Question

我正在尝试制作一个非常简单的MFC OpenGL教程有一个球体。而spere是光源（如太阳）。并且有两个三角形。根据法术的运动，我想让三角形变亮但是当我移动球体时，三角形的表面只是第一次发生变化球体的下一次移动不会改变三角形的表面。

如何保持光线位置的痕迹？
这是keyborad处理函数。

void CView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
    if (nChar == VK_UP)
    {
        m.x += 0.1f;
    }
    else if (nChar == VK_DOWN)
    {
        m.y -= 0.1f;
    }
    else if (nChar == VK_LEFT)
    {
        m.x -= 0.1f;
    }
    else if (nChar == VK_RIGHT)
    {
        m.x += 0.1f;
    }
    setGL();
    DrawGL();
    CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

这些是通过键盘功能调用的功能。

void CView::setGL(GLvoid)           
{
    glClearColor(0.0f, 0.0f, 0.0f, 0.5f);       
    glClearDepth(1.0f); 
    glEnable(GL_DEPTH_TEST);    
    glDepthFunc(GL_LEQUAL);             
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    // light source configuration ##################
    glMatrixMode(GL_MODELVIEW);
    gluLookAt(0.f,0.f,1.f, 0.f,0.f,0.f, 0.f,1.f,0.f);

    GLfloat light0_diffuse[] = {0.5, 0.5, 1.0};
    GLfloat light0_specular[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat light0_spot_direction[] = {1,1,1,0};

    GLfloat light1_diffuse[] = {1.0f, 0.3f, 0.3f};
    GLfloat light1_specular[] = {1.0f, 0.8f, 0.8f, 1.0f};
    GLfloat light1_shiniess[] = {50.0};
    GLfloat light1_pos[] = {m.x, m.y, m.z};

    glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);
    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, light0_spot_direction);

    glLightfv(GL_LIGHT1, GL_DIFFUSE, light1_diffuse);
    glLightfv(GL_LIGHT1, GL_SPECULAR, light1_specular);
    glLightfv(GL_LIGHT1, GL_SHININESS, light1_shiniess);
    glLightfv(GL_LIGHT1, GL_POSITION, light1_pos);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_LIGHT1);
}

void CView::DrawGL(void)                
{
    // clear screen and depth buffer
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glLoadIdentity();
    // camera view configuration 
    gluLookAt(0.0f,0.0f,1.0f, 0.0f,0.0f,0.0f, 0.0f,1.0f,0.0f);

    // draw 
    //glColor3f(1.f, 1.f, 1.f);
    glPushMatrix();
    glTranslatef(m.x, m.y, m.z);
    glutSolidSphere(0.25f, 120, 120);

    glPopMatrix();
    glBegin(GL_TRIANGLES);
    glVertex3f(-0.5f, 0.5f, -0.5f);
    glVertex3f(0.0f, 0.0f, -0.5f);
    glVertex3f(-1.0f, 0.0f, -0.5f);

    m.calculateNormal(-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -0.5f, -1.0f, 0.0f, -0.5f);
    glNormal3f(m.normalX, m.normalY, m.normalZ);

    glBegin(GL_TRIANGLES);
    glVertex3f(0.5f, 0.5f, -1.0f);
    glVertex3f(0.0f, 0.0f, -1.0f);
    glVertex3f(1.0f, 0.0f, -1.0f);

    m.calculateNormal(0.5f, 0.5f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, -1.0f);
    glNormal3f(m.normalX, m.normalY, m.normalZ);

    glEnd();

    // swap buffer
    SwapBuffers(m_hDC);
}

Answer 1

您永远不应该在输入事件处理程序中放置绘图调用。那是你的主要问题。另一个问题是 - 似乎 - 你把OpenGL混淆为一个场景图。

OpenGL是一个绘图API，无论如何都不会回忆起场景。在输入处理程序中，您可以设置一些变量，发出重绘事件，然后在绘图事件处理程序中根据这些变量进行渲染。作为状态机绘图API的OpenGL也意味着没有明确的初始化阶段。像setGL这样的函数没有任何意义。你在setGL中所做的事实际上属于绘图功能。这包括设置视口和投影矩阵！

void CView::drawGL(GLvoid)           
{
    glClearColor(0.0f, 0.0f, 0.0f, 0.5f);       
    glClearDepth(1.0f); 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

    glViewport(…);
    glMatrixMode(GL_PROJECTION);
        set_projection_matrix(…);    

    // light source configuration ##################
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity(); // gluLookAt expects to work from a identity matrix.
    gluLookAt(0.f,0.f,1.f, 0.f,0.f,0.f, 0.f,1.f,0.f);

    GLfloat light0_diffuse[] = {0.5, 0.5, 1.0};
    GLfloat light0_specular[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat light0_spot_direction[] = {1,1,1,0};

    GLfloat light1_diffuse[] = {1.0f, 0.3f, 0.3f};
    GLfloat light1_specular[] = {1.0f, 0.8f, 0.8f, 1.0f};
    GLfloat light1_shiniess[] = {50.0};
    GLfloat light1_pos[] = {m.x, m.y, m.z};

    glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);
    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, light0_spot_direction);

    glLightfv(GL_LIGHT1, GL_DIFFUSE, light1_diffuse);
    glLightfv(GL_LIGHT1, GL_SPECULAR, light1_specular);
    glLightfv(GL_LIGHT1, GL_SHININESS, light1_shiniess);
    glLightfv(GL_LIGHT1, GL_POSITION, light1_pos);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_LIGHT1);

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);

    // draw 
    glColor3f(1.f, 1.f, 1.f);
    glPushMatrix();
    glTranslatef(m.x, m.y, m.z);
    glutSolidSphere(0.25f, 120, 120);
    glPopMatrix();

    glBegin(GL_TRIANGLES);
    glVertex3f(-0.5f, 0.5f, -0.5f);
    glVertex3f(0.0f, 0.0f, -0.5f);
    glVertex3f(-1.0f, 0.0f, -0.5f);

    m.calculateNormal(-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -0.5f, -1.0f, 0.0f, -0.5f);
    glNormal3f(m.normalX, m.normalY, m.normalZ);

    glBegin(GL_TRIANGLES);
    glVertex3f(0.5f, 0.5f, -1.0f);
    glVertex3f(0.0f, 0.0f, -1.0f);
    glVertex3f(1.0f, 0.0f, -1.0f);

    m.calculateNormal(0.5f, 0.5f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, -1.0f);
    glNormal3f(m.normalX, m.normalY, m.normalZ);
    glEnd();

    // swap buffer
    SwapBuffers(m_hDC);
}

对glLight…的调用发生在当前设置状态的上下文中（最重要的是灯光是模型视图矩阵）。光位置乘以模型视图矩阵。如果您使用gluLookAt，则glLightfv(GL_LIGHT<n>, GL_POSITION, …)的调用必须在gluLookAt之后和绘制照明几何体之前进行。

Answer 2

void CView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
    ...
    CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

这不是一个无限的递归调用？你的编译器不是在警告你吗？

如何记录光线位置的变化？

2 个答案: