#include <GL/glut.h>

float posX = 0.0f, posY = 0.0f; // 方块位置
const float step = 0.05f;        // 移动步长
const float size = 0.2f;         // 方块半边长

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    
    // 绘制方块
    glPushMatrix();
    glTranslatef(posX, posY, 0.0f);
    glColor3f(0.0f, 0.8f, 1.0f); // 青色方块
    glBegin(GL_QUADS);
        glVertex2f(-size, -size);
        glVertex2f( size, -size);
        glVertex2f( size,  size);
        glVertex2f(-size,  size);
    glEnd();
    glPopMatrix();
    
    glutSwapBuffers();
}

void reshape(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-1.0, 1.0, -1.0, 1.0); // 坐标系范围
}

void keyboard(int key, int x, int y) {
    // 边界检测（防止移出窗口）
    switch(key) {
        case GLUT_KEY_LEFT:
            if(posX - size > -1.0f) posX -= step;
            break;
        case GLUT_KEY_RIGHT:
            if(posX + size < 1.0f) posX += step;
            break;
        case GLUT_KEY_UP:
            if(posY + size < 1.0f) posY += step;
            break;
        case GLUT_KEY_DOWN:
            if(posY - size > -1.0f) posY -= step;
            break;
    }
    glutPostRedisplay();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(600, 600);
    glutCreateWindow("Keyboard Control");
    
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutSpecialFunc(keyboard); // 注册特殊按键回调
    
    glClearColor(0.2f, 0.2f, 0.2f, 1.0f); // 深灰色背景
    
    glutMainLoop();
    return 0;
}