【计算机图形学】c++ OpenGL 二维变换（包括多边形绘制、平移、旋转及缩放）

运行结果演示

源代码

// 二维变换.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<GL/glut.h>
#include<GL/gl.h>
#include<GL/glu.h>
#include<iostream>
#include<cmath>
#include<vector>

#define PI 3.14159265358
//q,w,e,r分别为平移，绘制多边形，旋转，缩放
#define TRANSLATE 0
#define DRAWPOLYGON 1
#define ROTATE 2
#define SCALE 3
int tran_x,tran_y;
int _xtmp,_ytmp;//作为缩放变量用
int mode=DRAWPOLYGON;//默认为绘制模式
using namespace std;
const int winwidth=800;
const int winheight=640;

struct position{
    double x;
    double y;
};

typedef GLfloat Matrix3x3[3][3];
Matrix3x3 matComposite;//复合矩阵
vector<position> xy;
position tmp;
void DrawPolygon();
void dragmouse(int x,int y);
void mymouse(int button,int state,int x,int y);
void myKeyboard(unsigned char key,int x,int y);
void myKeyboardUp(unsigned char key,int x,int y);

//设置为单位矩阵
void matrix3x3SetIdentity(Matrix3x3 mat){
    GLint row,col;
    for(row=0;row<3;row++){
        for(col=0;col<3;col++)
            mat[row][col]=(row==col);
    }
}

void init(){
    glClearColor(1.0,1.0,1.0,1.0);//设置绘制窗口颜色为白色
    glClear(GL_COLOR_BUFFER_BIT);//清除窗口显示内容
    /*设置为投影类型模式和其他观察参数*/
    glPointSize(3.0f);
    glColor3f(1.0,0.0,0.0);//设置颜色为红
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0,winwidth,winheight,0);
    matrix3x3SetIdentity(matComposite);
}

 

//矩阵相乘
void matrixpreMultiply(Matrix3x3 m1,Matrix3x3 m2){
    GLint row,col;
    Matrix3x3 tmp;
    for(row=0;row<3;row++){
        for(col=0;col<3;col++){
            tmp[row][col]=m1[row][0]*m2[0][col]+m1[row][1]*
                m2[1][col]+m1[row][2]*m2[2][col];
        }
    }

    for(row=0;row<3;row++){
        for(col=0;col<3;col++){
            m2[row][col]=tmp[row][col];
        }
    }
}

//平移
void translate2D(GLfloat tx,GLfloat ty){
    Matrix3x3 matTransl;
    matrix3x3SetIdentity(matTransl);//设置为单位矩阵
    matTransl[0][2]=tx;
    matTransl[1][2]=ty;
    matrixpreMultiply(matTransl,matComposite); 
}

//旋转
void rotate2D(int x,int y,float theta){
    theta=theta/180*PI;
    Matrix3x3 matRot;
    matrix3x3SetIdentity(matRot);
    matRot[0][0]=cos(theta);
    matRot[0][1]=-sin(theta);
    matRot[0][2]=x*(1-cos(theta))+y*sin(theta);
    matRot[1][0]=sin(theta);
    matRot[1][1]=cos(theta);
    matRot[1][2]=y*(1-cos(theta))-x*sin(theta);
    matrixpreMultiply(matRot,matComposite);
}

 
//缩放
void scale2D(GLfloat sx,GLfloat sy,int x,int y){
    Matrix3x3 matScale;
    matrix3x3SetIdentity(matScale);
    matScale[0][0]=sx;
    matScale[0][2]=(1-sx)*x;
    matScale[1][1]=sy;
    matScale[1][2]=(1-sy)*y;
    matrixpreMultiply(matScale,matComposite);
}

//复合矩阵
void transformVerts2D(){
    GLfloat tmp;
    for(int i=0;i<xy.size();i++){
        tmp=matComposite[0][0]*xy[i].x+matComposite[0][1]*xy[i].y+matComposite[0][2];
        xy[i].y=matComposite[1][0]*xy[i].x+matComposite[1][1]*xy[i].y+matComposite[1][2];
        xy[i].x=tmp;
    }
    DrawPolygon();
    matrix3x3SetIdentity(matComposite);
}
 

