我正在使用 libnoise 和 OpenGL 进行地形生成。我做了一个看起来有点复杂的正常生成算法:
list = glGenLists(1);
glNewList(list, GL_COMPILE);
glPushAttrib(GL_ENABLE_BIT);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glDisable(GL_TEXTURE_2D);
glPushMatrix();
int h = 256;
int w = 256;
float h1 = 0.0f;
float h2 = 0.0f;
float h3 = 0.0f;
float div = 7.0f;
float lPos[] = { 128, image.GetHeight() + 15.0f, 128, 1.0f };
for (int x = 1; x < h; x++)
{
glColor3ub(139, 69, 19);
glLightfv(GL_LIGHT0, GL_POSITION, lPos);
glBegin(GL_TRIANGLE_STRIP);
for (int z = 1; z < w; z++)
{
h1 = image.GetValue(x, z).red / 7.0f;
h2 = image.GetValue(x + 1, z).red / 7.0f;
Vector3 t1, t2, t3;
Vector3 v1, v2, v3, v4, v5, v6;
t1 = Vector3(x, h1, z);
t2 = Vector3(x - 1, image.GetValue(x - 1, z).red / div, z);
t3 = Vector3(x, image.GetValue(x, z - 1).red / div, z - 1);
v1 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1, image.GetValue(x + 1, z).red / div, z);
t3 = Vector3(x, image.GetValue(x, z + 1).red / div, z + 1);
v2 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1, image.GetValue(x + 1, z).red / div, z);
t3 = Vector3(x + 1, image.GetValue(x + 1, z - 1).red / div, z - 1);
v3 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1, image.GetValue(x + 1, z - 1).red / div, - 1);
t3 = Vector3(x , image.GetValue(x, z - 1).red / div, z - 1);
v4 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x - 1, image.GetValue(x - 1, z + 1).red / div, z + 1);
t3 = Vector3(x - 1, image.GetValue(x - 1, z).red / div, z);
v5 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x - 1, image.GetValue(x - 1, z + 1).red / div, z + 1);
t3 = Vector3(x, image.GetValue(x, z + 1).red / div, z + 1);
v6 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
Vector3 normal1 = Vector3::Normalize((v1 + v2 + v3 + v4 + v5 + v6) / 6);
glNormal3f(normal1.X, normal1.Y, normal1.Z);
glVertex3f(x, h1, z);
t1 = Vector3(x + 1, h2, z);
t2 = Vector3(x + 1 - 1, image.GetValue(x + 1 - 1, z).red / div, z);
t3 = Vector3(x + 1, image.GetValue(x + 1, z - 1).red / div, z - 1);
v1 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1 + 1, image.GetValue(x + 1 + 1, z).red / div, z);
t3 = Vector3(x + 1, image.GetValue(x + 1, z + 1).red / div, z + 1);
v2 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1 + 1, image.GetValue(x + 1 + 1, z).red / div, z);
t3 = Vector3(x + 1 + 1, image.GetValue(x + 1 + 1, z - 1).red / div, z - 1);
v3 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1 + 1, image.GetValue(x + 1 + 1, z - 1).red / div, -1);
t3 = Vector3(x + 1, image.GetValue(x + 1, z - 1).red / div, z - 1);
v4 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1 - 1, image.GetValue(x + 1 - 1, z + 1).red / div, z + 1);
t3 = Vector3(x + 1 - 1, image.GetValue(x + 1 - 1, z).red / div, z);
v5 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
t2 = Vector3(x + 1 - 1, image.GetValue(x + 1 - 1, z + 1).red / div, z + 1);
t3 = Vector3(x + 1, image.GetValue(x + 1, z + 1).red / div, z + 1);
v6 = Vector3::Normalize(Vector3::Cross(t3 - t1, t2 - t1));
normal1 = Vector3::Normalize((v1 + v2 + v3 + v4 + v5 + v6) / 6);
glNormal3f(normal1.X, normal1.Y, normal1.Z);
glVertex3f(x + 1, h2, z);
}
glEnd();
}
glPopMatrix();
glPopAttrib();
glEndList();
所以,正如你所看到的,我正在生成法线,通过对周围六个面的法线进行平均,从而实现平滑的着色。问题是在某些地方(尤其是地形的较低部分),钻头仍然是黑色的,有奇怪的阴影。这是一张照片:
我的正常一代如何工作:
笔记!!!!我画了Y,我的意思是Z,对不起!
这是一张图片:
绿色是第一个顶点。
红色是第二个顶点(x 轴上的第一个 + 1)
黄色是相邻三角形的点。
X 是外环。
Z 是内环。
由于我使用的是GL_TRIANGLE_STRIP
,所以下一次迭代只需要 2 个顶点来构造一个三角形。
所以...构造每个三角形:
p1 = (x, image height, z)
p2 = (x + 1, image height, z)
并在下一次迭代(z++)
p3 = (x, 图像高度, z + 1)
p4 = (x + 1, 图像高度, z + 1)
...ETC。