February 13, 2019
Tower Defense Tutorial
Episode 14 – Laser Beamer
Youtube – How to make a Tower Defense Game (E14 LASER BEAMER) – Unity Tutorial
By: Brackeys
Ep. 14
This tutorial creates the Laser Beamer, yes beamer, object prefab. Something I’ve done when importing these to make it more similar to the tutorial, under the Materials tab for this imported model, I use “Extract Materials” to make sure all of the materials become easily available to alter and move around in the Unity editor. Before making it into a prefab, we did the same steps we did with the other turrets: add partToRotate empty object, add firePoint empty object, child turret head and firepoint to partToRotate empty so they rotate properly/easily with a forward facing z-axis object.
Everything else was also updated similarly to the other turrets. We added another TurretBluePrint public class to the Shop script so we can inform it of the new prefab to use for the LaserBeamer and its cost. We then added the LaserBeamer shop button (sprite image on UI) and added its new click event for selecting the LaserBeamer.
The laser beamer is different in that its projectile will use a Line Renderer component to simulate a laster. This has clearly received a lot of updates over the several iterations of Unity between now and this tutorial. The “Positions” section has more of a table setup. The “Width” parameter section is now actually a small line graph instead of just values (assuming this allows for more variation with curves, etc.).
The line renderer material gave me some issues, which I cover in PROBLEMS below. However, it seems the material I chose doesn’t allow for variation of the alpha value in the line renderer color component. Another difference here is the suggested shader for the line renderer material was “Particles – Alpha Blended”, which no longer exists. I used “Particles – Standard Unlit” which worked for me. The colors are also different now. Instead of just a start and end color option, it is now a full gradient preview bar with colors on the bottom and alpha values on the top.
Then we edited the Turret script to deal with this new type of weapon. We separated out the variable headers from Attributes into General, Use Bullets (default), and Use Laser to keep everything organized. Then we moved on to dealing with the line renderer in a method, Laser.
We started scripting the line renderer by setting its positions (values in its position array that determine the points to connect with a line). Since we only have two points, those are the start and end point of our line. It’s as easy as: lineRenderer.SetPosition(0, firePoint.position);lineRenderer.SetPosition(1, target.position);Where the first input in SetPosition is the element number in the position array of the line renderer, and the second input is what that position is. So this example draws a line between our firePoint (shooting location) and whatever the target is.
Our laser worked, but it would stay in its last position if the target moved out of range (since it no longer needed to update its location). Since we already had a return happening for the check when there is no target, we just added a laser specific check to also enable = false for the line renderer when there is no target.
PROBLEM
SOLVED: My line renderer was not displaying properly after applying a basic material to it in the prefab editor (it was just solid black, when the material was white). At first I thought this was a lighting issue in the new prefab editor, so I found out that you can create a scene to use as the prefab editor scene and add it in your Project Settings. So I did that and it was still black, but I noticed if I rotate around it was white for about 180 degrees of viewing rotation. I then noticed the next part of the tutorial mentioned changing the shader for the material, and this directly solved the issue. Line renderers might deal with materials strangely, and may often use non-default shaders.
BONUS OBJECTIVES
Add particle effect to the end of the laser line renderer for that sparking impact effect a lot of lasers have.
To set up the Turret variables/editor even better, have a variable called UseBullets, or an enumerator to select either Bullets or Laser, then show fields depending on what you selected. Create an editor script for this. Look up “Unity Custom Editor”.
SUMMARY
- When importing models, use “Extract Materials” to specifically pull out all of the materials to make them easier to edit.
- Check the shader for the material you apply to line renderers since they seem to act uniquely
- Look into “Unity Custom Editor” to learn about editor scripts