GL_QUAD_STRIP 上的 OpenGL 光照和着色

发布于 2024-12-08 15:07:21 字数 803 浏览 0 评论 0原文

OpenGL新手，尝试实现带有阴影和照明的球体。我知道有一个我可以调用的球体函数，但尝试创建我自己的球体函数。但是，虽然我可以在场景中的其他对象（例如 glcubes 等）上获得照明和阴影，但我无法在球体上获得任何阴影或照明。任何建议将不胜感激！

波纹管是我绘制球体的函数：

void cg_SolidSphere( GLint slices, GLint stacks )
{
    float x, y, z ;
    for( float lat = 0 ; lat < PI ; lat = lat + PI/stacks )
    {
        glBegin( GL_QUAD_STRIP ) ;
        for( float lon = 0 ; lon < 2*PI ; lon = lon + 2*PI/slices )
        {
            x = cosf( lat ) * sinf( lon ) ;
            y = sinf( lat ) * sinf( lon ) ;
            z = cosf( lon ) ;
            glVertex3f( x, y, z ) ;
            x = cosf( lat + PI/stacks ) * sinf( lon ) ;
            y = sinf( lat + PI/stacks ) * sinf( lon ) ;
            z = cosf( lon ) ;
            glVertex3f( x, y, z ) ;
        }
        glEnd() ;
    }
}

原文

New to OpenGL, trying to implement a sphere with shading and lighting. I am aware that there is a sphere function I could call on, but trying to create my own. However, while I can get lighting and shading on other objects in the scene (such as glcubes, etc.), I am unable to get any shading or lighting on the sphere. Any suggestions would be greatly appreciated!

Bellow is my function to draw the sphere:

void cg_SolidSphere( GLint slices, GLint stacks )
{
    float x, y, z ;
    for( float lat = 0 ; lat < PI ; lat = lat + PI/stacks )
    {
        glBegin( GL_QUAD_STRIP ) ;
        for( float lon = 0 ; lon < 2*PI ; lon = lon + 2*PI/slices )
        {
            x = cosf( lat ) * sinf( lon ) ;
            y = sinf( lat ) * sinf( lon ) ;
            z = cosf( lon ) ;
            glVertex3f( x, y, z ) ;
            x = cosf( lat + PI/stacks ) * sinf( lon ) ;
            y = sinf( lat + PI/stacks ) * sinf( lon ) ;
            z = cosf( lon ) ;
            glVertex3f( x, y, z ) ;
        }
        glEnd() ;
    }
}

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‘画卷フ 2024-12-15 15:07:21

您还需要调用 glNormal3f 。在这种情况下，法线与顶点相同，因此我们可以使用相同的点：

x = cosf( lat ) * sinf( lon ) ;
y = sinf( lat ) * sinf( lon ) ;
z = cosf( lon ) ;
glNormal3f( x, y, z ) ;
glVertex3f( x, y, z ) ;
x = cosf( lat + PI/stacks ) * sinf( lon ) ;
y = sinf( lat + PI/stacks ) * sinf( lon ) ;
z = cosf( lon ) ;
glNormal3f( x, y, z ) ;
glVertex3f( x, y, z ) ;

You need glNormal3f calls, too. In this case, the normal is the same as the vertex, so we can use the same points:

x = cosf( lat ) * sinf( lon ) ;
y = sinf( lat ) * sinf( lon ) ;
z = cosf( lon ) ;
glNormal3f( x, y, z ) ;
glVertex3f( x, y, z ) ;
x = cosf( lat + PI/stacks ) * sinf( lon ) ;
y = sinf( lat + PI/stacks ) * sinf( lon ) ;
z = cosf( lon ) ;
glNormal3f( x, y, z ) ;
glVertex3f( x, y, z ) ;

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