Shot 4 Full Render Preview

Shot 4 is by FAR the most complicated shot I've worked on so far. I wanted to try some creative solutions for some pretty difficult effects to pull off and I really like how they came out! While this version does have the casualty counter, the release on the Patreon will not. There will be a second version that you can download with this counter upon release.

There is one small issue with flickering volumes that I need to fix before I call this shot done, but this is the look overall!

Custom Projectiles in Houdini

This shot called for projectiles to be hitting Legacy's body and detonate, causing the shield impact effect you saw in part 1. This was a combination of 3 different techniques that I had to work backwards to achieve.

The first step was something I talked about in WIP #4 of Judgement Day (Part 2). Using the pyro burst source on a set of points across Legacy's body over a set time period allows me to create explosions exactly where each missile hits. The randomization of each explosion's start frame is done through an attribute adjust float where I can define the first start frame and the range of frames for all the explosions.

One important note is that each explosion has to be instanced on a point attached to Legacy's model. You can use point deform for this, but I would actually recommend using primitive UVs and the xyzdist function for this.

In Houdini, each primitive (polygon) has a UV coordinate. This UV coordinate is unchanging and it means you can pull precise values of attributes off of the primitive. In this case, I'm pulling the positional values from each primitive on Legacy's body and interpolating the points onto that position using xyzdist.

Let's talk about how we can use the "startframe" attribute to drive the shield effect! If you want to see how I used a geo solver to create the effect, you can go to this WIP here. The basic idea is that if the frame doesn't equal the startframe value, no geometry will spawn.

Now things are going to get technical. Creating custom projectile paths is not an easy thing to do, but by using linear interpolation, it becomes a bit easier. To summarize the code VEX code below, I'm using linear interpolation to move each point between a start and end position over time. The last position is "endP" and the first position is "startP" and each point moves over time "t".

This however, only creates a straight line. I wanted to add an arc to the path, so simply multiplying pi times time "t" allowed me to arch each point. If you want to use the code above, all you need are two different point systems with IDENTICAL point counts.

One final piece of the puzzle is making sure the orientations are correct for each point. I thought of hard coding this into the script... but then I realized I could just a point velocity node. This calculates the velocity for each point as it travels through space. I then just converted the "v" attribute to my normal "n" attribute and that solved the alignment issue.

Particle Trails

This deserves it's own section simply because it's a pretty cool method for creating trails behind geo. In Houdini, there is a node called the "particle trail" node. This node creates 3D spline trails behind particles.

One issue that I had with these trails, though, was that they were sticking around after the point had reached its destination. To fix this, I used the "startframe" attribute that each trail inherited. This resulted in each point being nicely deleted after the point had reached its final position.

Gaea

I love heightfields in Houdini. They are great! But I wanted to try something new this time around and use the industry standard terrain generation software, Gaea! I purchased a full license from them as well as their $100 one-time payment is hard to beat.

Gaea is kinda like Houdini in the way that it function: it's node based. Node trees might look a little similar to what I've shown in the past, but Gaea's terrain nodes are a bit more robust.

I'm not going to go over the terrain generation itself this time around as this terrain was relatively simple to set up. I do plan to do more complex terrains in the future, though, which I absolutely will go over. I do want to talk about how Gaea handles textures, though.

Gaea uses something called a "satmap" for textures. These "satmaps" are color sampling schemes that are based on real world geometric data. This allows for complex

colored terrains with relatively low effort.

For these satmaps to work, you'll need a texture base. This automatically calculates masks that the satmap uses to color the geometry, such as the slopes, soil, and peaks.

Additionally, Gaea offers some pretty convenient meshing options. One of the meshing features is exporting dynamic topology, where Gaea will increase the polygon density where more details in the terrain are. This will HEAVILY help save on memory, especially when it comes to larger terrains.

Overall, the Gaea feels a lot more robust than what I've been doing with Houdini. I'm quite happy with the way it works with it allowing for exceptionally fast iteration.

And that's all for this WIP! I'll have another WIP up next week for Micro Management. Thank you all for your patience on this! <3