sumi/main.go

package main

import (
	"fmt"
	"math"
	"github.com/gen2brain/raylib-go/raylib"
	"github.com/ojrac/opensimplex-go"
	"github.com/go-git/go-git/v6"
)

func HeadHash(repoPath string) (string, error) {
	r, err := git.PlainOpen(repoPath)
	if err != nil {
		return "", err
	}

	ref, err := r.Head()
	if err != nil {
		return "", err
	}

	return ref.Hash().String(), nil
}

func IsDirty(repoPath string) (bool, error) {
	r, err := git.PlainOpen(repoPath)
	if err != nil {
		return false, err
	}

	wt, err := r.Worktree()
	if err != nil {
		return false, err
	}

	status, err := wt.Status()
	if err != nil {
		return false, err
	}

	return !status.IsClean(), nil
}

func clamp01(v float64) float64 {
	if v < 0 {
		return 0
	}
	if v > 1 {
		return 1
	}
	return v
}

func GrayCurve(v, k float64) rl.Color {
	v = math.Pow(clamp01(v), k) // k < 1 boosts highlights, k > 1 boosts shadows
	c := uint8(v * 255)
	return rl.Color{R: c, G: c, B: c, A: 255}
}

func sierpinskiArrow(order int, length float64) {
	rl.Scalef(1, -1, 1)
	//rl.Rotatef(180, 0, 0, 1)
	if order == 0 {
		curve(order, length, 60)
	} else {
		rl.Rotatef(60, 0, 0, 1)
		curve(order, length, -60)
	}
}

func curve(order int, length float64, angle float64) {
	if order == 0 {
		len := int32(length)
		rl.DrawLine(0, 0, len, 0, rl.Black)
		rl.Translatef(float32(len), 0, 0)
	} else {
		curve(order - 1, length/2, -angle)
		rl.Rotatef(float32(angle), 0, 0, 1)
		curve(order - 1, length/2, angle)
		rl.Rotatef(float32(angle), 0, 0, 1)
		curve(order - 1, length/2, -angle)
	}
}

func main() {

	const (
		screenWidth  = 1200
		screenHeight = 700
	)

	rl.InitWindow(screenWidth, screenHeight, "sumi sierpinski arrow")

	var camera = rl.Camera2D {
		Target:   rl.Vector2{X: 0, Y: 0},
		Offset:   rl.Vector2{X: float32(screenWidth) / 2, Y: float32(screenHeight) / 2},
		Rotation: 0,
		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)*0.05, 0.00)) * 0.1 - 0.05
		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()

		/**
		for x := range screenWidth {
			for y := range screenHeight {
				sp := rl.Vector2 { X: float32(x), Y: float32(y) };
				wp := rl.GetScreenToWorld2D(sp, camera);
				normVal := noise.Eval2(float64(wp.X), float64(wp.Y))
				rl.DrawPixelV(wp, GrayCurve(normVal, 0.8));
			}
		}
		**/

		// 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(2500*initAngle, 0, 0, 1)
		rl.Translatef(100*initAngle, 100*initAngle, 0)

		stepSize := int32(1)
		for range 1000 {
			rl.DrawLine(0, 0, stepSize, 0, rl.Black)
			rl.Translatef(float32(stepSize), 0, 0)
			rl.Rotatef(angle, 0, 0, 1)
			angleIndex++
			angleIndex = angleIndex%len(angles)
			angle += angles[angleIndex]
		}
		rl.PopMatrix()


		rl.PushMatrix()

		//rl.Translatef(-screenWidth/2, screenHeight/2, 0)

		sierpinskiArrow(9,800)

		rl.PopMatrix()

		/*
		rl.PushMatrix()
		rl.Translatef(0, 25*50, 0)
		rl.Rotatef(90, 1, 0, 0)
		rl.DrawGrid(100, 50)
		rl.PopMatrix()
		*/

		rl.EndMode2D()

		if rl.IsKeyDown(rl.KeySpace) {
			//rl.TakeScreenshot("snapshot.png")
			img := rl.LoadImageFromScreen()
			defer rl.UnloadImage(img)
			rl.ExportImage(*img, "shot.png")

			dflag, err := IsDirty(".")

			if err == nil {

				if dflag {
					fmt.Printf("working tree is dirty\n")
				} else {
					fmt.Printf("working tree is clean\n")
				}

				hash, err := HeadHash(".")
				if err == nil {
					fmt.Printf("HEAD -> %s\n", hash)
				}
			}
		}

		rl.DrawText("Mouse right button drag to move, mouse wheel to zoom", 10, 10, 20, rl.White)

		rl.EndDrawing()
	}

	rl.CloseWindow()
}