# geom2struct

## Syntax

## Description

converts a cell array of collision geometries into a structure array.`meshStruct`

= geom2struct(`geom`

)

specifies identifiers for the specified collision geometries.`meshStruct`

= geom2struct(`geom`

,`id`

)

specifies local offsets as 3-D homogeneous transformation matrices to apply to the vertices
of corresponding geometries.`meshStruct`

= geom2struct(___,LocalOffsetPose=`poseOffset`

)

## Examples

### Add Meshes to Mesh TSDF Manager

Create two collision boxes and one collision sphere. The collision boxes represent a static environment and the sphere represents a dynamic obstacle with a pose that could change at any time.

```
box1 = collisionBox(0.5,1,0.1);
box2 = collisionBox(0.5,0.1,0.2,Pose=trvec2tform([0 -0.45 0.15]));
sph = collisionSphere(0.125,Pose=trvec2tform([-0.1 0.25 0.75]));
showCollisionArray({box1,box2,sph});
title("Static Environment and Dynamic Obstacle")
v = [110 10];
view(v);
```

Create a mesh TSDF manager with a resolution of 25 cells per meter.

tsdfs = meshtsdf(Resolution=25);

To improve the efficiency of signed distance field computation, combine meshes that represent the static environment.

staticMeshes = geom2struct({box1,box2}); staticEnv = staticMeshes(1); staticEnv.Pose = eye(4); staticEnv.Vertices = []; staticEnv.Faces = []; for i = 1:numel(staticMeshes) H = staticMeshes(i).Pose; V = staticMeshes(i).Vertices*H(1:3,1:3)'+ H(1:3,end)'; nVert = size(staticEnv.Vertices,1); staticEnv.Vertices = [staticEnv.Vertices; V]; staticEnv.Faces = [staticEnv.Faces; staticMeshes(i).Faces+nVert]; end staticEnv.ID = 1;

Add the static environment mesh to the TSDF manager.

addMesh(tsdfs,staticEnv);

Convert the sphere collision geometry into a structure for the mesh TSDF manager. Assign it an ID of 2 and add it to the mesh TSDF manager.

obstacleID = 2; dynamicObstacle = geom2struct(sph,obstacleID); addMesh(tsdfs,dynamicObstacle); show(tsdfs) view(v) axis equal title("Mesh TSDFs of Static Environment and Dynamic Obstacle")

Update the pose of the dynamic obstacle in the mesh TSDF manager by changing `Pose`

property of the object handle of the obstacle. Then use the `updatePose`

function to update the pose of the mesh in the TSDF manager.

dynamicObstacle.Pose = trvec2tform([0.2 0.25 0.2]); updatePose(tsdfs,dynamicObstacle)

ans = 1

show(tsdfs) view(v) axis equal title("Updated Dynamic Obstacle Pose")

## Input Arguments

`geom`

— Collision geometry objects

`collisionBox`

| `collisionCapsule`

| `collisionCylinder`

| `collisionMesh`

| `collisionSphere`

| *N*-element cell array of collision geometry objects

Collision geometry object, specified as collision geometry object or as an
*N*-element cell array of collision geometry objects.
*N* is the number of collision objects in the cell array. A collision
object must be one of these objects:

`id`

— Geometry structure ID

positive integer | *N*-element vector of positive integers

Geometry structure ID, specified as a positive integer or an
*N*-element vector of positive integers. *N* is the
number of collision objects in `geom`

.

If `id`

is a *N*-element vector of positive
integers, then each ID in `id`

must be unique.

If `id`

is not specified, then the ID of the structure is set to
`1:`

. For example,
*N*`geom2struct({geom1,geom2,geom3})`

creates three structures
corresponding to `geom1`

, `geom2`

, and
`geom3`

with IDs set to `1`

, `2`

,
and `3`

, respectively.

`poseOffset`

— Local pose offset

4-by-4 homogeneous transformation matrix | 4-by-4-by-*N* array of homogeneous transformation matrices | `se3`

object | *N*-element array of `se3`

objects

## Output Arguments

`meshStruct`

— Geometry mesh structure

structure | *N*-element structure array

Geometry mesh structure, returned as a structure or an *N*-element
structure array. *N* is the number of collision objects in
`geom`

.

Each structure contains these fields:

`ID`

— ID of the geometry structure stored as a positive integer. By default, the ID of each structure corresponds to the index of the structure in`meshStruct`

. For example, if`meshStruct`

contains five mesh structures, the first mesh structure at index 1 has an`ID`

of`1`

, and the last mesh structure at index 5 has an`ID`

of`5`

.`Vertices`

— Vertices of the geometry, stored as an*M*-by-3 matrix. Each row represents a vertex in the form*[x y z]*with respect to the reference frame defined by`Pose`

.*M*is the number of vertices needed to represent the convex hull of the mesh.`Faces`

— Faces of the geometry, stored as an*M*-by-3 matrix. Each row contains three indices corresponding to vertices in`Vertices`

that define a triangle faces of the geometry.*M*is the number of vertices in`Vertices`

.`Pose`

— Pose of the geometry as a 4-by-4 homogeneous transformation matrix specifying a transformation from the world frame to the frame in which the vertices are defined.

## Extended Capabilities

### C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

## Version History

**Introduced in R2024a**

## See Also

`meshtsdf`

| `collisionBox`

| `collisionCapsule`

| `collisionCylinder`

| `collisionMesh`

| `collisionSphere`

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