Add AxisAlignedBox::fromPoints

CHANGES.md

@@ -13,6 +13,7 @@
 - Added support for `3DTILES_ellipsoid` in `Cesium3DTiles`, `Cesium3DTilesReader`, and `Cesium3DTilesWriter`.
 - Added support for `3DTILES_content_voxels` in `Cesium3DTiles`, `Cesium3DTilesReader`, and `Cesium3DTilesWriter`.
 - Added generated classes for `EXT_primitive_voxels` and its dependencies in `CesiumGltf`, `CesiumGltfReader`, and `CesiumGltfWriter`.
+- Added `AxisAlignedBox::fromPositions`, which creates an `AxisAlignedBox` from an input vector of positions.
 
 ##### Fixes :wrench:
 

CesiumGeometry/include/CesiumGeometry/AxisAlignedBox.h

@@ -1,9 +1,12 @@
 #pragma once
 
-#include <CesiumGeometry/Library.h>
+#include "Library.h"
 
+#include <glm/common.hpp>
 #include <glm/vec3.hpp>
 
+#include <vector>
+
 namespace CesiumGeometry {
 
 /**
@@ -120,6 +123,30 @@ struct CESIUMGEOMETRY_API AxisAlignedBox final {
            position.y >= this->minimumY && position.y <= this->maximumY &&
            position.z >= this->minimumZ && position.z <= this->maximumZ;
   }
+
+  /**
+   * @brief Creates a tight-fitting, axis-aligned bounding box that contains all
+   * of the input positions.
+   *
+   * @param positions The positions.
+   * @returns An axis-aligned bounding box derived from the input positions.
+   */
+  static AxisAlignedBox
+  fromPositions(const std::vector<glm::dvec3>& positions) {
+    if (positions.size() == 0) {
+      return AxisAlignedBox();
+    }
+
+    glm::dvec3 min = positions[0];
+    glm::dvec3 max = positions[0];
+
+    for (size_t i = 1; i < positions.size(); i++) {
+      min = glm::min(min, positions[i]);
+      max = glm::max(max, positions[i]);
+    }
+
+    return AxisAlignedBox(min.x, min.y, min.z, max.x, max.y, max.z);
+  }
 };
 
 } // namespace CesiumGeometry

CesiumGeometry/test/TestAxisAlignedBox.cpp

@@ -19,3 +19,44 @@ TEST_CASE("AxisAlignedBox constructor") {
   CHECK(aabb.lengthY == 5.0 - 2.0);
   CHECK(aabb.lengthZ == 6.0 - 3.0);
 }
+
+TEST_CASE("AxisAlignedBox fromPositions") {
+  SUBCASE("returns default box for empty vector") {
+    AxisAlignedBox aabb = AxisAlignedBox::fromPositions({});
+
+    CHECK(aabb.minimumX == 0.0);
+    CHECK(aabb.minimumY == 0.0);
+    CHECK(aabb.minimumZ == 0.0);
+    CHECK(aabb.maximumX == 0.0);
+    CHECK(aabb.maximumY == 0.0);
+    CHECK(aabb.maximumZ == 0.0);
+  }
+
+  SUBCASE("works for single position") {
+    glm::dvec3 position(1.0, 2.0, 3.0);
+    AxisAlignedBox aabb = AxisAlignedBox::fromPositions({position});
+
+    CHECK(aabb.minimumX == position.x);
+    CHECK(aabb.minimumY == position.y);
+    CHECK(aabb.minimumZ == position.z);
+    CHECK(aabb.maximumX == position.x);
+    CHECK(aabb.maximumY == position.y);
+    CHECK(aabb.maximumZ == position.z);
+  }
+
+  SUBCASE("works for multiple positions") {
+    std::vector<glm::dvec3> positions{
+        glm::dvec3(1.0, 2.0, 3.0),
+        glm::dvec3(-2.0, 0.4, -10.0),
+        glm::dvec3(0.1, 4.3, 11.0),
+        glm::dvec3(0.5, 0.5, 2.7)};
+
+    AxisAlignedBox aabb = AxisAlignedBox::fromPositions(positions);
+    CHECK(aabb.minimumX == -2.0);
+    CHECK(aabb.minimumY == 0.4);
+    CHECK(aabb.minimumZ == -10.0);
+    CHECK(aabb.maximumX == 1.0);
+    CHECK(aabb.maximumY == 4.3);
+    CHECK(aabb.maximumZ == 11.0);
+  }
+}