# Understanding the tutorial components

This tutorial shows you how to set up a simulated slag foundry that is composed of the following components:

## nParticle objects

You create a total of three nParticle systems to simulate the slag foundry scene. All three systems are controlled by the same Nucleus solver node. The first nParticle system (nParticle_slag) added to the scene simulates the slag that flows down the chute. You convert this Ball style nParticle object to an nParticle output mesh then shade and texture it with a fractal texture. The assigned texture gives the output mesh the appearance of molten metal when rendered. You create, adjust, and shade the nParticle_slag and output mesh objects, in Lesson 1. See Lesson 1 Creating the molten slag.

The remaining two nParticle systems simulate the metal sparks that fly off the slag flow. To generate the sparks, you create a two-stage effect that is initiated by a particle collision event. The nParticle_slag object that you create in Lesson 1 acts as the source particle system for the collision event.

After the resulting target particle system (nParticle_sparks_emitter) is generated by the event, it becomes a surface emitter for the nParticle sparks (nParticle_sparks). To create the look and streaking behavior of the sparks, you use the Tube (s/w) particle render type. The two-stage sparks effect is created in Lesson 3. See Lesson 3 Creating flying sparks.

## nParticle output mesh

An nParticle output mesh is generated from the nParticle_slag object. This mesh is the visible slag that flows down the chute into the tub. It is also used as a surface emitter for a 3D fluid. The fluid effect creates the smoke that rises above the molten slag as it slides down the slag chute into the tub. The output mesh is textured with a 2D fractal texture to give it the orange glow of molten metal when the scene is rendered. The mesh is created and adjusted in Lesson 1. See Lesson 1 Creating the molten slag.

## 3D fluid effect

The 3D fluid is emitted into the scene from the surface of the nParticle output mesh. It simulates the smoke and steam that rises from the molten slag as flows down the chute. The fluid container uses Fluid Auto Resize so that it can follow the slag while maintaining a manageable container size. The fluid is created in Lesson 2. See Lesson 2 Creating the slag smoke.

## External gravity field

You apply an external Gravity field to the nParticle_Sparks object to create the arcing behavior of the sparks as they fly off the slag. Also, to create realistic spark behavior, you will simulate with Ignore Solver Gravity turned on. The gravity field is added to the scene in Lesson 3. See Lesson 3 Creating flying sparks.

## Non-dynamic objects

Lights, a camera, and render settings are added to the scene so that you can render out a frame or part of a sequence at various stages of the tutorial.

## Tutorial workflow

The scene files for each lesson let you complete specific aspects of the tutorial. You can start the tutorial using the scene file for Lesson 1 and continue to add the tutorial components until you complete all four lessons. Otherwise, each lesson can be completed separately using the following scene files:

- For Lesson 1: Creating the molten slag, use SlagPourFoundry_1.mb
- For Lesson 2: Creating the slag smoke, use SlagPourFoundry_2.mb
- For Lesson 3: Creating flying sparks, use SlagPourFoundry_3.mb
- For Beyond the tutorial, use SlagPourFoundry_4.mb

To watch a video of the rendered simulation, open SlagPourFoundryFinal.mp4v, included with the tutorial lesson files.