first commit

README.md

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+# spritesheet_generator
+
+This is a simple program to generate a template for isometric sprite 
+tilesheets, in png format. For use with software such as [Tiled](https://www.mapeditor.org).
+
+## Installation
+
+`go install github.com/tardisx/spritesheet_generator@latest`
+
+If you really want binaries, pester me :-)
+
+## Usage
+
+`Usage of ./spritesheet_generator:
+  -height int
+    	base tile height in pixels (default 128)
+  -multiplier int
+    	tile height multiplier (default 2)
+  -output string
+    	output filename
+  -width int
+    	tile width in pixels (default 128)
+  -x int
+    	number of tiles across (default 8)
+  -y int
+    	number of tiles down (default 8)`
+
+Hopefully these options are mostly self-explanatory.
+
+The `multiplier` option describes how 'tall' the tiles are. Normally you
+want some height to tiles to give them the illusion of depth and the ability
+to hide things behind them. If you are unsure, start with the default of 2.
+
+## Example
+
+![Screenshot][screenshot]
+
+
+[screenshot]: https://raw.githubusercontent.com/tardisx/spritesheet_generator/main/example.png

go.mod

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+module github.com/tardisx/spritesheet_generator
+
+go 1.19
+
+require golang.org/x/image v0.2.0

go.sum

@@ -0,0 +1,26 @@
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/image v0.2.0 h1:/DcQ0w3VHKCC5p0/P2B0JpAZ9Z++V2KOo2fyU89CXBQ=
+golang.org/x/image v0.2.0/go.mod h1:la7oBXb9w3YFjBqaAwtynVioc1ZvOnNteUNrifGNmAI=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.5.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
+	"golang.org/x/image/math/fixed"
+)
+
+type tile struct {
+	X int
+	Y int
+}
+
+type pt struct {
+	x int
+	y int
+}
+
+func main() {
+
+	var tileWidth, tileHeight, multiplier int
+	var xTiles, yTiles int
+	var output string
+
+	flag.IntVar(&tileWidth, "width", 128, "tile width in pixels")
+	flag.IntVar(&tileHeight, "height", 128, "base tile height in pixels")
+	flag.IntVar(&multiplier, "multiplier", 2, "tile height multiplier")
+	flag.IntVar(&xTiles, "x", 8, "number of tiles across")
+	flag.IntVar(&yTiles, "y", 8, "number of tiles down")
+	flag.StringVar(&output, "output", "", "output filename")
+
+	flag.Parse()
+
+	if output == "" {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	t := tile{tileWidth, tileHeight}
+
+	width := xTiles * t.X
+	height := yTiles * t.Y
+
+	upLeft := image.Point{0, 0}
+	lowRight := image.Point{width, height}
+
+	img := image.NewRGBA(image.Rectangle{upLeft, lowRight})
+
+	for x := 0; x < xTiles; x++ {
+		for y := 0; y < yTiles; y++ {
+			drawDiamond(img, t, x, y, multiplier)
+		}
+	}
+
+	// Encode as PNG.
+	f, err := os.Create(output)
+	if err != nil {
+		fmt.Printf("could not output to %s - %s", output, err)
+		os.Exit(1)
+	}
+	png.Encode(f, img)
+	f.Close()
+}
+
+func drawDiamond(img *image.RGBA, t tile, x int, y int, multiplier int) {
+
+	tileX := x * t.X
+	tileY := y * t.Y
+
+	yTop := t.Y - (t.Y / multiplier)
+	yMid := t.Y - (t.Y / (multiplier * 2))
+
+	pt1 := pt{tileX, tileY + yMid}           // left middle
+	pt2 := pt{tileX + t.X/2, tileY + t.Y}    // bottom
+	pt3 := pt{tileX + t.X - 1, tileY + yMid} // right
+	pt4 := pt{tileX + t.X/2, tileY + yTop}   // top
+
+	drawLine(img, pt1.x, pt1.y, pt2.x, pt2.y, color.Black)
+	drawLine(img, pt2.x, pt2.y, pt3.x, pt3.y, color.Black)
+	drawLine(img, pt3.x, pt3.y, pt4.x, pt4.y, color.Black)
