Data commit

Task/Draw-a-rotating-cube/Go/draw-a-rotating-cube.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/gif"
+	"log"
+	"math"
+	"os"
+)
+
+const (
+	width, height = 640, 640
+	offset        = height / 2
+	fileName      = "rotatingCube.gif"
+)
+
+var nodes = [][]float64{{-100, -100, -100}, {-100, -100, 100}, {-100, 100, -100}, {-100, 100, 100},
+	{100, -100, -100}, {100, -100, 100}, {100, 100, -100}, {100, 100, 100}}
+var edges = [][]int{{0, 1}, {1, 3}, {3, 2}, {2, 0}, {4, 5}, {5, 7}, {7, 6},
+	{6, 4}, {0, 4}, {1, 5}, {2, 6}, {3, 7}}
+
+func main() {
+	var images []*image.Paletted
+	fgCol := color.RGBA{0xff, 0x00, 0xff, 0xff}
+	var palette = []color.Color{color.RGBA{0x00, 0x00, 0x00, 0xff}, fgCol}
+	var delays []int
+
+	imgFile, err := os.Create(fileName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer imgFile.Close()
+
+	rotateCube(math.Pi/4, math.Atan(math.Sqrt(2)))
+	var frame float64
+	for frame = 0; frame < 360; frame++ {
+		img := image.NewPaletted(image.Rect(0, 0, width, height), palette)
+		images = append(images, img)
+		delays = append(delays, 5)
+		for _, edge := range edges {
+			xy1 := nodes[edge[0]]
+			xy2 := nodes[edge[1]]
+			drawLine(int(xy1[0])+offset, int(xy1[1])+offset, int(xy2[0])+offset, int(xy2[1])+offset, img, fgCol)
+		}
+		rotateCube(math.Pi/180, 0)
+	}
+	if err := gif.EncodeAll(imgFile, &gif.GIF{Image: images, Delay: delays}); err != nil {
+		imgFile.Close()
+		log.Fatal(err)
+	}
+
+}
+
+func rotateCube(angleX, angleY float64) {
+	sinX := math.Sin(angleX)
+	cosX := math.Cos(angleX)
+	sinY := math.Sin(angleY)
+	cosY := math.Cos(angleY)
+	for _, node := range nodes {
+		x := node[0]
+		y := node[1]
+		z := node[2]
+		node[0] = x*cosX - z*sinX
+		node[2] = z*cosX + x*sinX
+		z = node[2]
+		node[1] = y*cosY - z*sinY
+		node[2] = z*cosY + y*sinY
+	}
+}
+
+func drawLine(x0, y0, x1, y1 int, img *image.Paletted, col color.RGBA) {
+	dx := abs(x1 - x0)
+	dy := abs(y1 - y0)
+	var sx, sy int = -1, -1
+	if x0 < x1 {
+		sx = 1
+	}
+	if y0 < y1 {
+		sy = 1
+	}
+	err := dx - dy
+	for {
+		img.Set(x0, y0, col)
+		if x0 == x1 && y0 == y1 {
+			break
+		}
+		e2 := 2 * err
+		if e2 > -dy {
+			err -= dy
+			x0 += sx
+		}
+		if e2 < dx {
+			err += dx
+			y0 += sy
+		}
+	}
+}
+
+func abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}