commit f88f7f9d125bc6af5ca158d7388bc6c6cf462777
Author: silva guimaraes <silva__guimaraes@hotmail.com>
Date:   Thu Aug 17 13:30:39 2023 -0300

    commit inicial

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..5bc21b6
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module barnes-hut
+
+go 1.20
+
+require github.com/gen2brain/raylib-go/raylib v0.0.0-20230719211022-1083eace2049
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..5f40ca5
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/gen2brain/raylib-go/raylib v0.0.0-20230719211022-1083eace2049 h1:fJeDPYJDyT+KeWKsIMbRlNcSgsQ2nZ4bJLwBraVA/xU=
+github.com/gen2brain/raylib-go/raylib v0.0.0-20230719211022-1083eace2049/go.mod h1:AwtGA3aTtYdezNxEVbfchaLw/z+CuRDh2Mlxy0FbBro=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..c10ff96
--- /dev/null
+++ b/main.go
@@ -0,0 +1,140 @@
+package main
+
+// veja:
+// The relationship between chaos, fractal and physics
+// https://www.youtube.com/watch?v=C5Jkgvw-Z6E
+
+import (
+	// "fmt"
+	"fmt"
+	"math"
+	"math/rand"
+	"strconv"
+
+	// "math/rand"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+
+type magnet struct {
+    pos rl.Vector2
+    speed rl.Vector2
+    color rl.Color
+    // force float32
+    // radius float32
+}
+
+// type ball struct {
+//     pos rl.Vector2
+//     originGrid rl.Vector2
+//     radius float32
+//     speed rl.Vector2
+//     steps int
+// }
+
+// parâmetros
+const initalMagnetCount = 100
+const windowWidth = 700
+const windowHeight = 700
+const magnetRadius = 5 
+const gravConst float32 = 10
+
+// func insideArea(pos rl.Vector2) (bool, bool) {
+//     return pos.X > 0 && pos.X < windowWidth, pos.Y > 0 && pos.Y < windowHeight
+// }
+
+func (m *magnet) update(magnets []*magnet) {
+    magnetsPull := rl.Vector2{}
+
+    for _, magnet := range magnets {
+        if m == magnet { continue }
+
+        direction := rl.Vector2Normalize(rl.Vector2Subtract(m.pos, magnet.pos))
+        distance := rl.Vector2Distance(magnet.pos, m.pos)
+        if (distance < magnetRadius*2) {
+            // direction = rl.Vector2Negate(direction)
+            continue
+        }
+        distanceSquared := math.Pow(float64(distance), 2)
+        force := gravConst / float32(distanceSquared)
+
+        acceleration := rl.Vector2Scale(direction, -force)
+
+        magnetsPull = rl.Vector2Add(magnetsPull, acceleration)
+    }
+
+    m.speed = rl.Vector2Add(m.speed, magnetsPull)
+    newPos := rl.Vector2Add(m.speed, m.pos)
+
+    // x, y := insideArea(newPos)    
+    // if !x { newPos.X = -newPos.X; m.speed.X = 0 }
+    // if !y { newPos.Y = -newPos.Y; m.speed.Y = 0 }
+
+    m.pos = newPos
+}
+
+func randomMagnet() *magnet {
+    newMagnet := magnet{
+        pos: rl.Vector2{
+            X: float32(rand.Intn(windowWidth - 100) + 50),
+            Y: float32(rand.Intn(windowHeight - 100) + 50),
+        },
+        color: rl.NewColor(
+            uint8(rand.Int()),
+            uint8(rand.Int()),
+            uint8(rand.Int()),
+            255,
+        ),
+    }
+    return &newMagnet
+}
+
+func createMagnets(n int) []*magnet {
+    var magnets []*magnet
+
+    for i := 0; i < n; i++ {
+        magnets = append(magnets, randomMagnet())
+    }
+    return magnets
+}
+
+func main() {
+	rl.InitWindow(
+        windowWidth, windowHeight, 
+        "barnes hut",
+    )
+	defer rl.CloseWindow()
+	rl.SetTargetFPS(60)
+
+    magnets := createMagnets(initalMagnetCount)
+
+	for !rl.WindowShouldClose() {
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.Black)
+        rl.DrawFPS(0, 0)
+
+// func rl.DrawText(text string, posX int32, posY int32, fontSize int32, col color.RGBA)
+        rl.DrawText(strconv.Itoa(len(magnets)), 0, 20, 20, rl.White)
+
+        {
+            if rl.IsKeyPressed(rl.KeyR) {
+                magnets = createMagnets(len(magnets))
+            }
+            if rl.IsKeyPressed(rl.KeyW) {
+                magnets = append(magnets, createMagnets(100)...)
+            }
+        }
+
+        for _, magnet := range magnets {
+            magnet.update(magnets)
+            rl.DrawCircleV(magnet.pos, magnetRadius+1, rl.White)
+            rl.DrawCircleV(magnet.pos, magnetRadius, magnet.color)
+        }
+
+        rl.EndDrawing()
+	}
+
+    fmt.Println("hello world")
+
+}