照明行为不佳(固定管道)

时间:2014-03-27 15:25:11

标签: opengl lighting normals

我试图用OpenGL 1.1渲染一个对象(比如说立方体)(我知道现在没有意义,但我还是要使用它)。一切正常,直到我尝试一些照明。

问题在于:

Screenshot

全局变量集是:

static GLfloat light_position[] = {1.0, 1.0, 2*cZ.x , 0.0};   
// cZ.x is the minimum z of the mesh.  I know 
// this is at infinity, but don't work also with w=1.0

在主要功能中:

...
    glMatrixMode(GL_MODELVIEW);     // Select The Modelview Matrix
    glLoadIdentity();               // Reset The Modelview Matrix
    glEnable(GL_LIGHT0);
    glEnable(GL_LIGHTING);
    glShadeModel(GL_SMOOTH);        // Enable Smooth Shading

....

绘制网格k

//绘制网格物体k

        GLfloat light_ambient[] = {COLOUR[k][0], COLOUR[k][1], COLOUR[k][2], 1.0}; 
        GLfloat light_diffuse[] = {COLOUR[k][0], COLOUR[k][1], COLOUR[k][2], 1.0};  
        glLightfv(GL_LIGHT0, GL_POSITION, light_position);
                glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
        glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);


....
        //This is a mesh, so will be drawn using triangles
        glBegin(GL_TRIANGLES);
        //Triangles will be defined by vertex indices in faces
        for (unsigned int i = 0; i<mesh->faces.size(); i++){

            int index1 = mesh->faces.at(i).x;
            int index2 = mesh->faces.at(i).y;
            int index3 = mesh->faces.at(i).z;
            glNormal3f(mesh->normals.at(i).x,mesh->normals.at(i).y,mesh->normals.at(i).z);
            glVertex3f(mesh->vertices.at(index1).x, mesh->vertices.at(index1).y, mesh->vertices.at(index1).z);
            glVertex3f(mesh->vertices.at(index2).x, mesh->vertices.at(index2).y, mesh->vertices.at(index2).z);
            glVertex3f(mesh->vertices.at(index3).x, mesh->vertices.at(index3).y, mesh->vertices.at(index3).z);
        }
        glEnd();

....

而法线计算如下:

    glm::vec3 currFace = m->faces.at(faceIndex);
    glm::vec3 vert1 = m->vertices.at(currFace.x);
    glm::vec3 vert2 = m->vertices.at(currFace.y);
    glm::vec3 vert3 = m->vertices.at(currFace.z);

    glm::vec3 side1 = (vert2 - vert1);
    glm::vec3 side2 = (vert3 - vert1);

    glm::vec3 normal = glm::cross(side1, side2);

    normal = glm::normalize(normal);

我真的很难理解什么是错的,你能指出我正确的方向吗?

编辑:这种情况与斯坦福兔子一样(取自斯坦福回购,因此它很好地形成)

http://imgur.com/Z6225QG

1 个答案:

答案 0 :(得分:1)

看着你的法线图片看起来不仅没有被遮挡,你的一些物体面也是透明的。

我在学习OpenGL时遇到过类似的问题,在我的情况下,我忘了启用DEPTH_TEST。您只需将此行添加到GL初始化函数函数即可:

 glEnable(GL_DEPTH_TEST);

试一试