KCSG

KCSG is a Kotlin Multiplatform constructive solid geometry library with a first-class Kotlin DSL. Originally forked from JCSG, it has been substantially reimagined — the DSL is the primary interface, boolean operations compose naturally with Kotlin operators, and it runs on JVM, JS, WASM, Native, and every Apple platform. KCSG is the geometry engine behind Konstructor.

Example

val sensor by csg {
    val sensorTall = roundedCube {
        dimensions = xyz(sensorWidth, sensorLength, sensorHeight * 2)
        cornerRadius = corners
    }
    val sensorBounds = cube {
        dimensions = xyz(sensorWidth, sensorLength, sensorHeight)
    }
    sensorTall and sensorBounds
}

val base by csg {
    val block = cube {
        dimensions = xyz(baseWidth, baseLength, baseHeight)
    }
    block - positionedSensor - xCyl - yCyl
}

Primitives like cube, sphere, cylinder, and roundedCube are built with type-safe builders. Combine them with and (intersection), - (difference), and or (union), or use the operator equivalents *, -, and +. Transforms chain via translate, rot, and scale.

Setup

KCSG is published on Maven Central as com.monkopedia:kcsg and com.monkopedia:kcsg-dsl.

// build.gradle.kts
dependencies {
    implementation("com.monkopedia:kcsg:0.4.0")
    implementation("com.monkopedia:kcsg-dsl:0.4.0")
}

For Kotlin Multiplatform projects, add the dependencies in commonMain and Gradle will resolve the appropriate platform artifact.

Command Line Tool

KCSG includes csgs, a standalone command line tool that runs .csgs script files and generates STL or OBJ output directly — no Kotlin project required. The fat jar is attached to each GitHub release.

java -jar csgs-all-0.4.0.jar sensor.csgs -e base -o out/

This makes KCSG usable as a scripting environment for 3D modeling. Write geometry in the DSL, run it from the command line, and get mesh output.

License

Apache License 2.0. See LICENSE.txt.

Acknowledgments

• Michael Hoffer for creating JCSG
• Evan Wallace for csg.js, the original JavaScript CSG implementation