OK, given that the cosine(45 degrees) is .7071, and that the light color is 1 light intensity is 1, material Diffuse_Color = 1, and Diffuse_Value = 1, the formula tells us that

1 * 1 * .7071 * 1 * 1 = .7071

So the rightmost rectangle should be showing .7071 * 255 = 180.

Go measure it.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)