OpenGL实验二利用鼠标、键盘，菜单等方式对图元进行交互操作

实验目的：

利用鼠标、键盘，菜单等方式对图元进行交互操作

实验内容：

1、用鼠标拖动画直线，线段终点始终跟随鼠标移动；

2、使用菜单界面修改直线的颜色；

3、利用键盘控制直线在屏幕上移动；

可以改进的设想：

1.做一个画图程序可以在鼠标移动函数里修改，每次画点，并定义全局数组保存点的坐标；

2.修改颜色时可以弹出一个颜色表，可以用子窗口实现，并且定义模式为拾取模式

3.可以画多根线，然后按下右键，拖动鼠标画一个矩形，在矩形区域内的线段会变色

4.点击某个线，然后拖动线段

5.Ctrl + 滚轮放大缩小线段

5. 同时按下上方向键和左方向键，然后线段想左上方移动（没思路）

源代码：

IDE：codeblocks
1、用鼠标拖动画直线，线段终点始终跟随鼠标移动；
2、使用菜单界面修改直线的颜色；
3、利用键盘控制直线在屏幕上移动；
*/
#include <windows.h>
#include <GL/glut.h>
#include <iostream>
#include <stdio.h>
using namespace std;

double WINHEIGHT = 0,WINWIDTH = 0;
bool FirstPointHadDraw = false, LineHadDraw = false;
int x0 = 0, y0 = 0, xEnd = 0, yEnd = 0;
double moveSpeed = 3;

void init();
void MyIdle();
void MyReshape(int w, int h);

void display(void);
void drawLine(int x0, int y0,int xEnd,int yEnd);
void setpixel(int x, int y);

void MyMouse(int button, int state, int x, int y);
void MyMouseMotion(int x,int y);
void MyKeyboard(unsigned char key, int x, int y);
void MySpecialKey(int key, int x, int y);

void MyCreateMenu();
void MajorMenu(int value);
void colorMenu(int value);
void linewidthMenu(int value);
void moveSpeedMenu(int value);

int main(int argc, char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(500,500);
glutInitWindowPosition(500,300);
glutCreateWindow("实验2 利用鼠标、键盘，菜单等方式对图元进行交互操作");

init();
MyCreateMenu();
glutReshapeFunc (MyReshape);
//glutIdleFunc(MyIdle);

glutDisplayFunc(display);
glutMouseFunc (MyMouse);
glutMotionFunc(MyMouseMotion);

glutKeyboardFunc (MyKeyboard);
glutSpecialFunc(MySpecialKey);
glutMainLoop();
}

void display(void)
{
cout<<"Displaying... ";
glClear(GL_COLOR_BUFFER_BIT);
glFlush();
cout<<"Displayed! "<<endl;
}

void MyCreateMenu()
{
int majorMenuID = glutCreateMenu(MajorMenu);
int colorMenuID = glutCreateMenu(colorMenu);
int linewidthMenuID = glutCreateMenu(linewidthMenu);
int moveSpeedMenuID = glutCreateMenu(moveSpeedMenu);

glutSetMenu(majorMenuID);//设置当前菜单
glutAttachMenu(GLUT_RIGHT_BUTTON);//绑定到鼠标右键
glutAddSubMenu("颜色变化",colorMenuID);
glutAddSubMenu("粗细变化",linewidthMenuID);
glutAddSubMenu("移动速度变化",moveSpeedMenuID);

glutAddMenuEntry("清屏", 3);
glutAddMenuEntry("退出", 4);

glutSetMenu(colorMenuID);
glutAddMenuEntry("红色", 1);
glutAddMenuEntry("绿色", 2);
glutAddMenuEntry("蓝色", 3);

glutSetMenu(linewidthMenuID);
glutAddMenuEntry("设为1", 1);
glutAddMenuEntry("设为3", 2);
glutAddMenuEntry("设为5", 3);

glutSetMenu(moveSpeedMenuID);
glutAddMenuEntry("设为1", 1);
glutAddMenuEntry("设为3(默认)", 2);
glutAddMenuEntry("设为5", 3);

return;
}

void MajorMenu(int value)
{
switch(value)
{
case 3:
{
glClear(GL_COLOR_BUFFER_BIT);
glFlush();
break;
}

