CesiumGeoJsonDocumentRasterOverlay support issue for MultiPolygon

[yuxueliyuxl]

What happened?

CesiumGeoJsonDocumentRasterOverlay support issue for MultiPolygon

Environment

Cesium for Unreal version:2.18
Unreal Engine Version:5.5
Operating System:window10

Reproduction steps

...

Supporting evidence

QGIS:

UE:

geojson :

TH.zip

[yuxueliyuxl]

After analysis:
The drawPolygon method of VectorRasterizer in Cesium-native is drawn using the blend2d fillPolygon method, and the fillPolygon processing of the multi-Rings is not ideal, so it is perfectly solved after the fillPath method is drawn.

[j9liu]

Hi @yuxueliyuxl, thanks for filing this report with detailed information.

@azrogers can you triage this issue to reproduce the behavior and test the user's fix? If the fix makes sense, let's bring it into the plugin.

[azrogers]

I'm sorry, I'm not clear on how the issue occurred or what the fix was that @yuxueliyuxl is describing here. Could you provide more information?

[yuxueliyuxl]

I'm sorry, I'm not clear on how the issue occurred or what the fix was that @yuxueliyuxl is describing here. Could you provide more information?

@azrogers I rewrote the drawPolygon method：

void VectorRasterizer::drawPolygon(
const std::vector<std::vectorglm::dvec3>& polygon,
const PolygonStyle& style) {
if (this->_finalized || (!style.fill && !style.outline)) {
return;
}

BLPath path;

// 遍历每个环（外环和内环）
for (const std::vectorglm::dvec3& ring : polygon) {
// 跳过空环
if (ring.empty())
continue;

// 使用反向迭代器（GeoJSON多边形顺序与blend2d相反）
auto it = ring.rbegin();
auto end = ring.rend();

// 移动到第一个点
glm::dvec3 firstPoint = *it;
BLPoint start = radiansToPoint(
    CesiumUtility::Math::degreesToRadians(firstPoint.x),
    CesiumUtility::Math::degreesToRadians(firstPoint.y),
    this->_bounds,
    this->_context);
path.moveTo(start);
++it;

// 添加环的其余点
for (; it != end; ++it) {
  BLPoint pt = radiansToPoint(
      CesiumUtility::Math::degreesToRadians(it->x),
      CesiumUtility::Math::degreesToRadians(it->y),
      this->_bounds,
      this->_context);
  path.lineTo(pt);
}

// 闭合当前环（连接回起点）
path.close();

}

// 设置奇偶填充规则（确保孔洞正确处理）
this->_context.setFillRule(BL_FILL_RULE_EVEN_ODD);

// 填充多边形（如果有填充样式）
if (style.fill) {
this->_context.fillPath(path, BLRgba32(style.fill->getColor().toRgba32()));
}

// 描边多边形（如果有描边样式）
if (style.outline) {
// 保存当前上下文状态
this->_context.save();

// 设置描边样式
setStrokeWidth(
    this->_context,
    *style.outline,
    this->_ellipsoid,
    this->_bounds);

// 描边路径
this->_context.strokePath(
    path,
    BLRgba32(style.outline->getColor().toRgba32()));

// 恢复上下文状态
this->_context.restore();

}
}