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johnnyBravo

With D3DCULL whats difference of using Cull back clockwise/counterClockwise vertices?

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Hi, I''m just curious with culling whats the difference between using the D3DCULL_CW(clockwise) and D3DCULL_CCW(counter clockwise)? Im using clockwise so far, but i cant see why we need the option of two ways of culling. Why is that? Thankyou

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with clockwise, vertices that wind clockwise around a triangle are culled, the reverse for counterclockwise. so, if you have a triangle on the screen that looks like:



1+
/ \
/ \
/ \
/ \
2+---------+3

this would be culled by D3DCULL_CCW, because the vertices go counterclockwise. if any two vertices were swapped, it would be culled by D3DCULL_CW

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That would be the correct definition. But to better understand it, D3DCULL_CCW culls all the faces turning away from the user, whereas D3DCULL_CW culls all the faces turning towards the user.

If you use D3DCULL_CCW, you''ll see the "outer" surfaces of objects, since only the back-facing polygons are culled. But if you turn on D3DCULL_CW, you''ll see only the back faces, or the polygons on the "inside" of your model.

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