【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 3int 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,rcase 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);elserotate2D(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,rcase 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();}