FBrushMaskDab

One dab's sampler state, prepared once per dab by PrepareBrushMaskDab and read per post.

Declaration

struct FBrushMaskDab

Header: #include "Native/BrushMask.h"
Module: PublicDependencyModuleNames.Add("OrreryTerrainCore"); in your module’s Build.cs.
Stability: Experimental: supported, may change in a minor version, with a changelog line.

Description

A post's offset from the brush centre (mm) becomes the mask's local position in Q16 millimetres (Local), then M (SampleBrushMask). Every step is integer, and a post's value depends on its offset alone, never on the window or the order the posts are visited in.

Functions

Local
The mask's local position of a post at offset (Dx_mm, Dy_mm) from the brush centre: rotated by -MaskAngle, mirrored when asked, in Q16 millimetres (floored).
SquareT_q16
The square footprint's normalised distance in Q16: max(|X| / HalfX, |Y| / HalfY), at most 65536, with no root.

Properties

Name	Type	Default	Meaning
`Mask`	`const FBrushMask*`	`nullptr`	—
`Texels`	`const uint16_t*`	`nullptr`	The sampled level's u.
`Side`	`int32_t`	`0`	Samples per side of the sampled level.
`Level`	`uint32_t`	`0`	—
`Cos_q30`	`int64_t`	`int64_t(1) << 30`	—
`Sin_q30`	`int64_t`	`0`	—
`bMirror`	`bool`	`false`	—
`bBicubic`	`bool`	`false`	kBrushMaskBicubic: sampled by the Catmull-Rom cubic instead of bilinearly (SampleBrushMask).
`HalfX_mm`	`int64_t`	`0`	The mask's half-sides on the ground (BrushMaskHalfSides): the aspect ratio scales the mask before the rotation.
`HalfY_mm`	`int64_t`	`0`	—
`HalfX_q16`	`int64_t`	`0`	—
`HalfY_q16`	`int64_t`	`0`	—
`Tol_q16`	`int64_t`	`0`	How far outside the half-sides a position still counts as inside: covers the CORDIC's error.
`ScaleX`	`int64_t`	`0`	Level samples per Q16 mm along local X, << kBrushMaskScaleShift.
`ScaleY`	`int64_t`	`0`	—
`InvHalfX`	`int64_t`	`0`	2^kBrushMaskInvShift / HalfX_mm, rounded.
`InvHalfY`	`int64_t`	`0`	—