潛在的bug openGL

我正在嘗試使用菜單在屏幕上平鋪圖像。我的菜單工作 - 以適當的方式平鋪 - 直到我移動鼠標，然後平鋪設計消失？潛在的bug openGL

#include <GL/glut.h>  
#include <fstream>  
#include <cstdlib> 
#include "TUGL.h" 
#include <glui.h> 

//Global variables 

class GLintPoint 
{ 
    public: 
    GLint x; 
    GLint y; 
}; 

GLint numpoints;  
GLintPoint P[10];  


window Win(800,600); 
frame Frame; 
GLUI *glui; 
int mainwindow; 

//Function prototypes 

void readinpoints();     
void drawline(GLint from, GLint to); 
void display(void);     
void init (void);      
void keyboard(unsigned char key, int x, int y); 
void tile1(void); 
void tile4(void); 
void tile9(void); 
void tile16(void); 
void myReshape(GLsizei W, GLsizei H); 
void define_glui_window(); 
void choice_selected(int value); 
void drawImage(void); 
//Main 

int main(int argc, char** argv) 
{ 
    glutInit(&argc, argv); 
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); 
    glutInitWindowSize (Win.width, Win.height); 
    glutInitWindowPosition (100, 100); 
    mainwindow = glutCreateWindow ("*star*"); 

    init(); 
    define_glui_window(); 
    glutDisplayFunc(display); 
    glutKeyboardFunc(keyboard); 
    glutReshapeFunc(myReshape); 
    readinpoints(); 

    glutMainLoop(); 
    return 0; 
} 

//Functions 

void init (void) 
{ 
    glClearColor (0.0, 0.0, 0.0, 0.0); //set background color 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    glOrtho(0.0, 200, 0.0, 249, -1.0, 1.0); 

} 

void readinpoints() 

{ 
    ifstream infile("polyline.pts"); 

    numpoints=0; 
    infile>>P[numpoints].x>>P[numpoints].y; 
    while (!infile.eof()) 
    { 
    numpoints++; 
    infile>>P[numpoints].x>>P[numpoints].y; 
    } 
    numpoints=numpoints-1; 
} 

void drawline(GLint from, GLint to) 

{ 
    glBegin(GL_LINES); 
    { 
    glVertex2i(P[from].x, P[from].y); 
    glVertex2i(P[to].x, P[to].y); 
    } 
    glEnd(); 
} 

void drawImage(void); 
{ 
    glClear (GL_COLOR_BUFFER_BIT) 
    glColor3f (1.0, 0.0, 1.0);  
    glLineWidth(3); 

    drawline(0,1);   
    drawline(1,2);  
    drawline(2,3);   
    drawline(3,4); 
    drawline(4,5); 
    drawline(5,6); 
    drawline(6,7); 
    drawline(7,8); 
    drawline(8,9); 
    drawline(9,0); 

    glFlush(); 

} 

void display(void) 

{ 
    glClear (GL_COLOR_BUFFER_BIT); 
    //autoViewPort(Frame, Win); 
    drawImage();    
} 

void tile1(void) 

{ glClear (GL_COLOR_BUFFER_BIT); 
    for(int i=0; i < 1; i++) 
     for(int j=0; j < 1; j++) 
     { 
      //autoViewPort(Frame, Win); 
      glViewport(i * 800, j * 600, 800, 600); 
      drawImage(); 
      glFlush(); 
     } 
} 
void tile4(void) 

{ glClear (GL_COLOR_BUFFER_BIT); 
    for(int i=0; i < 2; i++) 
     for(int j=0; j < 2; j++) 
     { 
     // autoViewPort(400, 300); 
      glViewport(i * 400, j * 300, 400, 300); 
      drawImage(); 
        glFlush(); 
     } 
} 
void tile9(void) 

{ 
    glClear (GL_COLOR_BUFFER_BIT); 
    for(int i=0; i < 3; i++) 
     for(int j=0; j < 3; j++) 
     { 
     // autoViewPort(267, 200); 
      glViewport(i * 267, j * 200, 267, 200); 
      drawImage(); 
        glFlush(); 
     } 
} 
void tile16(void) 
{ 
    glClear (GL_COLOR_BUFFER_BIT); 
    for(int i=0; i < 4; i++) 
     for(int j=0; j < 4; j++) 
     { 
     // autoViewPort(200, 150); 
      glViewport(i * 200, j * 150, 200, 150); 
      drawImage(); 
        glFlush(); 
     } 
} 
void keyboard(unsigned char key, int x, int y) 
{ 
    switch (key) {   
     case 27:  
     exit(0); 
     break; 
     case 'f': 

    tile4(); 
    break; 
    case 'n': 
    tile9(); 
    break; 
    case 's': 
    tile16(); 
    break; 
    case 'o': 
    tile1(); 
    break; 
    } 
} 
void myReshape(GLsizei W, GLsizei H) 

{ 
    Win.set(W,H); 
    autoViewPort(Frame, Win); 
} 

void choice_selected(int value) 

{ 
    switch (value) 
    { 
    case 1: 
     tile1(); 
     break; 
    case 2: 
     tile4(); 
     break; 
    case 3: 
     tile9(); 
     break; 
    case 4: 
     tile16(); 
     break; 
    } 
} 

void define_glui_window() 
{ 
    glui = GLUI_Master.create_glui("OPTIONS", 0, 560, 50); 

    GLUI_StaticText *message1 = glui->add_statictext(" BACKGROUND COLOR "); 
    glui->add_button("Tile-1", 1, choice_selected); 
    glui->add_button("Tile-4", 2, choice_selected); 
    glui->add_button("Tile-9", 3, choice_selected); 
    glui->add_button("Tile-16", 4, choice_selected); 
    glui->set_main_gfx_window(mainwindow); 
    GLUI_Master.sync_live_all(); 
}

來源

2010-09-28 Alison Ridgway