Back face culling

[Dipucian]

Sorry for a stupid question... actually how does it determine which face is "back"?



I have 3 vertex:

v0: (0, 1, 2)

v1: (0, 0, 2)
v2: (1, 0, 2)

​

which form a simple right-angled triangle.



and I have the camera:

position: (0, 0, -5)

lookAt: (0, 0, 0)
Up: (0, 1, 0)

​

when I use the default culling mode (counterClockwise), I cant see the triangle...

But when I turn it off or use the Clockwise mode, I clearly see that, with differently colored vertex, my triangle vertex are counterClockwise... (v0 on top, v1 left and v2 right)

Im mad with this, anyone got the same question? I really cant understand this...

 

[PlausiblyDamp]

http://www.pluralsight.com/craig/articleview.aspx/DirectX/Direct3D/05 Rendering VertexBuffer.xml is worth a read, explains culling towards the end.

 

[Dipucian]

Thanks for the quick help!!

So, setting cull mode to CounterClockwise means that triangles with counterclockwise vertex are backward facing and will not be drawn...