openGL实现平行投影和透视投影完整代码

以下是使用OpenGL实现平行投影和透视投影的完整代码示例：

平行投影：

#include <GL/glut.h>

void init() {
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
}

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glBegin(GL_POLYGON);
    glVertex3f(-0.5, -0.5, 0.0);
    glVertex3f(-0.5, 0.5, 0.0);
    glVertex3f(0.5, 0.5, 0.0);
    glVertex3f(0.5, -0.5, 0.0);
    glEnd();
    glFlush();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Parallel Projection");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}

透视投影：

#include <GL/glut.h>

void init() {
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60.0, 1.0, 0.1, 100.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}

void display() {
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glutWireTeapot(1.0);
    glFlush();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB|GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Perspective Projection");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}