D3DXTRANSITION_TYPE
Microsoft DirectX 9.0 SDK Update (October 2004)

D3DXTRANSITION_TYPE Enumerated Type


Defines the transition style between values of a mesh animation.

Syntax

typedef enum _D3DXTRANSITION_TYPE {
    D3DXTRANSITION_LINEAR = 0x000,
    D3DXTRANSITION_EASEINEASEOUT = 0x001,
    D3DXEDT_FORCE_DWORD = 0x7fffffff
} D3DXTRANSITION_TYPE;

Constants

D3DXTRANSITION_LINEAR

Linear transition between values.

D3DXTRANSITION_EASEINEASEOUT

Ease-in, ease-out spline transition between values.

D3DXEDT_FORCE_DWORD

Forces this enumeration to compile to 32 bits in size. This value is not used.

Remarks

The calculation for the ramp from ease in to ease out is calculated as follows:

Q(t) = 2(x - y)t3 + 3(y - x)t2 + x.

where the ramp is a function Q(t) with the following properties:

Mathematically, this translates into:

Q(t) = At3 + Bt2 + Ct + D (and therefore, Q'(t) = 3At2 + 2Bt + C) 
2a) Q(0) = x 
2b) Q(1) = y

3a) Q'(0) = 0 
3b) Q'(1) = 0

Solving for A, B, C, D:

D = x   (from 2a)
C = 0  (from 3a)
3A + 2B = 0 (from 3b)
A + B = y - x (from 2b and D = x)

Therefore:

A = 2(x - y), B = 3(y - x), C = 0, D = x.

Enumerated Type Information

Headerd3dx9anim.h
Minimum operating systems Windows 98


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