Declaration

TXGradientSampler = class(TCustomCenterRadiusAngleLutGradientSampler)

Description

TXGradientSampler samples a 1D linear gradient projected along a vector defined by StartPoint and EndPoint.

Clamp	Mirror	Repeat

Mathematics & Algorithm

Given start point $P_1=(X_1,Y_1)$ and end point $P_2=(X_2,Y_2)$, direction vector $V=P_2-P_1$.

For any sampling point $P=(X,Y)$, linear parameter $u$ is the scalar projection onto $V$:

$$u=\frac{(P-P_1)\cdot V}{\parallel V{\parallel }^2}=\frac{(X-X_1)(X_2-X_1)+(Y-Y_1)(Y_2-Y_1)}{(X_2-X_1{)}^2+(Y_2-Y_1{)}^2}$$