Question

在我使用freeglut的openGL程序中，屏幕完全被这段代码所取代：

glBegin(GL_QUADS);   
    glPushMatrix();
        glVertex3f(trackRadius*cos((double)x), trackHeight*sin(trackNumberOfHills*x), trackRadius*sin(x));
        glVertex3f((trackRadius+1)*cos((double)x), trackHeight*sin(trackNumberOfHills*x), (trackRadius+1)*sin(x));
        glVertex3f(trackRadius*cos((double)x+(0.005)), trackHeight*sin(trackNumberOfHills*(x+0.005)), trackRadius*sin(x+0.005));
        glVertex3f((trackRadius+1)*cos((double)x+0.005), trackHeight*sin(trackNumberOfHills*(x+0.005)), (trackRadius+1)*sin(x+0.005));
    glPopMatrix();
glEnd();

以上代码用于显示两条铁轨之间的线路，当上面的代码被移除时，这两条铁轨的生成和显示都很好。卡丁车也很好。

我发现如果我删除了glPushMatrix（）;和glPopMatrix（）;一切都很好，但我需要矩阵推/弹线不是吗？

编辑1：这是我调用的完整代码，用于在我的主要过剩.cpp

调用的类Track.cpp中显示我的音轨

void Track::RenderTrack() 
{
double x=-3.14;
glNewList(1, GL_COMPILE);  // create sphere display list for Object 1
glutSolidSphere(0.1,20,20); 
glEndList();

glNewList(2, GL_COMPILE);
for (x; x<3.14;x= x+.005)
{
//first track
glPushMatrix();
glColor3f(1.0,0.0,0.0);
glTranslatef(trackRadius*cos((double)x),trackHeight * sin((double)trackNumberOfHills*x),trackRadius*sin((double)x));
glCallList(1);
glPopMatrix();

//Second track
glPushMatrix();
glColor3f(0.0,1.0,0.0);
glTranslatef((trackRadius+1)*cos(x),trackHeight * sin(trackNumberOfHills*x),(trackRadius+1)*sin(x));
glCallList(1);
glPopMatrix();


//Track Insides
glBegin(GL_QUADS);   
glPushMatrix();
glVertex3f(trackRadius*cos((double)x), trackHeight*sin(trackNumberOfHills*x), trackRadius*sin(x));
glVertex3f((trackRadius+1)*cos((double)x), trackHeight*sin(trackNumberOfHills*x), (trackRadius+1)*sin(x));
glVertex3f(trackRadius*cos((double)x+(0.005)), trackHeight*sin(trackNumberOfHills*(x+0.005)), trackRadius*sin(x+0.005));
glVertex3f((trackRadius+1)*cos((double)x+0.005), trackHeight*sin(trackNumberOfHills*(x+0.005)), (trackRadius+1)*sin(x+0.005));
glPopMatrix();
glEnd();
}
glEndList();

glCallList(2); // call the list to draw it

}

Answer 1

来自opengl文档：

glBegin和glEnd之间只能使用GL命令的子集。命令是glVertex，glColor，glSecondaryColor，glIndex，glNormal，glFogCoord，glTexCoord，glMultiTexCoord，glVertexAttrib，glEvalCoord，glEvalPoint，glArrayElement，glMaterial和glEdgeFlag。此外，可以使用glCallList或glCallLists来执行仅包含前面命令的显示列表。如果在glBegin和glEnd之间执行任何其他GL命令，则设置错误标志并忽略该命令。

glPushMatrix和glPopMatrix不在此列表中，因此您的代码将被忽略。

您可以将它们放在glBegin / glEnd块之外。

OpenGL白屏

1 个答案: