math - glsl中光的半向量是什么？

Question

我正在使用每像素照明着色器，但我不知道一件事:什么是光源的半向量？

vec3 halfVector = normalize(gl_LightSource[1].halfVector.xyz);

我希望你能用数学行来解释它，我比文字更懂数学:)

Answer 1

来自 this post :

A "halfway vector" (if you mean that by "half vector") is the unit vector at the half angle between two other vectors. Normally the halfway vector [...] is computed between the vector to the viewer v and the light source l:

h := ( v + l ) / || v + l ||

因此，半向量是单位 angle bisector View 和光矢量。

编辑:有关包括半矢量在内的照明模型的完整说明，请参阅 Blinn-Phong wikipedia article