HARP-12773: Roadshield icon disappear, while text remains visible

* also fixes infinite render loop due to only part of road shields rendered

Signed-off-by: stefan.dachwitz <[email protected]>

@here/harp-mapview/lib/text/Placement.ts

@@ -46,7 +46,7 @@ const tmpPointDir = new THREE.Vector3(0, 0, 0);
 const COS_TEXT_ELEMENT_FALLOFF_ANGLE = 0.5877852522924731; // Math.cos(0.3 * Math.PI)
 
 /**
- * Checks whether the distance of the text element to the camera plane meets threshold criterias.
+ * Checks whether the distance of the text element to the camera plane meets threshold criteria.
  *
  * @param textElement - The textElement of which the view distance will be checked, with coordinates
  * in world space.
@@ -86,7 +86,7 @@ function checkViewDistance(
  * Computes distance of the specified text element to camera plane given with position and normal.
  *
  * The distance is measured as projection of the vector between `eyePosition` and text
- * eonto the `eyeLookAt` vector, so it actually computes the distance to plane that
+ * onto the `eyeLookAt` vector, so it actually computes the distance to plane that
  * contains `eyePosition` and is described with `eyeLookAt` as normal.
  *
  * @note Used for measuring the distances to camera, results in the metric that describes
@@ -411,9 +411,6 @@ export function placeIcon(
  * @param env - The {@link @here/harp-datasource-protocol#Env} used
  *              to evaluate technique attributes.
  * @param screenCollisions - Used to check collisions with other labels.
- * @param isRejected - Whether the label is already rejected (e.g. because its icon was rejected).
- * If `true`, text won't be checked for collision, result will be either `PlacementResult.Invisible`
- * for newly placed (upcoming) label or `PlacementResult.Rejected` if the label was persistent.
  * @param outScreenPosition - The final label screen position after applying any offsets.
  * @param multiAnchor - The parameter decides if multi-anchor placement algorithm should be
  * used, be default [[false]] meaning try to place label using current alignment settings only.
@@ -583,9 +580,6 @@ function placePointLabelChoosingAnchor(
  * @param env - The {@link @here/harp-datasource-protocol#Env}
  *              used to evaluate technique attributes.
  * @param screenCollisions - Used to check collisions with other labels.
- * @param isRejected - Whether the label is already rejected (e.g. because its icon was rejected).
- * If `true`, text won't be checked for collision, result will be either `PlacementResult.Invisible`
- * or `PlacementResult.Rejected`.
  * @param outScreenPosition - The final label screen position after applying any offsets.
  * @returns `PlacementResult.Ok` if point label can be placed, `PlacementResult.Rejected` if there's
  * a collision, `PlacementResult.Invisible` if it's not visible.
@@ -632,9 +626,6 @@ function placePointLabelAtCurrentAnchor(
  * @param env - The {@link @here/harp-datasource-protocol#Env}
  *              used to evaluate technique attributes.
  * @param screenCollisions - Used to check collisions with other labels.
- * @param isRejected - Whether the label is already rejected (e.g. because its icon was rejected).
- * If `true`, text won't be checked for collision, result will be either `PlacementResult.Invisible`
- * or `PlacementResult.Rejected`.
  * @param forceInvalidation - Set to true if text layout or other params has changed such as text
  * re-measurement is required and text buffer need to be invalidated.
  * @param outScreenPosition - The final label screen position after applying any offsets.

@here/harp-mapview/lib/text/TextElementsRenderer.ts

@@ -1574,6 +1574,7 @@ export class TextElementsRenderer {
     ): boolean {
         const pointLabel: TextElement = labelState.element;
         const textRenderState: RenderState | undefined = labelState.textRenderState;
+        const isLineMarker = iconIndex !== undefined;
 
         assert(iconIndex === undefined || labelState.iconRenderStates !== undefined);
         const iconRenderState: RenderState =
@@ -1681,16 +1682,24 @@ export class TextElementsRenderer {
                     placementStats.numPoiTextsInvisible++;
                 }
                 if (!renderIcon || iconInvisible) {
-                    labelState.reset();
+                    // Reset only the iconRenderState for line markers, not the shared
+                    // textRenderState, since some icons may be invisible while others are visible.
+                    // The labelState has to be reset by the calling function if no icons are
+                    // placed to reset the textRenderState properly.
+                    if (isLineMarker) {
+                        iconRenderState.reset();
+                    } else {
+                        labelState.reset();
+                    }
                     return false;
                 }
                 textRenderState!.reset();
             }
 
-            const iconIsRequired = !(poiInfo?.iconIsOptional === false);
-            // Rejected icons are only considered to hide the text if they are valid, so a missing icon image will
-            // not keep the text from showing up.
-            const requiredIconRejected: boolean = iconRejected && iconReady && iconIsRequired;
+            const iconIsOptional = poiInfo?.iconIsOptional !== false;
+            // Rejected icons are only considered to hide the text if they are valid, so a missing
+            // icon image will not keep the text from showing up.
+            const requiredIconRejected: boolean = iconRejected && iconReady && !iconIsOptional;
 
             const textRejected = requiredIconRejected || placeResult === PlacementResult.Rejected;
             if (!iconRejected && !iconInvisible) {
@@ -1831,6 +1840,7 @@ export class TextElementsRenderer {
 
         // Process markers (with shield groups).
         if (minDistanceSqr > 0 && shieldGroup !== undefined) {
+            let numShieldsVisible = 0;
             for (let pointIndex = 0; pointIndex < path.length; ++pointIndex) {
                 const point = path[pointIndex];
 
@@ -1851,7 +1861,7 @@ export class TextElementsRenderer {
                         }
                     }
 
-                    // Place it as a point label if it's not to close to other marker in the
+                    // Place it as a point label if it's not to close to another marker in the
                     // same shield group.
                     if (!tooClose) {
                         if (
@@ -1866,10 +1876,16 @@ export class TextElementsRenderer {
                             )
                         ) {
                             shieldGroup.push(tempScreenPosition.x, tempScreenPosition.y);
+                            numShieldsVisible++;
                         }
                     }
                 }
             }
+            if (numShieldsVisible === 0) {
+                // For road shields the shared textRenderState may only be reset if none of the
+                // icons can be rendered.
+                labelState.reset();
+            }
         }
         // Process markers (without shield groups).
         else {