From 2f51e457204306d1afb87759d2e13f431560c414 Mon Sep 17 00:00:00 2001
From: gamzeozgul <gamze.ozgul@hotmail.com>
Date: Sun, 13 Jul 2025 02:10:25 +0300
Subject: [PATCH] docs: add intersection examples to README and example
 directory

- Add comprehensive intersection example in README.md showing both line-polygon and line-line intersections
- Create example/example_intersection.go with working code examples
- Address issue #105 by providing clear documentation on how to calculate geometric intersections
- Examples include error handling and expected output for better user understanding
---
 README.md                       | 50 +++++++++++++++++++++++++++++++++
 example/example_intersection.go | 44 +++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 example/example_intersection.go

diff --git a/README.md b/README.md
index 3d1f505..f119b02 100644
--- a/README.md
+++ b/README.md
@@ -76,6 +76,56 @@ func main() {
 Example: geoencoding
 [example_encoding.go](https://github.com/spatial-go/geoos/example/example_encoding.go)
 
+Example: Calculating `intersection` of two geometries via `Geoos`
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/spatial-go/geoos/geoencoding"
+	"github.com/spatial-go/geoos/planar"
+)
+
+func main() {
+	// First, choose the default algorithm.
+	strategy := planar.NormalStrategy()
+	
+	// Create two geometries for intersection
+	// Example 1: Line intersecting with a polygon
+	polygon, _ := geoencoding.Decode([]byte(`POLYGON((0 0,0 1,0 2,0 3,1 3,1 2,1 1,2 1,2 2,3 2,3 1,4 1,4 2,5 2,5 1,5 0,4 0,3 0,2 0,1 0,0 0))`), geoencoding.WKT)
+	line, _ := geoencoding.Decode([]byte(`LINESTRING(-5 0, 5 5)`), geoencoding.WKT)
+	
+	// Calculate intersection
+	intersection, err := strategy.Intersection(polygon, line)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		return
+	}
+	
+	// Output result
+	result := string(geoencoding.Encode(intersection, geoencoding.WKT))
+	fmt.Printf("Intersection result: %s\n", result)
+	// Output: LINESTRING(0 2.5,1 3)
+	
+	// Example 2: Two lines intersecting at a point
+	line1, _ := geoencoding.Decode([]byte(`LINESTRING(0 0, 2 2)`), geoencoding.WKT)
+	line2, _ := geoencoding.Decode([]byte(`LINESTRING(0 2, 2 0)`), geoencoding.WKT)
+	
+	intersection2, err := strategy.Intersection(line1, line2)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		return
+	}
+	
+	result2 := string(geoencoding.Encode(intersection2, geoencoding.WKT))
+	fmt.Printf("Lines intersection: %s\n", result2)
+	// Output: POINT(1 1)
+}
+```
+
+[example_intersection.go](https://github.com/spatial-go/geoos/example/example_intersection.go)
+
 ## Maintainer
 
 [@spatial-go](https://github.com/spatial-go)。
diff --git a/example/example_intersection.go b/example/example_intersection.go
new file mode 100644
index 0000000..907fd8f
--- /dev/null
+++ b/example/example_intersection.go
@@ -0,0 +1,44 @@
+package main
+
+import (
+"fmt"
+
+"github.com/spatial-go/geoos/geoencoding"
+"github.com/spatial-go/geoos/planar"
+)
+
+func main() {
+// First, choose the default algorithm.
+strategy := planar.NormalStrategy()
+
+// Create two geometries for intersection
+// Example 1: Line intersecting with a polygon
+polygon, _ := geoencoding.Decode([]byte(`POLYGON((0 0,0 1,0 2,0 3,1 3,1 2,1 1,2 1,2 2,3 2,3 1,4 1,4 2,5 2,5 1,5 0,4 0,3 0,2 0,1 0,0 0))`), geoencoding.WKT)
+line, _ := geoencoding.Decode([]byte(`LINESTRING(-5 0, 5 5)`), geoencoding.WKT)
+
+// Calculate intersection
+intersection, err := strategy.Intersection(polygon, line)
+if err != nil {
+fmt.Printf("Error: %v\n", err)
+return
+}
+
+// Output result
+result := string(geoencoding.Encode(intersection, geoencoding.WKT))
+fmt.Printf("Intersection result: %s\n", result)
+// Output: LINESTRING(0 2.5,1 3)
+
+// Example 2: Two lines intersecting at a point
+line1, _ := geoencoding.Decode([]byte(`LINESTRING(0 0, 2 2)`), geoencoding.WKT)
+line2, _ := geoencoding.Decode([]byte(`LINESTRING(0 2, 2 0)`), geoencoding.WKT)
+
+intersection2, err := strategy.Intersection(line1, line2)
+if err != nil {
+fmt.Printf("Error: %v\n", err)
+return
+}
+
+result2 := string(geoencoding.Encode(intersection2, geoencoding.WKT))
+fmt.Printf("Lines intersection: %s\n", result2)
+// Output: POINT(1 1)
+}