new feature - slideOnCollide parameter for "abstractMesh.moveWithCollisions" (defaults to true) (BabylonJS#16580)

Optional slideOnCollide parameter added to
"abstractMesh.moveWithCollisions", and it's logic implemented

Author: jon-heard

packages/dev/core/src/Collisions/collider.ts

@@ -500,11 +500,20 @@ export class Collider {
     /**
      * @internal
      */
-    public _getResponse(pos: Vector3, vel: Vector3): void {
+    public _getResponse(pos: Vector3, vel: Vector3, slideOnCollide: boolean): void {
+        // Handle straight movement up to collision
+
         pos.addToRef(vel, this._destinationPoint);
         vel.scaleInPlace(this._nearestDistance / vel.length());
 
         this._basePoint.addToRef(vel, pos);
+
+        if (!slideOnCollide) {
+            return;
+        }
+
+        // Handle slide movement past collision
+
         pos.subtractToRef(this.intersectionPoint, this._slidePlaneNormal);
         this._slidePlaneNormal.normalize();
         this._slidePlaneNormal.scaleToRef(this._epsilon, this._displacementVector);

packages/dev/core/src/Collisions/collisionCoordinator.ts

@@ -15,7 +15,8 @@ export interface ICollisionCoordinator {
         maximumRetry: number,
         excludedMesh: Nullable<AbstractMesh>,
         onNewPosition: (collisionIndex: number, newPosition: Vector3, collidedMesh: Nullable<AbstractMesh>) => void,
-        collisionIndex: number
+        collisionIndex: number,
+        slideOnCollide?: boolean
     ): void;
     init(scene: Scene): void;
 }
@@ -36,15 +37,16 @@ export class DefaultCollisionCoordinator implements ICollisionCoordinator {
         maximumRetry: number,
         excludedMesh: AbstractMesh,
         onNewPosition: (collisionIndex: number, newPosition: Vector3, collidedMesh: Nullable<AbstractMesh>) => void,
-        collisionIndex: number
+        collisionIndex: number,
+        slideOnCollide: boolean = true
     ): void {
         position.divideToRef(collider._radius, this._scaledPosition);
         displacement.divideToRef(collider._radius, this._scaledVelocity);
         collider.collidedMesh = null;
         collider._retry = 0;
         collider._initialVelocity = this._scaledVelocity;
         collider._initialPosition = this._scaledPosition;
-        this._collideWithWorld(this._scaledPosition, this._scaledVelocity, collider, maximumRetry, this._finalPosition, excludedMesh);
+        this._collideWithWorld(this._scaledPosition, this._scaledVelocity, collider, maximumRetry, this._finalPosition, slideOnCollide, excludedMesh);
 
         this._finalPosition.multiplyInPlace(collider._radius);
         //run the callback
@@ -65,6 +67,7 @@ export class DefaultCollisionCoordinator implements ICollisionCoordinator {
         collider: Collider,
         maximumRetry: number,
         finalPosition: Vector3,
+        slideOnCollide: boolean,
         excludedMesh: Nullable<AbstractMesh> = null
     ): void {
         const closeDistance = AbstractEngine.CollisionsEpsilon * 10.0;
@@ -96,7 +99,11 @@ export class DefaultCollisionCoordinator implements ICollisionCoordinator {
         }
 
         if (velocity.x !== 0 || velocity.y !== 0 || velocity.z !== 0) {
-            collider._getResponse(position, velocity);
+            collider._getResponse(position, velocity, slideOnCollide);
+            // Halt all movement at the first collision, if not slideOnCollide
+            if (!slideOnCollide) {
+                velocity.setAll(0);
+            }
         }
 
         if (velocity.length() <= closeDistance) {
@@ -105,7 +112,7 @@ export class DefaultCollisionCoordinator implements ICollisionCoordinator {
         }
 
         collider._retry++;
-        this._collideWithWorld(position, velocity, collider, maximumRetry, finalPosition, excludedMesh);
+        this._collideWithWorld(position, velocity, collider, maximumRetry, finalPosition, slideOnCollide, excludedMesh);
     }
 }
 

packages/dev/core/src/Meshes/abstractMesh.ts

@@ -1929,9 +1929,10 @@ export abstract class AbstractMesh extends TransformNode implements IDisposable,
      * Move the mesh using collision engine
      * @see https://doc.babylonjs.com/features/featuresDeepDive/cameras/camera_collisions
      * @param displacement defines the requested displacement vector
+     * @param slideOnCollide If true, the mesh will slide along a collider's surface.  If false, it will stop moving at the first collision. (true by default)
      * @returns the current mesh
      */
-    public moveWithCollisions(displacement: Vector3): AbstractMesh {
+    public moveWithCollisions(displacement: Vector3, slideOnCollide: boolean = true): AbstractMesh {
         const globalPosition = this.getAbsolutePosition();
 
         globalPosition.addToRef(this.ellipsoidOffset, this._internalAbstractMeshDataInfo._meshCollisionData._oldPositionForCollisions);
@@ -1950,7 +1951,8 @@ export abstract class AbstractMesh extends TransformNode implements IDisposable,
             this.collisionRetryCount,
             this,
             this._onCollisionPositionChange,
-            this.uniqueId
+            this.uniqueId,
+            slideOnCollide
         );
         return this;
     }