THE MOHPA EMITTER TOOL.

 

A BASIC INTRODUCTION

 

By Joshua Prigg

 

To access the emitter tool, just bring up the console and enter �pushmenu emitter2�

 

The emitter tool allows you to easily create particle effects for MOHPA. I only say �easy� because it allows you to work in real time as apposed to using 3rd party software such as Max or Maya. The Emitter Tool may seem complex, but after some experimentation and practice, you will be blowing stuff up in no time.�

 

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MODEL

 

  1. From here, you can call the model or material that you will be using for your effect. All materials in MOHPA are in:

 

MOHPA\Game\main\materials

 

As long as your MOD mirrors this directory, you will be able to access your materials in the FX editor as well all the pre-made materials.� In MOHPA, materials are labeled as XMAT�s. The FX editor sees these XMAT�s as �sprites�.� So if you were to use say �fire1.xmat� you would type in �fire1.spr� as your model.

 

  1. If you actual click on the model button, a menu will appear giving you a list from the model directory. You will only use this if you wish to involve Granny files in your effect. Unfortunately, you can�t use this to browse materials.

 

PARTICLE LIFE

 

  1. This controls the life span for the effect. There are two sets of numbers that control the variables. From example. If you wanted an effect to last about two seconds, you would just enter:

 

�2.0 and 0.0

 

2.�� If you wanted the effect to last about 5-10 seconds, then you would enter:

 

5.0 and 10.0

thus the effect will randomly die anytime after 5 seconds, but may last up to 10 seconds

 

You can also add a �delay� to the effect.� If you enter 2.0, then effect will wait about 2� seconds before spawning in.�

 

PARTICLE EMISSION

 

1.      �Spawn Count� controls the amount of particles per emission. It is used for single shot effects such as explosions, puffs, anything thing that involves a single event.

 

2.      �Emit Rate� controls and rate from which particles are emitted. Basically, it�s like the gas pedal for your effect. This is only used if you have an effect that is constant. Such as a waterfall, or a pillar of flames. The higher the number and faster particles enter the scene.

�Cull Dist� controls the distance from which an effect enters the scene. As well as the distance from which the effect exit�s the scene. You will want to use this for conserving particles. Basically, you don�t want an emitter running if the player can�t see it.

A good rule of thumb is to use you farplane distance. Lets say that in the world spawn values, the farplane is set to 3000. So if I set the �cull dist� to 0.0 and 3000. The effect will die off once it passes the farplane.

 

VERTEX COLOR

 

1.      Here you can control the RGB values for the effect as well as the alpha channel. I would only used this to make adjustments. Your color values should mainly be dependent on the sprite.

 

 

 

 

 

 

SCALE

 

  1. This tab pretty much controls the size of each particle based on XY axis or using the UV�s of the image.
  2. �Scale� controls the original �size� of each particle. If the number is set to 2.0, then the particle will be twice as big than it�s original size.
  3. �Scale Rate� Controls the growth rate a particle. If the life we�re set to 5.0 and �scale rate� was set to 1.0�, then you will see the particle gradually grow through out the 5 seconds.

 

 

 

 

MOTION1

 

  1. This tab controls the motion that you want to give the effect.
  2. �Angles� is used the control the orientation of the particle using 0-360. So if I use 45 and 90 for the x-axis. Then every time the particle appears, if will randomly be turned 45-90 degrees on the x-axis.
  3. �Random Vel� controls the direction of the movement. The higher the number, the faster the particles will go.�
  4. �Org Offset and Axis Offset� are used to offset the position of where the particle is emitted. An example of how this can be used to set:

 

x-axis to �500 and 1000.

y-axis to �500 and 1000.

 

Every time the particle is emitted it will randomly appear along both the x and y axis.

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MOTION2

 

  1. �Motion2� is used to more generalize movement. If �circle� was selected, than the particles emit in a circular formation. This is only really noticeable if you have a higher spawn count or emit rate.
  2. �Collision� is used if you want particles to be affected by geometry. Thus causing a collision. Use this sparingly, because it very expensive.
  3. �Die touch� is used to create a death state for an effect. If �collision�, is selected, and I choose a �deathmodel� you can actually choose another effect to react from a collision. An example of this would be if I made a fireball effect and launched it in the air. Eventually it would collide with the ground. As soon as it hits the ground, the �deathmodel� or an explosion effect would spawn in. This option is also expensive, so use it sparingly.

 

 

 

RENDER

 

1.      �Effects� is used to control blur, noise and fade. When using �fade� there are two parameters.

�Fade in� tells the particle to gradually go from transparent to visible.

�Fade dly� tells the particle to gradually go from visible to transparent�

 

The fade number can�t be larger than the life span. An example of using this would be:

The life is 5.0, the �fade in� is 1.0 and the �fade dly� is 3.0. Thus, after 1 second, the particle will gradually become visible, and than after 3 seconds the effect would fade out again. If the time involved in the fade exceeds 5 seconds, then it just won�t work.

 

2.      �UV Scroll� is used if you want to scroll a sprite (the image you have chosen to represent the particle.) This should only be used if you are using a tillable image, otherwise you will see seams within the sprite.

3.      �Animated Textures� is used for animated sprites. You can either play the sequence or lock onto a specific frame.

4.      �Sprite Orientation� by default is set to �parallel oriented�. This means that image will always be parallel to the player. Other settings with in this menu can the change the orientation if needed.

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STAGES

 

1. In this tab, you can create new stages for effects as well as cycle through them. Most effects are made up of multiple stages. For each sprite that you use, requires a new stage. When previewing single shot effects, you will see each stage play simultaneously. When viewing consistent emitters, you can only view one stage at a time.

 

 

 

EMITTER

 

1.      �Place emitter� will allow you to do just that. Clicking this will cause a red arrow to appear at your current position. This arrow represents the effects origin.

2.      �Emitter mode� is used to set the type of effect. The two which you are more likely to use are:

 

��SFX mode�, for single shot effects

 

�Emitter Mode�, for a consistent emitter

 

3.      �Emitter model� is used if you wish to add an effect to a model. From here you can browse the model directory and load one. The placement of the effect is based on a �spawn tag�. This is basically just the joint of a model. If you created a model, and added a joint called �fire1�, then it will appear under �spawn tag� when the model is loaded.

4.      �Files� is used for saving and loaded you effects. The information for the effect is saved out in text file in:

My Documents\EA Games\Medal of Honor Pacific Assault(tm)\dump\

 

5.� The �Trigger Effect� button is the magic maker. You will use this to preview effects in SFX mode.