## Tuesday, November 8, 2016

### Andrew DiNunzio - 10/31/16-11/7/16

This week I spent time concepting and implementing some of the aforementioned whip mechanics.

I figured out some more of the math that would be involved, as shown:

I then considered how I could apply drag to the ball in a way to make the spline length approach a certain number. Thanks to the Math Stack Exchange site, I found this function I could use:

Unreal Engine has a "Linear Damping" functionality which reduces the velocity  of an object on each tick of the game. I subtracted the function above from 1 to get how much to reduce the object's velocity by. This worked very well, but it still needs a lot of work.

I implemented this Resistance to Stretch, as shown below:

Additionally, I wrote out how I might figure out which direction to apply a force for Resistance to Bending dynamically. I figured out a way to figure out the direction by taking multiple partial derivatives of an ellipsoidal function. I made the assumption that two of the dimensions of the ellipsoid would be the same (the one along the ray-cast of the motion controller being the one that is different). Given the length of the spline as being the desired endpoint, I was able to calculate what the ellipsoid would be, and thus what direction to apply the force by taking the derivatives, by calculating the following:

My next step is to implement this as a force, combined with a drag similar to the Resistance to Stretching force, preferably in C++ if possible to avoid frame drops.

Time spent: Total: ~15 hours

• 2 hours - Working out math for Resistance to Stretching, Resistance to Bending, and Drag
• 8 hours - Implementing Stretching Force
• 2 hours - Platform size reduction
• 3 hours - GDD work

Pros:

• Our gravity beam feels much better
• Almost all of the "difficult" things are programmed (even if they aren't working perfectly). AI is the last one to implement.
Cons:
• Code for gravity beam is tightly coupled to the MotionControllerPawn
• Multiple branches in VCS, which doesn't work well with binary UE assets
• Whip mechanics still need a lot of work - feels like throwing a balloon with a pool noodle, when it should be thrown with much more force.