load GeoJSON polygons and multi polygons

src/data.cc

@@ -14,6 +14,7 @@
 #include "data.h"
 #include "utils/fileutil.h"
 #include "utils/csv.h"
+#include "utils/geojson.h"
 #include "sexpr_conv.h"
 #include "sexpr_util.h"
 #include <assert.h>
@@ -184,6 +185,51 @@ ReturnCode data_load_strings(
   return expr_to_strings(expr, values);
 }
 
+ReturnCode data_load_polys2_geojson(
+    const Expr* expr,
+    std::vector<Poly2>* data) {
+  if (!expr || !expr_is_value(expr)) {
+    return errorf(
+        ERROR,
+        "argument error; expected a filename, got: {}",
+        expr_inspect(expr));
+  }
+
+  const auto& path = expr_get_value(expr);
+
+  GeoJSONReader reader;
+  reader.on_polygons = [data] (const Poly3* polys, size_t poly_count) {
+    for (size_t i = 0; i < poly_count; ++i) {
+      data->emplace_back(poly3_to_poly2(polys[i]));
+    }
+
+    return OK;
+  };
+
+  return geojson_read_file(path, reader);
+}
+
+ReturnCode data_load_polys2(
+    const Expr* expr,
+    std::vector<Poly2>* data) {
+  if (!expr || !expr_is_list(expr) || !expr_get_list(expr)) {
+    return errorf(
+        ERROR,
+        "argument error; expected a list, got: {}",
+        expr_inspect(expr));
+  }
+
+  auto args = expr_get_list(expr);
+
+  if (args && expr_is_value_literal(args, "geojson")) {
+    return data_load_polys2_geojson(expr_next(args), data);
+  }
+
+  return err_invalid_value(expr_inspect(expr), {
+    "geojson"
+  });
+}
+
 ReturnCode data_load(
     const Expr* expr,
     std::vector<Measure>* values) {

src/data.h

@@ -52,6 +52,10 @@ ReturnCode data_load_strings(
     const Expr* expr,
     std::vector<std::string>* values);
 
+ReturnCode data_load_polys2(
+    const Expr* expr,
+    std::vector<Poly2>* data);
+
 ReturnCode data_load(
     const Expr* expr,
     std::vector<Measure>* values);

src/graphics/geometry.cc

@@ -48,5 +48,26 @@ std::ostream& operator <<(std::ostream& os, const Rectangle& r) {
   return os;
 }
 
+PolyLine2 polyline3_to_polyline2(const PolyLine3& p) {
+  PolyLine2 p2;
+
+  for (const auto& x : p.vertices) {
+    p2.vertices.emplace_back(x);
+  }
+
+  return p2;
+}
+
+Poly2 poly3_to_poly2(const Poly3& p) {
+  Poly2 p2;
+  p2.boundary = polyline3_to_polyline2(p.boundary);
+
+  for (const auto& x : p.holes) {
+    p2.holes.emplace_back(polyline3_to_polyline2(x));
+  }
+
+  return p2;
+}
+
 } // namespace clip
 

src/graphics/geometry.h

@@ -16,6 +16,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <iostream>
+#include <vector>
 #include "vmath.h"
 
 namespace clip {
@@ -33,5 +34,33 @@ struct Rectangle {
 
 std::ostream& operator <<(std::ostream& os, const Rectangle& c);
 
+struct PolyLine2 {
+  std::vector<vec2> vertices;
+};
+
+struct PolyLine3 {
+  std::vector<vec3> vertices;
+};
+
+/**
+ * - The poly lines are assumed to form closed 'rings'.
+ */
+struct Poly2 {
+  PolyLine2 boundary;
+  std::vector<PolyLine2> holes;
+};
+
+/**
+ * - The poly lines are assumed to form closed 'rings'.
+ */
+struct Poly3 {
+  PolyLine3 boundary;
+  std::vector<PolyLine3> holes;
+};
+
+PolyLine2 polyline3_to_polyline2(const PolyLine3& p);
+
+Poly2 poly3_to_poly2(const Poly3& p);
+
 } // namespace clip