Transform Vector3f by Matrix4f

Contribution Depot
1

Rather important and useful method I threw together. Tested and working. Should be added to Matrix4f.java

Please add to the engine so that I don’t have to keep using my custom build.



[java]

/**

*

  • <code>transformVect</code> transforms a given Vector3f by this matrix

    *

    *
  • @param vec
  •        the Vector3f to be rotated.<br />

*/

public void transformVect(Vector3f vec){

Vector3f tmp = new Vector3f();



tmp.x = (vec.x * m00) + (vec.y * m01) + (vec.z * m02) + m03;

tmp.y = (vec.x * m10) + (vec.y * m11) + (vec.z * m12) + m13;

tmp.z = (vec.x * m20) + (vec.y * m21) + (vec.z * m22) + m23;

vec.x = tmp.x;

vec.y = tmp.y;

vec.z = tmp.z;

}[/java]

2

Yeah, you are right. I didnt remember transforming and multiplying were the same thing… Could you add this method anyway? as lots of bullet math uses “transform” instead of multiply.

3

No, we won’t have two methods that do the same thing with different names, what’s wrong with “mult”?

4

Generally, from what I have read about vector/matrix math and what I have learned in school, it has been referred to as transforming.

5

No… that’s not right. You can use a matrix to transform points by multiplication IF (and only if) that matrix is a transformation matrix.



There are any of a hundred reasons to use a matrix that are not transformations. Multiplying is the correct term. You are just using it for transforming.

6

Or…we don’t, and you use the Matrix4f.mult(Vector3f vec, Vector3f store) method :wink:

7

Okay, thanks for clearing that up :slight_smile: