Wednesday, November 19, 2014

Unreal Engine 4 Dev Update #3: Smooth Zoom Functionality for Top Down Template

In my first UE4 dev update, I had written about adding a basic Zoom functionality for the Top Down template in UE4 using Blueprints. But as I had mentioned back then, I had implemented a step-by-step zoom system. You could only zoom in discrete steps depending on how many times the input button was clicked. Well that might be useful in certain cases, but I wanted to add a Smooth Zoom functionality to my game. So I went about making some changes to the earlier Blueprint. Most of the stuff remains the same, so changing to this newer version will hardly take a couple of minutes. As a result, I won't be writing much about the stuff that I had already explained in the first post. For reference, you can find it here:

Unreal Engine 4 Dev Update #1: Zoom Functionality for Top Down Template

Moving on, let's get to the topic at hand.

So basically, in my earlier post, I had made changes of 100 units to the 'Target Arm Length' of the player character's 'Spring Arm' component. In order to implement Smooth Zoom, I added a Timeline node. They allow you to make simple time-based animations. For learning more about Timelines, you can check out the official documentation here:

Unreal Engine 4 Documentation : Timelines

Alternatively, you can check out this Youtube tutorial:

Unreal Engine 4 Blueprint QuickShot - 7 - Changing Things Over Time

After adding a Timeline node, this is what my Blueprint looks like:

As you can see, instead of making discrete changes of 100 units each, I'm changing it continuously by units of 10, relative to the graph in the Timeline Node. Since I wanted the zoom to start out slow and then speed up, I've made a linear graph with respect to time. Here's a screenshot of the Timeline Node itself:

I have two key values in there: 0 at time t=0 and 10 at time t=10. I'm using the same values for both the Zoom In as well as Zoom Out Timeline. For now, I've kept the range to 10 seconds, but it hardly ever reaches that point, since I have a clamp in my Blueprint to restrict the maximum and minimum zoom. So I'll probably reduce the range to 5 seconds soon. Also I made sure that the Timeline execution always start from the beginning of the graph at each button press, by connecting to the 'PlayfromStart' input pin.

And that's it. We have implemented a simple Smooth Zoom functionality. You can see this in action in the following video:

If you're interested in seeing more of my work in Unreal Engine 4, you can check out my Youtube channel as I usually update the videos there before posting updates here:
And that's all for now. Next update on implementing Camera Rotation for the Top Down template, coming soon. Signing out.