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Overview

NavMesh Queries provide an easy way to query for NavMesh triangles within an Axis Aligned Bounding Box (AABB), inside a NavMesh. These Queries are an essential part of the AI system and, among other things, may be used to obtain the NavMesh triangle ID of a specific location, the borders of a NavMesh around an agent, and so forth.

The system is powerful since it supports custom C++ filters and post-processing structures, and, as we'll see later on in this page, allows the user to filter out 'invalid' triangles from NavMeshes and perform post-processing transformations on them. 

Refer to Navigation Areas_ in the CRYENGINE V Manual for information on creating NavMeshes.

The two types of NavMesh Queries available are Instant Queries and Batch Queries. The following documentation describes their configuration, usage and debugging.

The following parameters are common to both Instant and Batch Queries.

ParameterDescription
Configuration

The following configuration parameters are required to specify how the NavMesh Query must be performed. 

MeshIDThe ID of the NavMesh on which the Query must run.
Caller (Optional)Identifies the AI agent performing the NavMesh Query. This identifier can be a user-defined name, and is used for debugging purposes.
AABBThe coordinates of the Query's Axis Aligned Bounding Box.
Overlapping Mode

Defines the criteria according to which the overlap between a NavMesh triangle and the Query's AABB is calculated. This parameter must have one of the following values:

BoundingBox_PartialChecks if there's an overlap between the AABB of the NavMesh triangle and the AABB of the Query.
BoundingBox_FullChecks if the AABB of the NavMesh triangle is fully inside the AABB of the Query.
Triangle_PartialChecks if there's an overlap between the NavMesh triangle and the AABB of the Query.
Triangle_FullChecks if the triangle is fully contained inside the AABB of the Query.
Query Filter

Contains additional logic to filter out triangles that satisfy the criteria specified by the Overlapping Mode parameter. This is useful to determine which triangles are to be passed as input to the NavMesh's post-processing logic.

The C++ class SAcceptAllQueryTrianglesFilter is the default filter, which accepts all triangles.

Processing SizeThe size of the batch in which triangles should be post-processed. The default value is 1024, which means the post–processing function is applied on every 1024 triangles returned by the running Query. 
Query Processing

Holds the triangle post-processing logic of the NavMesh Query.

The Query Processing logic works as a queue, such that the queue is filled with triangles that require processing while the Query is running. As soon as this queue reaches the size specified by the Processing Size parameter, the triangles are processed and the queue is emptied. How the triangles are processed depends on the specific implementation of the Query Processing logic.

For example, the default processing logic (MNM: CDefaultProcessing in C++) simply stores the IDs of the triangles returned by the NavMesh Query within an array, which is then accessed by the user.


Result

Describes the execution status of the NavMesh Query. It can have the following values:

UninitializedThe Query is not yet initialized.
RunningThe Query is running currently.
Done_QueryProcessingStoppedProcessing of the Query was stopped by the Query Processing logic, after the desired result was obtained.
Done_Complete

All triangles were successfully processed, and the Query was completed.

The difference between Done_QueryProcessingStopped and Done_Complete is that in the case of the former, the Query is stopped when the Query Processing logic decides. Whereas in the case of Done_Complete, the Query stops when it has processed all triangles inside its AABB.
Invalid_InitializationFailedThe Query failed to initialize.
Invalid_NavMeshRegeneratedProcessing of the Query ended because of a NavMesh regeneration.
Invalid_NavmeshAnnotationChangedProcessing of the Query ended because of a change in a NavMesh's annotation.
Invalid_CachedNavMeshIdNotFoundProcessing of the Query failed because the internal ID of the NavMesh was no longer valid after a regeneration.

Returns the complete result when executed. Because of this, Instant Queries don't maintain an internal state and are particularly useful when it is known that the running time of the Query will be short, or when developers cannot afford to wait for the next frame for the Query's result.

How to create an InstantNavMeshQuery
// Create the Query config. Note that it is of type SNavMeshQueryConfigInstant.
const MNM::INavMeshQuery::SNavMeshQueryConfigInstant config(...);
 
// Create the Query Processing parameter.
MNM::CDefaultProcessing defaultProcessing(1024);
 
// Call the QueryManager to run an instant query, passing the Query Configuration and the Query Processing parameter.
MNM::INavMeshQuery::EQueryStatus queryStatus = gEnv->pAISystem->GetNavigationSystem()->GetNavMeshQueryManager()->RunInstantQuery(config, defaultProcessing);
 
// Check if the Query ran successfully.
if (queryStatus == MNM::INavMeshQuery::EQueryStatus::Done_Complete)
{
	// Access the IDs of the resultant triangles stored in the Query Processing queue.
	DoSomethingWithTheResult(defaultProcessing.GetTriangleIdArray()); 
}

Returns only a batch/part of the complete result when executed; the next batch of results is returned when the Query is executed again, until the complete result has been returned.

Because of this, Batch Queries maintain an internal state to keep track of where execution should next begin from, and are useful when computing must be split across multiple frames for performance.

Batch Queries require the following additional parameters in their configuration:

ParameterDescription
Processing Triangles Max Size 

The maximum number of triangles that can be processed by the Query in total.

