GLUT只是渲染一個空白的白色屏幕？

Question

這裏是代碼，沒有任何錯誤，它有什麼問題？

我編譯它，命令提示符打開，窗口打開，窗口全白，我把它重新着色成灰色，並且它也沒有畫出我的形狀，那麼問題是什麼？

#ifdef __APPLE__ 
    #include <GLUT/glut.h> 
    #else 
    #include <GL/glut.h> 
    #endif 

    #include <stdlib.h> 



    void ProcessSpecialKeys(int key, int x, int y){ 

     switch(key){ 

      case GLUT_KEY_RIGHT: 


    exit(0); 



      case GLUT_KEY_LEFT: 

    exit(0); 

      case GLUT_KEY_UP: 
    exit(0); 

      case GLUT_KEY_DOWN: 

    exit(0); 
      default: 

    exit(0); 

     } 




     } 



    void renderScene(void) { 
    glClearColor(0.3f, 0.3f, 0.3f, 0.3f); 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 


     glutSwapBuffers(); 
} 

    void renderPrimitive(void){ 
    glBegin(GL_QUADS); 
    glVertex3f(-1.0f,-1.0f,0.0f); 
    glVertex3f(-1.0f,1.0f,0.0f); 
    glVertex3f(1.0f,1.0f,0.0f); 
    glVertex3f(1.0f,-1.0f,0.0f); 
    glEnd(); 
} 

    void display(void){ 
    glTranslatef(0.0f,0.0f,-0.5f); 
    renderPrimitive(); 
    glFlush(); 
    glClearColor(0.3f,0.3f,0.3f,0.3f); 
    glClear(GL_COLOR_BUFFER_BIT); 
} 

int main(int argc, char **argv) { 

    glutInit(&argc, argv); 
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); 
    glutInitWindowPosition(100,100); 
    glutInitWindowSize(320,320); 
    glutCreateWindow("Dimension"); 
    glutDisplayFunc(display); 

    glLoadIdentity(); 

glutSpecialFunc(ProcessSpecialKeys); 


    glutMainLoop(); 

    return 1; 
} 

Answer 1

問題是您在顯示功能中繪製場景後清除顯示。另外，還有一個無用的電話glFlush()。刪除這些行：

glFlush(); 
glClearColor(0.3f,0.3f,0.3f,0.3f); 
glClear(GL_COLOR_BUFFER_BIT); 

添加glutSwapBuffers()而不是他們。

glFlush()用於單緩衝模式。

請記住，您正在使用雙緩衝模式，所以有兩個緩衝區。你的場景被繪製到後臺緩衝區，並顯示它，你必須通過在顯示功能結束時調用glutSwapBuffers()將它複製到前臺緩衝區。

Answer 2

試試這個：

#include <GL/glut.h> 
#include <stdlib.h> 

void ProcessSpecialKeys(int key, int x, int y) 
{ 
    switch(key) 
    { 
    case GLUT_KEY_RIGHT: 
    case GLUT_KEY_LEFT: 
    case GLUT_KEY_UP: 
    case GLUT_KEY_DOWN: 
     exit(0); 
     break; 
    default: 
     exit(0); 
     break; 
    } 
} 

void renderPrimitive() 
{ 
    glBegin(GL_QUADS); 
    glVertex3f(-1.0f,-1.0f,0.0f); 
    glVertex3f(-1.0f,1.0f,0.0f); 
    glVertex3f(1.0f,1.0f,0.0f); 
    glVertex3f(1.0f,-1.0f,0.0f); 
    glEnd(); 
} 

void display() 
{ 
    glClearColor(0.3f,0.3f,0.3f,0.3f); 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    glOrtho(-2, 2, -2, 2, -1, 1); 

    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity(); 

    glPushMatrix(); 
    glTranslatef(0.0f,0.0f,-0.5f); 
    renderPrimitive(); 
    glPopMatrix(); 

    glutSwapBuffers(); 
} 

int main(int argc, char **argv) 
{ 
    glutInit(&argc, argv); 
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); 
    glutInitWindowPosition(100,100); 
    glutInitWindowSize(320,320); 
    glutCreateWindow("Dimension"); 
    glutDisplayFunc(display); 
    glutSpecialFunc(ProcessSpecialKeys); 
    glutMainLoop(); 
    return 1; 
}