case 4:
exit(0);
}
return;
}

void colorMenu(int value)
{
cout<<"颜色设置中.........."<<endl;
switch(value)
{
case 1:
glColor3f(1.0, 0.0, 0.0);
break;
case 2:
glColor3f(0.0, 1.0, 0.0);
break;
case 3:
glColor3f(0.0, 0.0, 1.0);
break;
}
drawLine(x0,y0,xEnd,yEnd);
return;
}

void linewidthMenu(int value)
{
cout<< "线宽设置中.........."<<endl;
switch(value)
{
case 1:
glLineWidth(1);
break;
case 2:
glLineWidth(3);
break;
case 3:
glLineWidth(5);
break;
}
drawLine(x0,y0,xEnd,yEnd);
return;
}

void moveSpeedMenu(int value)
{
cout<< "移动速度设置中.........."<<endl;
switch(value)
{
case 1:
moveSpeed = 1;
break;
case 2:
moveSpeed = 3;
break;
case 3:
moveSpeed = 5;
break;
}
return;
}

void MyMouse(int button, int state, int x, int y)
{
if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
cout<<"左键被按下 ";
x0 = x;
y0 = WINHEIGHT - y;
setpixel(x0,y0);
FirstPointHadDraw = true;
}
if(button == GLUT_LEFT_BUTTON &&state == GLUT_UP)
{
cout<<"左键被释放 "<<endl;
LineHadDraw = true;
}
}

//移动事件键被按下的同时发生移动
void MyMouseMotion(int x,int y)
{
cout<<"鼠标移动中... ";
if(true ==FirstPointHadDraw)
{
xEnd = x;
yEnd = WINHEIGHT - y;
drawLine(x0,y0,xEnd,yEnd);
}
return;
}

void drawLine(int x, int y,int x2,int y2)
{
cout<<"准备画线:"<< x0<<" "<< y0<<" " << xEnd<<" "<< yEnd<<" "<<endl;
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_LINES);
glVertex2f(x,y);
glVertex2f(x2,y2);
glEnd();

cout<<"画线完成 ";
glFlush();
return;
}

void MyKeyboard(unsigned char key, int x, int y)
{
//27为ESC键
if(key==27)
{
exit(0);
}
}

void MySpecialKey(int key, int x, int y)
{
glutGetModifiers();
switch(key)
{
case GLUT_KEY_UP:
{
y0 += moveSpeed;
yEnd += moveSpeed;
break;
}
case GLUT_KEY_DOWN:
{
y0 -= moveSpeed;
yEnd -= moveSpeed;
break;
}
case GLUT_KEY_LEFT:
{
x0 -= moveSpeed;
xEnd -= moveSpeed;
break;
}
case GLUT_KEY_RIGHT:
{
x0 += moveSpeed;
xEnd += moveSpeed;
break;
}
}

drawLine(x0,y0,xEnd,yEnd);
return;
}

//返回调整大小后的窗口大小 w，h
void MyReshape(GLsizei w, GLsizei h)
{
//view port 左下角为0,0
//窗口在高度方向变长，截图也要在该方向上拉长相同比例
//宽度方向拉长，截图也要在该方向上拉长相同比例
cout<<"Reshaping... "<<w<<" "<<h;

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

if(w<=h)
gluOrtho2D(0,500, 0,500 * h/w);
else
gluOrtho2D(0,500 * w/h, 0,500);
glViewport(0,0,w,h);

WINWIDTH = w;
WINHEIGHT = h;
cout<<"Reshaped"<<endl;
}

void setpixel(int x, int y)
{
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
return;
}

void MyIdle()
{
glutPostRedisplay();
}

void init()
{
//反射任何光，为白色
//gluOrtho2D(left, right, bottom, top);
//glortho(x_min x_max y_min y_max near top)

cout<<"Initing... ";
glClearColor (1.0, 1.0, 1.0, 1.0);
glColor3f(0.0, 0.0, 0.0);
glPointSize(2.0);
glLineWidth(2.0);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho(0.0f, WINWIDTH, 0.0f, WINHEIGHT, 1.0, -1.0);

cout<<"Inited!"<<endl;
}

OpenGL实验二 利用鼠标、键盘，菜单等方式对图元进行交互操作

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