+	drawLine(img, pt4.x, pt4.y, pt1.x, pt1.y, color.Black)
+	addLabel(img, tileX+t.X/2-10, tileY+30, fmt.Sprintf("%d,%d", x, y))
+
+	// tl => bl
+	drawLine(img, tileX, tileY, tileX, tileY+t.Y-1, color.White)
+	// bl => br
+	drawLine(img, tileX, tileY+t.Y-1, tileX+t.X-1, tileY+t.Y-1, color.White)
+	// br => tr
+	drawLine(img, tileX+t.X-1, tileY+t.Y-1, tileX+t.X-1, tileY, color.White)
+	// tr => tl
+	drawLine(img, tileX+t.X-1, tileY, tileX, tileY, color.White)
+
+}
+
+// thanks to https://github.com/StephaneBunel/bresenham
+func drawLine(img *image.RGBA, x1, y1, x2, y2 int, col color.Color) {
+	var dx, dy, e, slope int
+
+	// Because drawing p1 -> p2 is equivalent to draw p2 -> p1,
+	// I sort points in x-axis order to handle only half of possible cases.
+	if x1 > x2 {
+		x1, y1, x2, y2 = x2, y2, x1, y1
+	}
+
+	dx, dy = x2-x1, y2-y1
+	// Because point is x-axis ordered, dx cannot be negative
+	if dy < 0 {
+		dy = -dy
+	}
+
+	switch {
+
+	// Is line a point ?
+	case x1 == x2 && y1 == y2:
+		img.Set(x1, y1, col)
+
+	// Is line an horizontal ?
+	case y1 == y2:
+		for ; dx != 0; dx-- {
+			img.Set(x1, y1, col)
+			x1++
+		}
+		img.Set(x1, y1, col)
+
+	// Is line a vertical ?
+	case x1 == x2:
+		if y1 > y2 {
+			y1, y2 = y2, y1
+		}
+		for ; dy != 0; dy-- {
+			img.Set(x1, y1, col)
+			y1++
+		}
+		img.Set(x1, y1, col)
+
+	// Is line a diagonal ?
+	case dx == dy:
+		if y1 < y2 {
+			for ; dx != 0; dx-- {
+				img.Set(x1, y1, col)
+				x1++
+				y1++
+			}
+		} else {
+			for ; dx != 0; dx-- {
+				img.Set(x1, y1, col)
+				x1++
+				y1--
+			}
+		}
+		img.Set(x1, y1, col)
+
+	// wider than high ?
+	case dx > dy:
+		if y1 < y2 {
+			// BresenhamDxXRYD(img, x1, y1, x2, y2, col)
+			dy, e, slope = 2*dy, dx, 2*dx
+			for ; dx != 0; dx-- {
+				img.Set(x1, y1, col)
+				x1++
+				e -= dy
+				if e < 0 {
+					y1++
+					e += slope
+				}
+			}
+		} else {
+			// BresenhamDxXRYU(img, x1, y1, x2, y2, col)
+			dy, e, slope = 2*dy, dx, 2*dx
+			for ; dx != 0; dx-- {
+				img.Set(x1, y1, col)
+				x1++
+				e -= dy
+				if e < 0 {
+					y1--
+					e += slope
+				}
+			}
+		}
+		img.Set(x2, y2, col)
+
+	// higher than wide.
+	default:
+		if y1 < y2 {
+			// BresenhamDyXRYD(img, x1, y1, x2, y2, col)
+			dx, e, slope = 2*dx, dy, 2*dy
+			for ; dy != 0; dy-- {
+				img.Set(x1, y1, col)
+				y1++
+				e -= dx
+				if e < 0 {
+					x1++
+					e += slope
+				}
+			}
+		} else {
+			// BresenhamDyXRYU(img, x1, y1, x2, y2, col)
+			dx, e, slope = 2*dx, dy, 2*dy
+			for ; dy != 0; dy-- {
+				img.Set(x1, y1, col)
+				y1--
+				e -= dx
+				if e < 0 {
+					x1++
+					e += slope
+				}
+			}
+		}
+		img.Set(x2, y2, col)
+	}
+}
+
+func addLabel(img *image.RGBA, x, y int, label string) {
+	col := color.RGBA{20, 20, 240, 255}
+	point := fixed.Point26_6{X: fixed.I(x), Y: fixed.I(y)}
+
+	d := &font.Drawer{
+		Dst:  img,
+		Src:  image.NewUniform(col),
+		Face: basicfont.Face7x13,
+		Dot:  point,
+	}
+	d.DrawString(label)
+}
+
+// // Colors are defined by Red, Green, Blue, Alpha uint8 values.
+// cyan := color.RGBA{100, 200, 200, 0xff}
+
+// // Set color for each pixel.
+// for x := 0; x < width; x++ {
+// 	for y := 0; y < height; y++ {
+// 		switch {
+// 		case x < width/2 && y < height/2: // upper left quadrant
+// 			img.Set(x, y, cyan)
+// 		case x >= width/2 && y >= height/2: // lower right quadrant
+// 			img.Set(x, y, color.White)
+// 		default:
+// 			// Use zero value.
+// 		}
+// 	}
+// }