
// set background color
glClearColor(default_r, default_g, default_b, alpha); // set the background to white
glClear(GL_COLOR_BUFFER_BIT); // clear the buffer
// misc setup
glMatrixMode(GL_PROJECTION); // setup coordinate system
glLoadIdentity();
gluOrtho2D(0, winSizeX, 0, winSizeY);
glShadeModel(GL_FLAT);
glFlush();
glutMainLoop();
return 0;
}
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