• Products
  • Solutions
  • Made with Unity
  • Learning
  • Support & Services
  • Community
  • Asset Store
  • Get Unity

UNITY ACCOUNT

You need a Unity Account to shop in the Online and Asset Stores, participate in the Unity Community and manage your license portfolio. Login Create account
  • Blog
  • Forums
  • Answers
  • Evangelists
  • User Groups
  • Beta Program
  • Advisory Panel

Navigation

  • Home
  • Products
  • Solutions
  • Made with Unity
  • Learning
  • Support & Services
  • Community
    • Blog
    • Forums
    • Answers
    • Evangelists
    • User Groups
    • Beta Program
    • Advisory Panel

Unity account

You need a Unity Account to shop in the Online and Asset Stores, participate in the Unity Community and manage your license portfolio. Login Create account

Language

  • Chinese
  • Spanish
  • Japanese
  • Korean
  • Portuguese
  • Ask a question
  • Spaces
    • Default
    • Help Room
    • META
    • Moderators
    • Topics
    • Questions
    • Users
    • Badges
  • Home /
avatar image
0
Question by greenshadow · May 03, 2013 at 04:06 AM · rotationvectorrelative

Rotate a Vector Relative to Another Vector

I'm making a runner game which scrolls forward on the z-axis. When the player clicks on a target, a projectile called bolt is fired at the enemy position. I want to have a Spread powerup (similar to Spread seen in the old Contra games), where a second bolt is fired at an angle relative to the target vector.

The problem I am having is that the second bolt ends up firing almost a mirror image (flipped on the x-axis) from where the target is when I shoot to the right, and not accurately when I shoot to the left. How can I make this work properly? Here is my existing code, in the handler for the bolt object:

 //Move bolt towards enemy
 float time = 0.5f;
 float t = 0f;
 Vector3 startPos = Runner.runnerPosition;
 Vector3 newPos = enemyScript.enemyPosition;
 newPos.z += enemyScript.speed * time;
 
 //***This line of code is not working as intended***
 Vector3 spreadPos = Quaternion.AngleAxis(-5f, Vector3.up) * newPos;
 
 switch (this.gameObject.tag)
 {
     case "FiredBolt":
         while (t < 1.0f){
             t += Time.deltaTime / time; // Sweeps from 0 to 1 in time seconds
             if (bolt != null) {
                 bolt.position = Vector3.Lerp(startPos, newPos, t);
             }
             yield return 0;
         }
         Destroy(GameObject.FindGameObjectWithTag("FiredBolt"));
     break;
     
     case "SpreadBolt":
         while (t < 1.0f) {
             t += Time.deltaTime / time; // Sweeps from 0 to 1 in time seconds
             if (bolt != null) {
                 bolt.position = Vector3.Lerp(startPos, spreadPos, t);
             }
             yield return 0;
         }
         Destroy(GameObject.FindGameObjectWithTag("SpreadBolt"));
     break;
 }
Comment
Add comment
10 |3000 characters needed characters left characters exceeded
▼
  • Viewable by all users
  • Viewable by moderators
  • Viewable by moderators and the original poster
  • Advanced visibility
Viewable by all users

1 Reply

· Add your reply
  • Sort: 
avatar image
0
Best Answer

Answer by robertbu · May 03, 2013 at 04:32 AM

I think you are looking for something like this:

 Vector3 spreadPos = startPos + Quaternion.AngleAxis(-5f, Vector3.up) * (newPos - startPos);

Your current code rotates the vector based on the world origin. In order to get the spread, you want to rotate it from the point the bolt is shot.

Comment
Add comment · Show 1 · Share
10 |3000 characters needed characters left characters exceeded
▼
  • Viewable by all users
  • Viewable by moderators
  • Viewable by moderators and the original poster
  • Advanced visibility
Viewable by all users
avatar image greenshadow · May 03, 2013 at 04:36 AM 0
Share

You have nailed it. Thank you sir.

Your answer

Hint: You can notify a user about this post by typing @username

Up to 2 attachments (including images) can be used with a maximum of 524.3 kB each and 1.0 MB total.

Welcome to Unity Answers

If you’re new to Unity Answers, please check our User Guide to help you navigate through our website and refer to our FAQ for more information.

Before posting, make sure to check out our Knowledge Base for commonly asked Unity questions.

Check our Moderator Guidelines if you’re a new moderator and want to work together in an effort to improve Unity Answers and support our users.

Follow this Question

Answers Answers and Comments

12 People are following this question.

avatar image avatar image avatar image avatar image avatar image avatar image avatar image avatar image avatar image avatar image avatar image avatar image

Related Questions

Imported model is rotated 90 degrees off of straight, can't use any transforms 1 Answer

Rotating a direction Vector3 by Quaternion 2 Answers

rotation of child object inside another simultaneously rotated object 1 Answer

How to keep local rotation when using raycasts? 1 Answer

Efficiency of transform.forward, up, and right 2 Answers


Enterprise
Social Q&A

Social
Subscribe on YouTube social-youtube Follow on LinkedIn social-linkedin Follow on Twitter social-twitter Follow on Facebook social-facebook Follow on Instagram social-instagram

Footer

  • Purchase
    • Products
    • Subscription
    • Asset Store
    • Unity Gear
    • Resellers
  • Education
    • Students
    • Educators
    • Certification
    • Learn
    • Center of Excellence
  • Download
    • Unity
    • Beta Program
  • Unity Labs
    • Labs
    • Publications
  • Resources
    • Learn platform
    • Community
    • Documentation
    • Unity QA
    • FAQ
    • Services Status
    • Connect
  • About Unity
    • About Us
    • Blog
    • Events
    • Careers
    • Contact
    • Press
    • Partners
    • Affiliates
    • Security
Copyright © 2020 Unity Technologies
  • Legal
  • Privacy Policy
  • Cookies
  • Do Not Sell My Personal Information
  • Cookies Settings
"Unity", Unity logos, and other Unity trademarks are trademarks or registered trademarks of Unity Technologies or its affiliates in the U.S. and elsewhere (more info here). Other names or brands are trademarks of their respective owners.
  • Anonymous
  • Sign in
  • Create
  • Ask a question
  • Spaces
  • Default
  • Help Room
  • META
  • Moderators
  • Explore
  • Topics
  • Questions
  • Users
  • Badges