cube/chatgpt.go

package main

import (
	"image"
	"image/color"
	"image/draw"
	"math"

	"git.niplace.ru/XoxJlopeZi4BB/dev/fb"
)

var Width, Height = fb.Resolution()
const (
	cubeSize     = 50
	Zoom         = 1000.0
	FOV          = 350
	frameCount   = 120
	rotationStep = math.Pi / 60
)

type Point3D struct {
	X, Y, Z float64
}

type Point2D struct {
	X, Y int
}

func rotateX(p Point3D, angle float64) Point3D {
	cosA := math.Cos(angle)
	sinA := math.Sin(angle)
	return Point3D{
		X: p.X,
		Y: p.Y*cosA - p.Z*sinA,
		Z: p.Y*sinA + p.Z*cosA,
	}
}

func rotateY(p Point3D, angle float64) Point3D {
	cosA := math.Cos(angle)
	sinA := math.Sin(angle)
	return Point3D{
		X: p.X*cosA + p.Z*sinA,
		Y: p.Y,
		Z: -p.X*sinA + p.Z*cosA,
	}
}

func project(p Point3D) Point2D {
	scale := Zoom / (p.Z + FOV)
	return Point2D{
		X: int(p.X*scale + float64(Width)/2),
		Y: int(p.Y*scale + float64(Height)/2),
	}
}

func drawLine(img *image.Paletted, p1, p2 Point2D, col color.Color) {
	dx := abs(p2.X - p1.X)
	dy := abs(p2.Y - p1.Y)
	sx := -1
	if p1.X < p2.X {
		sx = 1
	}
	sy := -1
	if p1.Y < p2.Y {
		sy = 1
	}
	err := dx - dy

	for {
		img.Set(p1.X, p1.Y, col)
		if p1.X == p2.X && p1.Y == p2.Y {
			break
		}
		e2 := 2 * err
		if e2 > -dy {
			err -= dy
			p1.X += sx
		}
		if e2 < dx {
			err += dx
			p1.Y += sy
		}
	}
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

/*
func Map[S, T any](v S, f func(T) T) S {
}
*/

func main() {
	// Define the vertices of the cube
	vertices := []Point3D{
		{-cubeSize, -cubeSize, -cubeSize},
		{cubeSize, -cubeSize, -cubeSize},
		{cubeSize, cubeSize, -cubeSize},
		{-cubeSize, cubeSize, -cubeSize},
		{-cubeSize, -cubeSize, cubeSize},
		{cubeSize, -cubeSize, cubeSize},
		{cubeSize, cubeSize, cubeSize},
		{-cubeSize, cubeSize, cubeSize},
	}

	// Define the edges of the cube
	edges := [][2]int{
		{0, 1}, {1, 2}, {2, 3}, {3, 0},
		{4, 5}, {5, 6}, {6, 7}, {7, 4},
		{0, 4}, {1, 5}, {2, 6}, {3, 7},
	}

	// Palette for the GIF
	palette := []color.Color{color.Black, color.White}

	// Generate frames
	for i := 0; i < frameCount; i++ {
		angle := float64(i) * rotationStep
		img := image.NewPaletted(image.Rect(0, 0, Width, Height), palette)
		draw.Draw(img, img.Bounds(), &image.Uniform{color.Black}, image.Point{}, draw.Src)

		// Rotate and project vertices
		projVertices := make([]Point2D, len(vertices))
		for j, v := range vertices {
			rotated := rotateY(rotateX(v, angle), angle)
			projVertices[j] = project(rotated)
		}

		// Draw edges
		for _, edge := range edges {
			p1 := projVertices[edge[0]]
			p2 := projVertices[edge[1]]
			drawLine(img, p1, p2, color.White)
		}

		err := fb.Draw(img)
		if err != nil {
			panic(err)
		}
	}
}