Finished MathUtils.changeLineLength

build.sbt

@@ -1,6 +1,6 @@
 name := "sgine"
 ThisBuild / organization := "org.sgine"
-ThisBuild / version := "2.0.0b3"
+ThisBuild / version := "2.0.0b4-SNAPSHOT"
 
 val scala213 = "2.13.11"
 

core/src/main/scala/org/sgine/util/MathUtils.scala

@@ -4,6 +4,10 @@ import com.badlogic.gdx.math.{Intersector, Vector2}
 import org.sgine.component.{Component, DimensionedSupport}
 
 object MathUtils {
+  private lazy val t1: Vector2 = new Vector2()
+  private lazy val t2: Vector2 = new Vector2()
+  private lazy val t3: Vector2 = new Vector2()
+
   def distance(x1: Double, y1: Double, x2: Double, y2: Double): Double =
     math.sqrt(math.pow(x2 - x1, 2.0) + math.pow(y2 - y1, 2.0))
 
@@ -17,27 +21,25 @@ object MathUtils {
   }
 
   def changeLineLength(x1: Double, y1: Double, x2: Double, y2: Double, length: Double): (Double, Double) = {
-    // TODO: keep the trajectory, but change the length of the line's endpoint
-    (x2, y2)
+    val currentLength = math.sqrt(math.pow(x2 - x1, 2.0) + math.pow(y2 - y1, 2.0))
+    val nx = x2 + (x2 - x1) / currentLength * length
+    val ny = y2 + (y2 - y1) / currentLength * length
+    (nx, ny)
   }
 
-  private lazy val start: Vector2 = new Vector2()
-  private lazy val end: Vector2 = new Vector2()
-  private lazy val center: Vector2 = new Vector2()
-
   def intersectSegmentCircle(x1: Double,
                              y1: Double,
                              x2: Double,
                              y2: Double,
                              circleX: Double,
                              circleY: Double,
                              circleRadius: Double): Boolean = {
-    start.x = x1.toFloat
-    start.y = y1.toFloat
-    end.x = x2.toFloat
-    end.y = y2.toFloat
-    center.x = circleX.toFloat
-    center.y = circleY.toFloat
-    Intersector.intersectSegmentCircle(start, end, center, circleRadius.toFloat)
+    t1.x = x1.toFloat
+    t1.y = y1.toFloat
+    t2.x = x2.toFloat
+    t2.y = y2.toFloat
+    t3.x = circleX.toFloat
+    t3.y = circleY.toFloat
+    Intersector.intersectSegmentCircle(t1, t2, t3, math.pow(circleRadius, 2.0).toFloat)
   }
 }

core/src/test/scala/examples/TargetingExample.scala

@@ -45,6 +45,25 @@ object TargetingExample extends Example {
           val y = global.localizeY(target.global.middle)
           drawer.color = Color.Green
           drawer.line(110.0, 110.0, x, y, 6.0)
+          val (fx, fy) = MathUtils.changeLineLength(110.0, 110.0, x, y, 1000.0)
+          drawer.color = Color.Blue
+          drawer.line(110.0, 110.0, fx, fy, 6.0)
+          enemies.foreach { e =>
+            val gx1 = global.center
+            val gy1 = global.middle
+            val gx2 = global.x + fx
+            val gy2 = global.y + fy
+            val intersecting = MathUtils.intersectSegmentCircle(
+              x1 = gx1,
+              y1 = gy1,
+              x2 = gx2,
+              y2 = gy2,
+              circleX = e.global.center,
+              circleY = e.global.middle,
+              circleRadius = 110.0
+            )
+            e.intersecting @= intersecting
+          }
         }
       }
 
@@ -61,6 +80,8 @@ object TargetingExample extends Example {
     private val r1 = Random.nextDouble()
     private val r2 = Random.nextDouble()
 
+    val intersecting: Var[Boolean] = Var(false)
+
     center := r1 * screen.width
     middle := r2 * screen.height
     width @= 200.0
@@ -78,19 +99,21 @@ object TargetingExample extends Example {
           } else {
             Color.Red
           }
+        } else if (intersecting()) {
+          Color.Blue
         } else {
           Color.White
         }
       }
     }
 
-    private lazy val text = new Label("Testing") {
+    private lazy val text = new Label {
       font @= Fonts.OpenSans.Regular.small
       color @= Color.White
       center @= 100.0
       middle @= 100.0
 
-      this.text := s"d: ${distance().f()}"
+      this.text := distance().f()
     }
 
     override lazy val children: Children[Component] = Children(