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The GridSliceResizerComponent is a versatile tool designed to maintain the proportions of specific areas of 3D meshes while allowing others to stretch during scaling. This component should replace the static mesh component, rather than being used in conjunction with it.

The concept of the GridSliceResizerComponent is similar to the popular 9-Slice-Scaling technique used in 2D graphics, which keeps the borders of sprites unstretched while the inner rectangle is stretched. In essence, the GridSliceResizerComponent is a 27-Slice-Scaler for 3D meshes.

The component operates by dividing the bounding box of a 3D mesh into 27 cuboids, as illustrated below. Not all cuboids are visible in this picture. Only the once that are front facing:

     +-----+-----------+-----+
    /_____/___________/_____/|
   /_____/___________/_____/||
  /     /           /     /|||
  +----+-----------+-----+ |||
  | A  |     B     |  C  |/|||
  +----+-----------+-----+ |||
  |    |           |     | |||
  | D  |     E     |  F  | |||
  |    |           |     |/||/
  +----+-----------+-----+ |/
  | G  |     H     |  I  | /
  +----+-----------+-----+

The scaling behaviour is as follows (assuming all other faces of the bounding box are divided as the front facing one):

Center Cuboid (E): Vertices within this cuboid stretch on two axes (Y, Z). Corner Cuboids (A, C, G, I): These cuboids do not stretch on any axis. Middle Cuboids (B, H): These cuboids stretch horizontally but not vertically. Middle Cuboids (D, F): These cuboids stretch vertically but not horizontally.

The slicing areas are defined by the SlicerPivotOffset and BorderXNegative, BorderXPositive, etc. These border values range from 0 to 1 and extend from the mesh's pivot (which may be offset by SlicerPivotOffset) to the maximum or minimum of the bounding box's axis. If all borders are set to 1, the mesh will stretch like a regular mesh during scaling. If set to 0, no stretching will occur. Typically, you'll want the pivot in the middle of the mesh and the borders set to around 0.8.

You can visualize the borders and pivot in the Actor editor preview using bDebugDrawPivot, bDebugDrawBorderX, etc.

This component is only compatible with static meshes that have CPU access enabled. Ensure you enable CPU access in the static mesh editor.

Fields

class UStaticMesh * Mesh[Get]

The static mesh to slice. Make sure to enable CPU access on it.

double BorderXNegative[Get]

Slice border for the negative X axis.

double BorderXPositive[Get]

Slice border for the positive X axis.

double BorderYNegative[Get]

Slice border for the negative Y axis.

double BorderYPositive[Get]

Slice border for the positive Y axis.

double BorderZNegative[Get]

Slice border for the negative Z axis.

double BorderZPositive[Get]

Slice border for the positive Z axis.

FVector SlicerPivotOffset[Get]

How much the meshes pivot should be offset when applying the slice borders.

uint8 ScaleCenterMode[Get]

This parameter determines whether the center part of the object should be scaled. If set to false, the center vertices will remain stationary. This is particularly useful when you want to maintain the proportions of certain geometrical features in the center part, such as a doorknob. By keeping the center vertices in place, you can avoid unwanted stretching effects, resulting in a more visually appealing outcome. However, it's important to note that for a convincing visual effect, the texture applied to the object should also not stretch. If you encounter issues with texture stretching, consider adding an additional loop cut. This can help maintain the texture's proportions and prevent it from distorting. In case the mesh gets scaled down and some of the center vertices fall outside of the scaled down center all vertices that are inside the center will be scaled down uniformly.

bool bGenerateCollision[Get]

Whether or not a collision mesh should be created for the static mesh.

Object Data for friend

class FMRUKGridSliceResizerSpec

Member Functions

void SliceMesh ( )

Slice the mesh. This gets automatically called whenever the scale of the owning Actor changes.

UMRUKGridSliceResizerComponent ( )

virtual void TickComponent

( float DeltaTime,

ELevelTick TickType,

FActorComponentTickFunction * ThisTickFunction )