#SketchPad

CLI and Library for generating 3D asset files with a SwiftUI-like DSL.

The focus is .usda files, but also can generate X3D files.

Example Usage

Running a script

cd $PROJECT_DIR
swift run sketchpad multiball -s

Will run the multiball script, creating a usd file and and x3d file with default names in the directory.

Not specifying multiball means whatever sketch I currently left as the default sketch will run. Will likely be the contents of ScratchPad.

Writing a Sketch

Here is an example Sketch. Currently there is no Protocol, but so far the convention is that there must be a function called buildStage() that returns a Layer.

public struct RandomShell {
    public init(count:Int, radius:Double, ratio:Double = 0.1) {
        self.count = count
        self.radius = radius
        self.ratio = ratio
    }
    let count:Int
    let radius:Double
    let ratio:Double

    let tau = Double.pi * 2
    let π = Double.pi

    public func buildStage() -> some Layer {
        let sun_color = 0.9
        let sphere_radius = radius*ratio
        return Stage {
            Sphere(radius: sphere_radius).color(red: sun_color, green: sun_color, blue: sun_color)
             for _ in 0..<count {
                 let theta = Double.random(in: 0...π)
                 let phi = Double.random(in: 0...tau)
                 let x = radius * sin(theta) * cos(phi)
                 let y = radius * sin(theta) * sin(phi)
                 let z = radius * cos(theta)
                 
                 Sphere(radius: sphere_radius)
                 .color(
                    red: cos(phi).magnitude,
                    green: cos(theta).magnitude, 
                    blue: sin(phi).magnitude
                 )
                 .translateBy(Vector(x: x, y: y, z: z))
             }
        }
    }
}

Adding sketch to a command

The sketches can be rendered out to file like so:

let layerStage = RandomShell().buildStage()

let usdabuilder = USDAFileBuilder()
let path_usd = "shell_\(FileIO.timeStamp()).usd"
FileIO.writeToFile(string:usdabuilder.generateStringForStage(stage:layerStage), filePath: path_usd)

let x3dbuilder = X3DFileBuilder()
let path_x3d = "shell_\(FileIO.timeStamp()).x3d"
FileIO.writeToFile(string:x3dbuilder.generateStringForStage(stage:layerStage), filePath: path_x3d)

There is a template parsable command to make extending the CLI easier: template.swift

Upcoming Roadmap

• rewrite to allow for multiple primitive types
• update tests to reflect refactor
• add cube type
• [] add additional tests
• [] add optional "USDServiceProvider" to check files / make crates for importing into other Swift projects.
• [] fix adding colors / materials (X3D has color function not currently using)
• [] add additional primitives
• [] make an "Assembly" or other group type
• [] make an "over"
• [] add meshes
• [] add camera
• [] add animation