Matrix4

Files:	Matrix4.h, Matrix4.C
Derived from:	none
Global instance (if any):	none
Used in optional component:	Part of main VMD code

Description

A 4 by 4 matrix of floats, used primarily for the transformation matrix of Displayable and DisplayDevice objects. Along with general routines to rotate, translate, and scale the matrix, this also contains overloaded operators for = (copy, either a matrix or a scalar), *= (multiply, by either a matrix or a scalar), and += (add a matrix).

There are many functions in this class to simply add or multiply the matrix, to take the inverse of the matrix, or to apply rotations, translations, etc. Most importantly, functions exist to take a 3- or 4-vector, and multiply (transform) it by this matrix.

Constructors

• Matrix4::Matrix4(void) - creates a 4 by 4 identity matrix.

• Matrix4::Matrix4(float) - creates a 4 by 4 matrix with all elements set to the given constant.

• Matrix4::Matrix4(float *) - creates a 4 by 4 matrix, copying the given array of 16 floats into the matrix (in row-major format).

• Matrix4::Matrix4(const Matrix&) - creates a 4 by 4 matrix identical to the matrix given.

Internal data structures

• float mat[4][4] - the matrix data itself.

Method of use

The many functions in this class are not listed here. The most common use of this is to maintain a transformation matrix for transforming 3D vectors from one coordinate space to another, i.e. to rotate, translate, and scale them. Once a 4 by 4 matrix `M' has been set up, then a vector `V' is tranformed and placed in the view vector `VT' as:

M.multpoint3d(V, VT)