Maths (Geometry): tanHalfAngle

       Name: tanHalfAngle                                            [Show more]
       Type: Variable
   Category: Maths (Geometry)
    Summary: Table for hypotenuse lengths given the tangent of an angle
    Context: See this variable in context in the source code
 References: This variable is used as follows:
             * GetHypotenuse uses tanHalfAngle


 Given the tangent of an angle, X = tan(theta), this table contains the
 following at index X:

   tanHalfAngle,X = 2 * tan(theta / 2)

 The table contains lookup values for indexes 0 to 128, which correspond to
 theta angles of 0 to 45 degrees.

 This allows us to approximate the length of the hypotenuse of a triangle with
 angle theta, adjacent side a and opposite side b, as follows:

   h =~ a + b * tan(theta / 2)


.tanHalfAngle

 EQUB 0

 FOR I%, 1, 128

  EQUB INT(0.5 + 2 * 256 * TAN(ATN(I% / 128) / 2))

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