D3DXFRESNELTERM function
Calculate the Fresnel coefficient.
definition:
FLOAT WINAPI D3DXFRESNELTERM
Float costa,
Float RefractionIndex
);
parameter:
Costheta
[in] This value must be between 0 and 1.
RefractionIndex
The Refraction Index of a Material. The Value Must Be Greater Than 1.
return value:
This function returns the number of non-polarized Fresnel. Costheta is the COS value of the incident angle.
Description:
Hereinafter, how to calculate the non-polarized Fresnel Cogens (f):
If A is an incident angle, B is a refraction angle, then calculates with the following formula.
F = 0.5 * [TAN2 (A - B) / TAN2 (A B) SIN2 (A - B) / SIN2 (A B)]
= 0.5 * sin2 (a - b) / sin2 (A B) * [COS2 (A B) / COS2 (A - B) 1]
Let R = Sina (a) / sin (b) (refractive factor)
Let C = Cos (a)
Let G = (R2 C2 - 1) 1/2
Then make the following formula after simplifying operations:
F = 0.5 * (G C) 2 / (g - c) 2 * ([C (G C) - 1] 2 / [C (G - C) 1] 2 1)
Function information:
HEADER
D3DX9Math.h
Import Library
D3DX9.LIB
Minimum operation systems
WINDOWS 98