This parameter is not to be confused with the Processing Size parameter described in the Common Parameters section above. Processing Triangles Max Size must be equal to or bigger than Processing Size.

Action on NavMesh Regeneration

Defines how the Query should react when the queried NavMesh is being regenerated. This parameter can take one of the following values:

IgnoreChanges in the NavMesh are ignored and execution of the Query continues, unless a change in the NavMesh occurs within the same NavMesh tile that the Query is processing.
Invalidate AlwaysThe NavMesh Query is immediately invalidated and it's execution is stopped when the NavMesh changes.
Invalidate if ProcessedThe Query is invalidated and its execution is stopped only when a NavMesh regeneration affects a NavMesh tile that has already been processed by the Query.
Action on NavMesh Annotation Change

Defines how the Query should react when the queried NavMesh's annotation changes. This parameter can take the following values:

IgnoreChanges in the NavMesh are ignored and triangles continue to be processed, unless a change in the NavMesh's annotation occurs within the same tile that the Query is processing.
Invalidate AlwaysThe NavMesh Query is immediately invalidated and it's processing is stopped when the NavMesh's annotation changes.
Invalidate if ProcessedThe Query is invalidated and its execution is stopped only when the change in a NavMesh's annotation occurs within a tile that has already been processed by the Query.
How to create a BatchNavMeshQuery
// Create the Query config. Note that it is of the type SNavMeshQueryConfigBatch.
const MNM::INavMeshQuery::SNavMeshQueryConfigBatch config(...);
 
// Create the Query Processing. The size of the defaultProcessing should be smaller or equal to the size of the batches (performance reasons).
MNM::CDefaultProcessing defaultProcessing(batchSize)
 
// Call the QueryManager to create a Batch Query. As opposed to Instant Queries, we're not running the Batch Query directly here but are being returned a pointer instead that we will use to execute the Query when we need to.
MNM::INavMeshQueryPtr * pQuery = gEnv->pAISystem->GetNavigationSystem()->GetNavMeshQueryManager()->CreateBatchQuery(config);
 
// Imagine that we want to run the Query while we still have some time left in this frame.
// This will execute the query in batches of batchSize until the Query is done, fails or we run out of time.
while(pQuery->IsValid() && !pQuery->IsDone() && timeLeftInThisFrame)
{
	// Run a single Query batch of the specified size.
	pQuery->Run(defaultProcessing, batchSize);
 
	// Access the result stored in Query Processing.
	DoSomethingWithTheResult(defaultProcessing.GetTriangleIdArray());
 
	// Update time left in this frame.
	UpdateTimeLeftInFrame();
}
 

The following CVars can be used for debugging NavMesh Queries.

NameVariableDefaultDescriptionFlags

ai_storeNavigationQueriesHistory

StoreNavigationQueriesHistory

0

When enabled, a history of NavMesh Queries is maintained. This history can be displayed by enabling the ai_DebugDrawNavigationQueriesUDR or ai_DebugDrawNavigationQueriesList CVars.

Requires CVars ai_debugDraw and ai_debugDrawNavigation to be enabled.

VF_CHEAT | VF_CHEAT_NOCHECK

ai_DebugDrawNavigationQueriesUDR

DebugDrawNavigationQueriesUDR

0

Displays the debug information (config, triangles and invalidations) of NavMesh Queries using UDR.

Requires ai_debugDraw, ai_debugDrawNavigation and ai_storeNavigationQueriesHistory to be enabled.

VF_CHEAT | VF_CHEAT_NOCHECK

ai_DebugDrawNavigationQueriesList

DebugDrawNavigationQueriesList

0

Displays a list of NavMesh Queries, with all batches and elapsed times.

Requires ai_debugDraw, ai_debugDrawNavigation and ai_storeNavigationQueriesHistory to be enabled. Note that, by their nature, instant queries won't be listed here.

VF_CHEAT | VF_CHEAT_NOCHECK

ai_DebugDrawNavigationQueryListFilterByCaller

DebugDrawNavigationQueryListFilterByCallerNone

Displays a list of NavMesh Queries, containing only those queries that contain the given filter string.

By default, its value is set to None (no filter is applied).

Requires ai_debugDraw, ai_debugDrawNavigation and ai_DebugDrawNavigationQueriesList to be enabled.




There are two debug modes available:

In List mode (enabled by the ai_DebugDrawNavigationQueriesList CVar), all running NavMesh Queries are displayed in a list in real time. This is very useful to see when a query is being executed, and the number of frames it lasts for. Using the ai_DebugDrawNavigationQueryListFilterByCaller CVar, we can only display calls from a specific caller.

Since InstantQueries only run for a single frame, they won't show up in List debugging mode.


List mode when debugging NavMesh Queries. Shows one query with 5 batches of 3 triangles each

The results of all NavMesh Queries can also be visualized in the UDR Visualizer. The ai_DebugDrawNavigationQueriesUDR CVar has to be enabled for this.

Hierarchy of different Queries and all other information Results of Query 13. Bounding box and Triangles are drawnStatistics child expanded

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