change(/wiki/backface-culling): some notes and links

content/wiki/backface-culling/index.md

@@ -7,3 +7,25 @@ tags = ["rendering", "culling", "optimization"]
 +++
 
 {{ stub_notice() }}
+
+**Notes:**
+
+- Faces have a *winding order*:
+  - Clockwise
+  - Counter-Clockwise
+- Faces have a *surface normal*.
+- Cameras have a *view direction*.
+- The dot-product of a surface-normal and view-direction indicates
+  if a face is facing the camera, or not.
+- GPU rasterizers have built-in back-face culling.
+- Vertices (and thus faces) can be *discarded*,
+  by setting them to `NaN` in the vertex shader.
+
+## References
+
+- [Wikipedia: Back-Face Culling](https://en.wikipedia.org/wiki/Back-face_culling)
+- [OpenGL Wiki: (Back)Face Culling](https://www.khronos.org/opengl/wiki/Face_Culling)
+- [LearnOpenGL: (Back)Face Culling](https://learnopengl.com/Advanced-OpenGL/Face-culling)
+- [Fine-grained Backface Culling by *zeux*](https://zeux.io/2023/04/28/triangle-backface-culling/)
+- [Back Face Culling by *jonshiach*](https://jonshiach.github.io/graphics-book/files/4.3_Backface_culling.html)
+- [Back Face Culling by *karan*](https://www.dgp.toronto.edu/~karan/courses/csc418/fall_2002/notes/cull.html)