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2022-01-14 12:46:28 +0100 CET

# AoC 2021 day 9 - 3D print of cave height map

After solving the puzzle of day 9 about a cave with basins and heights from 0 to 9, we1 thought about 3D printing the input as height map.

## Go program

I generated an STL model using the puzzle input as list of lines:

``````func renderSTL(input []string) {
filename := "day09.stl"

// list of all generated boxes
boxes := make([]sdf.SDF3, 0)

// base plate on which the height 0 begins
plate2d := sdf.Box2D(sdf.V2{float64(len(input)), float64(len(input))}, 1)
plate3d := sdf.Extrude3D(plate2d, 2.0)
// Move plate completely to the positive space. Initially the center of the
// plate is positioned at the origin.
plateM := sdf.Translate3d(sdf.V3{
float64(len(input)) / 2,
float64(len(input)) / 2,
0,
})

boxes = append(boxes, sdf.Transform3D(plate3d, plateM))
for y, row := range input {
for x, cell := range row {
if cell == '0' {
continue
}
num, err := strconv.Atoi(string(cell))
if err != nil {
fmt.Printf("error converting %d\n", cell)
return
}
box2d := sdf.Box2D(sdf.V2{1, 1}, 0)
// add one so level 0 has one unit
height := float64(num + 1)
box3d := sdf.Extrude3D(box2d, height)
m := sdf.Translate3d(sdf.V3{float64(x), float64(y), height / 2})
boxes = append(boxes, sdf.Transform3D(box3d, m))

}
}

fmt.Printf("generated %d boxes\n", len(boxes))
start := time.Now()
render.RenderSTL(sdf.Union3D(boxes...), 400, filename)
fmt.Printf("needed %s\n", time.Since(start))
}
`````` ## Impressions   1. credits to Markus