未绘制OpenGL四边形

我试图在屏幕上画一个四边形（正方形）。我将其插入到一个预先存在的程序中，该程序绘制了一个圆柱体。这是在正交模型视图矩阵中，我几乎可以肯定剪裁体积是正确的（从原点到任意方向都是200）。在我使用的显示函数中，我按下一个矩阵，向前转换（0.0,0.0，-20.0），称为quadriliteral，然后弹出该矩阵。我不知道人们使用的任何常见openGL设置是否会使其不可见？有没有办法获取当前剪辑卷并在控制台中打印出来

void quadrilateral() 
{
    glLoadIdentity();
    glColor3f(0.5f,0.0f,0.8f);
    glBegin(GL_QUADS);

    glVertex3f(-10.0f,-10.0f,0.0f);
    glVertex3f(-10.0f,10.0f,0.0f);
    glVertex3f(10.0f,10.0f,0.0f);
    glVertex3f(10.0f,-10.0f,0.0f);

    glEnd();
}


//This is called from a main function elsewhere
void draw(void)
{
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500); 
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Cylinder");
    glutReshapeFunc(CChangeSize);
    glutSpecialFunc(CSpecialKeys);
    glutKeyboardFunc(Ckeyboard);
    glutDisplayFunc(CRenderScene);
    CSetupRC();
    glPopMatrix();
}


void CSetupRC()
{
// Light values and coordinates
GLfloat  ambientLight[] = {0.4f, 0.4f, 0.4f, 1.0f };
GLfloat  diffuseLight[] = {0.7f, 0.7f, 0.7f, 1.0f };
GLfloat  specular[] = { 0.9f, 0.9f, 0.9f, 1.0f};
GLfloat  lightPos[] = { -50.0f, 200.0f, 200.0f, 1.0f };
GLfloat  specref[] =  { 0.6f, 0.6f, 0.6f, 1.0f };


glEnable(GL_DEPTH_TEST);    // Hidden surface removal
glEnable(GL_CULL_FACE);     // Do not calculate inside of solid object
glFrontFace(GL_CCW);

// Enable lighting
glEnable(GL_LIGHTING);

// Setup light 0
glLightModelfv(GL_LIGHT_MODEL_AMBIENT,ambientLight);
glLightfv(GL_LIGHT0,GL_AMBIENT,ambientLight);
glLightfv(GL_LIGHT0,GL_DIFFUSE,diffuseLight);
glLightfv(GL_LIGHT0,GL_SPECULAR,specular);

// Position and turn on the light
glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
glEnable(GL_LIGHT0);

// Enable color tracking
glEnable(GL_COLOR_MATERIAL);

// Set Material properties to follow glColor values
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);

// All materials hereafter have full specular reflectivity
// with a moderate shine
glMaterialfv(GL_FRONT, GL_SPECULAR,specref);
glMateriali(GL_FRONT,GL_SHININESS,64);

// Black background
glClearColor(0.0f, 0.0f, 0.0f, 0.0f );


glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glEnable(GL_TEXTURE_2D);

}


// Called to draw scene
void CRenderScene(void)
{
// Clear the window with current clearing color
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Save the matrix state
glMatrixMode(GL_MODELVIEW);
glPushMatrix();

// Rotate about x and y axes
glRotatef(CxRot, 1.0f, 0.0f, 0.0f);
glRotatef(CyRot, 0.0f, 1.0f, 0.0f);

// Draw the cylinder
cylinder();

glPopMatrix();

// CylinderTwo
glMatrixMode(GL_MODELVIEW);
glPushMatrix();

// Rotate about x and y axes
glRotatef(CxRot, 1.0f, 0.0f, 0.0f);
glRotatef(CyRot, 0.0f, 1.0f, 0.0f);

// Draw the cylinder
glRotatef(120.0f, 1.0f, 1.0f, 1.0f);
cylinderTwo();

glPopMatrix();

// Random square
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslatef(-30.0f,20.0f,10.0f);
quadrilateral();
glPopMatrix();

// Swap buffers
glutSwapBuffers();

---

}

我看你的四线组是向后缠绕的。您已经启用了GL_CULL_FACE，它会抛出任何顺时针缠绕的多边形，并且您的四边形具有顺时针缠绕

---

禁用背面消隐，或将顶点顺序切换为逆时针方向。

看起来缠绕顺序不正确：

glEnable(GL_CULL_FACE);

这条线意味着它将剔除背面

glFrontFace(GL_CCW);

这将正面设置为逆时针方向

    glVertex3f(-10.0f,-10.0f,0.0f);
    glVertex3f(-10.0f,10.0f,0.0f);
    glVertex3f(10.0f,10.0f,0.0f);
    glVertex3f(10.0f,-10.0f,0.0f);

在这里，顶点按顺时针顺序排列，这意味着您正在使用背对摄影机进行绘制。禁用消隐：

    glDisable(GL_CULL_FACE);

使正面顺时针旋转：

    glFrontFace(GL_CW);

---

或者将顶点的顺序更改为逆时针顺序。

能否继续并发布所有相关的OpenGL初始化代码？（如果您不熟悉网站，请在帖子上查找编辑按钮）。有大约100种不同的方式可以让你陷入困境，所以如果我们不必猜测，这可能是最好的。欢迎来到SO。当然，它很长，但我会尽量缩短。不要让它比需要的长，但如果你不确定某件事是否重要，那就错在分享过度。我尝试了上述所有方法，但可惜，它仍然不会出现：（一定还有其他问题