initial working sketch in go on raylib

main.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"fmt"
+	"github.com/gen2brain/raylib-go/raylib"
+	"github.com/ojrac/opensimplex-go"
+)
+
+func main() {
+
+	const (
+		screenWidth  = 2200
+		screenHeight = 1200
+	)
+
+	rl.InitWindow(screenWidth, screenHeight, "sumi sierpinski arrow")
+
+	var camera rl.Camera2D
+	camera.Zoom = 1.0
+
+	rl.SetTargetFPS(60)
+
+	angles := make([]float32, 1000)
+	noise := opensimplex.NewNormalized(0)
+	for i := range len(angles) {
+		angles[i] = float32(noise.Eval2(float64(i)*0.0001, 0.00)) * 2 - 1
+		fmt.Printf("angles[%d] = %.2f\n", i, angles[i])
+	}
+
+	frameNum := 0
+
+	for !rl.WindowShouldClose() {
+
+		frameNum++
+
+		if rl.IsMouseButtonDown(rl.MouseRightButton) {
+			delta := rl.GetMouseDelta()
+			delta = rl.Vector2Scale(delta, -1.0/camera.Zoom)
+			camera.Target = rl.Vector2Add(camera.Target, delta)
+		}
+
+		// Zoom based on mouse wheel
+		wheel := rl.GetMouseWheelMove()
+		if wheel != 0 {
+			// Get the world point that is under the mouse
+			mouseWorldPos := rl.GetScreenToWorld2D(rl.GetMousePosition(), camera)
+
+			// Set the offset to where the mouse is
+			camera.Offset = rl.GetMousePosition()
+
+			// Set the target to match, so that the camera maps the world space point
+			// under the cursor to the screen space point under the cursor at any zoom
+			camera.Target = mouseWorldPos
+
+			// Zoom increment
+			const zoomIncrement float32 = 0.125
+
+			camera.Zoom += (wheel * zoomIncrement)
+			if camera.Zoom < zoomIncrement {
+				camera.Zoom = zoomIncrement
+			}
+		}
+
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.RayWhite)
+
+		rl.BeginMode2D(camera)
+
+		rl.PushMatrix()
+		rl.Translatef(screenWidth/2, screenHeight/2, 0);
+
+		// initial transform by halfway again through angle array
+
+		angleIndex := frameNum%len(angles)
+		angle := angles[angleIndex]
+
+		initAngle := angles[(angleIndex + len(angles)/2)%len(angles)]
+		rl.Rotatef(250*initAngle, 0, 0, 1)
+		rl.Translatef(100*initAngle, 100*initAngle, 0)
+
+		for range 1000 {
+			rl.DrawLine(0, 0, 10, 0, rl.Black)
+			rl.Translatef(10, 0, 0)
+			rl.Rotatef(angle, 0, 0, 1)
+			angleIndex++
+			angleIndex = angleIndex%len(angles)
+			angle += angles[angleIndex]
+		}
+		rl.PopMatrix()
+
+		/*
+		rl.PushMatrix()
+		rl.Translatef(0, 25*50, 0)
+		rl.Rotatef(90, 1, 0, 0)
+		rl.DrawGrid(100, 50)
+		rl.PopMatrix()
+		*/
+
+		rl.EndMode2D()
+
+		rl.DrawText("Mouse right button drag to move, mouse wheel to zoom", 10, 10, 20, rl.White)
+
+		rl.EndDrawing()
+	}
+
+	rl.CloseWindow()
+}
+