OpenGL 2D旋转问题

Posted 2023-02-22

【中文标题】OpenGL 2D旋转问题

【英文标题】：OpenGL 2D rotation problem

【发布时间】：2011-05-10 13:11:46

【问题描述】：

在下面的程序中，我试图画一个简单的房子。坐标在房屋数组中定义。我需要旋转房子并显示旋转的房子和原来的房子。 但是为什么旋转的房子没有显示出来呢？

    //Program to create a house like figure and rotate ir about a given fixed point using OpenGL functions.
#include <glut.h>
#include <stdio.h>

float house [11][2] = 100,200,200,250,300,200,100,200,100,100,175,100,175,150,225,150,225,100,300,100,300,200;

void init()

    glClearColor(1,1,1,0);
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0,800,0,800);
    glMatrixMode(GL_MODELVIEW);


void display()

    glClear(GL_COLOR_BUFFER_BIT);

    //NORMAL HOUSE
    glColor3f(1,0,0);
    glBegin(GL_LINE_LOOP);

    for(int i=0;i<11;i++)
        glVertex2fv(house[i]);
    glEnd();
    glFlush();


    //ROTATED HOUSE
    glPushMatrix();
    glRotatef(60,0,1,0);
    glColor3f(1,1,0);
    glBegin(GL_LINE_LOOP);

    for(int i=0;i<11;i++)
        glVertex2fv(house[i]);
    glEnd();
    glFlush();
    glPopMatrix();


void main(int argc,char** argv)

    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(800,800);
    glutInitWindowPosition(100,100);
    glutCreateWindow("House rotation");
    init();
    glutDisplayFunc(display);
    glutMainLoop();

【参考方案1】：

尝试在 Z 轴而不是 Y 轴上旋转：

//Program to create a house like figure and rotate ir about a given fixed point using OpenGL functions.
#include <GL/glut.h>

float house [11][2] = 100,200,200,250,300,200,100,200,100,100,175,100,175,150,225,150,225,100,300,100,300,200;

void display()

    glClearColor(1,1,1,0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0,800,0,800);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    //NORMAL HOUSE
    glColor3f(1,0,0);
    glBegin(GL_LINE_LOOP);
    for(int i=0;i<11;i++)
        glVertex2fv(house[i]);
    glEnd();


    //ROTATED HOUSE
    glPushMatrix();
    glTranslatef(100,100,0);
    glRotatef(60,0,0,1);
    glTranslatef(-100,-100,0);
    glColor3f(1,1,0);
    glBegin(GL_LINE_LOOP);
    for(int i=0;i<11;i++)
        glVertex2fv(house[i]);
    glEnd();
    glPopMatrix();


void main(int argc,char** argv)

    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(800,800);
    glutInitWindowPosition(100,100);
    glutCreateWindow("House rotation");
    glutDisplayFunc(display);
    glutMainLoop();

编辑：这个应该围绕底角旋转。

【讨论】：

以上修改显示输出。但它不会围绕位于 100,100 的左下角旋转房子。所以我尝试了这个： glTranslatef(-100,-100,0); glRotatef(30,0,0,1); glTranslatef(100,100,0);但它仍然不起作用。为什么？

@footy：已编辑。看起来这些转换的顺序有误。