So we’ve got a new particle system to play, let’s see what it does!
Particles that we allowed to change right now include special weapons effect, like Bounty Hunter Jinada glow, Anti-Mage glowing weapon that replaced vibrating lightning and Phatom Assasins golden glow. Let’s review what Valve told us!
For items which have effects on them by default, such as edge glows, item authors will be required to submit a .dmx or .fbx mesh which defines where these particles should go on their item. This will use base effect authored for the item and place the particles accordingly.
To do this, create a new mesh, much like creating an LOD. However, this mesh will represent particle positions, one per vertex. Triangles, faces, and general connectivity do not matter on this mesh. The best way to create a mesh for this is to treat it as a single polygon. Keep in mind that particles will be created from all vertices in the mesh, so do not attempt to create valid convex or closed triangles in the traditional sense if this creates vertices in undesired locations.
While it is possible to use the vertices from the original mesh, generally speaking the density will not end up being appropriate for the effect. In addition, UV’s, hard edges, etc. can create duplicate vertices in some cases which is generally undesirable.
There is a hard limit to the particle count allowed for each item.
While each piece of modeling software will vary, here is an example of how to quickly create effects for an item in Maya :
First, start with your finished geometry. Select this mesh and Modify->Make Live. This will allow us to use the base mesh to draw vertices for our new mesh, while constraining them to the topology of the original.
Next switch to the Mesh->Create Polygon Tool. This will allow you to draw the new FX mesh locked to the live geo. The entire mesh will be a single polygon. Draw points where you wish to see particles, such as along a blade edge. The density of these points will usually be higher than that of the normal mesh, it may require a bit of trial and error to get the proper density for the desired look.
Once you’ve added all the points, you can export just the effects mesh. Name your mesh the same as the item with a _fx postfix, similar to an LOD.
Loading the effect into the item submission tool will show you a preview.
WHAT THE FUCK AM I DOING?!
While this seems confusing at first, let’s take a look at the particle effects already ingame:
As you can see, in reality, particle “line” is actually a bunch of dots. Every “dot” is actually a vertex in this “particle mesh”, so let’s try creating one ourselves!
So following Valves advice, let’s get our weapon model, decide where we want our particles (on the edge) and we will use the “blade” edges for our particle mesh. Just select them, detach and skin the same way you skinned your weapon.
Export it, and load it up in the importer!
It works! Kind of.
As you can see, the effect is overwhelming, you can actually see the space between the particle dots, and there’s two rows of them! This happened because we grabbed the blade faces, but since it’s vertex-based particle effect, the vertices is all that matters! Because we grabbed the edge without any change, it repeats the wire and prodece the effect we don’t want. So let’s fix that! Getting back to our “particle mesh”, first, let’s add some more vertices on the edge! You can do this however you want, i just used Cut tool.
After adding some more vertices, let’s see how it looks ingame!
Great, now it’s smooth, seamless and looks almost great! It’s still overwhelmingand we still need to remove the second row that we left there. Let’s get into max and just delete them, right? Select them
Press delete, and bam!
Everything is gone D:
While our particle system is vertex based, it still needs some geometry too back it up (even if you managed to leave isolated vertices, it’ll give you error on import).
So what we want to do, is that we want to grab all the vertices we don’t need, weld them together so we can keep our vertices in one ugly polygon. Don’t worry if it looks bad, it’s only vertices that we care about.
Let’s test it ingame now:
Nice! We got rid of the second row and particle effect looks fine and dandy now! Remember that you can break it up all you want, skin them to any bone you like, get creative!
As a side note, if you’re creating the particle mesh from your geometry mesh, make sure to reset uv mapping, you can just drop planar UV map on it. This needs to be done in order to avoid vertex doubling on the uv shell edges.
You can check out finished submission here