//绘制多边形
void DrawPolygon(){
//  glEnable(GL_POLYGON_STIPPLE);
    glPolygonMode(GL_BACK,GL_LINE);//设置反面为线性模式
    glPolygonMode(GL_FRONT,GL_LINE);//设置正面为线性模式
    glClear(GL_COLOR_BUFFER_BIT);//清除窗口显示内容
    glBegin(GL_POLYGON);
    for(unsigned int i=0;i<xy.size();i++){
        glVertex2f(xy[i].x,xy[i].y);
    }
    glEnd();
    glFlush();
}

//鼠标拖动
void dragmouse(int x,int y){
    float ssx=1,ssy=1;
    switch (mode)
    {
        //q,w,e,r
        case TRANSLATE:
            translate2D(x-tran_x,y-tran_y);
            transformVerts2D();
            tran_x=x;
            tran_y=y;
            break;
        case DRAWPOLYGON:               
            break;
        case ROTATE:
            if(x<=_xtmp&&y>=_ytmp)
                rotate2D(tran_x,tran_y,-8);
            else
                rotate2D(tran_x,tran_y,8);
            transformVerts2D();
            _xtmp=x;
            _ytmp=y; 
            break;
        case SCALE:  

            /*不等比例缩放*/
            if(x>_xtmp){
                ssx+=0.01f;
            }
            else if(x<_xtmp&&ssx>0){
                ssx-=0.01f;
            }
            if(y<_ytmp){
                ssy+=0.01f;
            }
            else if(y>_ytmp&&ssy>0){
                ssy-=0.01f;
            }

            /*等比例缩放

            if(x<=_xtmp&&y>=_ytmp){

                ssx-=0.01f;

                ssy-=0.01f;

            }else{

                ssx+=0.01f;

                ssy+=0.01f;

            }*/

            scale2D(ssx,ssy,tran_x,tran_y);
            transformVerts2D();
            _xtmp=x;
            _ytmp=y;
            break;
        default:
            break;
    } 
} 

//鼠标
void mymouse(int button,int state,int x,int y){
 
    if(button==GLUT_LEFT_BUTTON &&state==GLUT_DOWN){
        switch (mode)
        {
        //q,w,e,r
        case TRANSLATE:
            tran_x=x;
            tran_y=y;
            break;
        case DRAWPOLYGON:      
            tmp.x=x;
            tmp.y=y;
            xy.push_back(tmp);
            DrawPolygon();
            break;
        case ROTATE:
            tran_x=x;
            tran_y=y;
            _xtmp=x;
            _ytmp=y;
            break;
        case SCALE:
            tran_x=x;
            tran_y=y;
            break;
        default:
            break;
        } 
    }
   
}

//键盘
void myKeyboard(unsigned char key,int x,int y){
    //清空删除
    if(key=='a'){
        glClear(GL_COLOR_BUFFER_BIT);//清除窗口显示内容
        glFlush();
        xy.clear();
    }
}

 

void myKeyboardUp(unsigned char key,int x,int y){
    switch (key)
    {
    case 'q':mode=TRANSLATE;
        break;
    case 'w':mode=DRAWPOLYGON;
        break;
    case 'e':mode=ROTATE;
        break;
    case 'r':mode=SCALE;
        break;
    default:
        break;
    }
}

void myDisplay(){
     glFlush();
}

void mymenu(int id){
    if(id==0)
        mode=0;
    else if(id==1)
       mode=1;
    else if(id==2)
        mode=2;
    else if(id==3)
        mode=3;
}
 
int main(int argc,char**argv){
    glutInit(&argc,argv);//初始化
    glutInitDisplayMode(GLUT_SINGLE |GLUT_RGB);//设置绘制模式
    glutInitWindowPosition(500,300);
    glutInitWindowSize(winwidth,winheight);
    glutCreateWindow("二维图形的变换");//创建窗口 
    int id=glutCreateMenu(mymenu);   
    glutAddMenuEntry("平移",0);
    glutAddMenuEntry("绘制多边形",1);
    glutAddMenuEntry("旋转",2);
    glutAddMenuEntry("缩放",3);
    glutAttachMenu(GLUT_RIGHT_BUTTON);
    init();
    glutDisplayFunc(myDisplay);
    glutMouseFunc(mymouse);//鼠标监听回调函数
    glutMotionFunc(dragmouse);//鼠标拖动 
    glutKeyboardFunc(myKeyboard);//键盘监听
    glutKeyboardUpFunc(myKeyboardUp);//键盘弹起状态
    glutMainLoop();
}