scala simple scenegraph

example

val hexapod = new AssemblyNode {
  transform.scale(0.1f, 0.1f, 0.1f)

  // Body
  children += new AssemblyNode {
    children += new ModelNode(assets.get("assets/Base.obj"))
  }

  // Legs
  (1 to 6).foreach(i => {
    children += new AssemblyNode {
      transform.rotate(0.0f, 1.0f, 0.0f, i * 60.0f)
      children += new ModelNode(assets.get("assets/Leg v30.obj"))
    }
  })
}

source

class RenderContext {
  val modelBatch = new ModelBatch
  val environment = new Environment

  val worldTransform = new Matrix4

  def render(cam: Camera, node: Node) = {
    worldTransform.idt
    modelBatch.begin(cam)
    node.traverse(this)
    modelBatch.end
  }
}

abstract class Node {
  def traverse(ctx: RenderContext): Unit
  val children = new ArrayBuffer[Node]
}

class AssemblyNode extends Node {
  val transform = new Matrix4

  def traverse(ctx: RenderContext) = {
    val oldTransform = new Matrix4(ctx.worldTransform)

    ctx.worldTransform.mul(transform)
    children.foreach(_.traverse(ctx))
    ctx.worldTransform.set(oldTransform)
  }
}

class ModelNode(model: Model) extends Node {
  val instance = new ModelInstance(model)
  def traverse(ctx: RenderContext) = {
    instance.transform.set(ctx.worldTransform)
    ctx.modelBatch.render(instance, ctx.environment)
  }
}