loos::XForm Class Reference

Matrix class for handling coordinate transforms... More...

#include <XForm.hpp>

Public Member Functions
	XForm (const GMatrix &m)
	Initialize an XForm with an existing matrix.
	XForm (const XForm &x)
void	push (void)
	Push the current matrix onto the stack.
void	pop (void)
	Pop the top matrix off the stack.
void	load (const GMatrix &)
	Load a matrix onto the current transform.
void	concat (const GMatrix &)
	Concatenate (post-multiply) a matrix with the current transform.
void	premult (const GMatrix &)
	Premultiply the current transform.
void	identity (void)
	Set the current transform to the identity.
bool	unset (void) const
void	translate (const greal, const greal, const greal)
	Translation matrix.
void	translate (const GCoord &)
	Translation specified by a GCoord()
void	scale (const greal, const greal, const greal)
	Scaling.
void	scale (const GCoord &)
	Scaling.
void	rotate (const GCoord &, const greal)
void	rotate (const char, const greal)
GCoord	transform (const GCoord &)
	Transform a GCoord() with the current transformation.
GMatrix	current (void) const
	Get the current trasnformation.

Detailed Description

Matrix class for handling coordinate transforms...

This is based on the OpenGL/RenderMan model of handling geometric transforms. Coords are expected to be homegenous and the transformation matrix is 4x4. Rotations are all left-handed.

The transform mantains a stack of transformation matrices that you can push and pop as necessary. You can also load the current transformation with an arbitrary matrix.

Transformations are concatenated by post-multiplication. This means the last declared transformation is the first one applied to an atom's coordinates... Imagine you've defined a set of transformations in your code:

*
*  rotate       ->  M_r
*  translate    ->  M_t
*  scale        ->  M_s
* 

These are post-multiplied together to create the composite transformation matrix:

*  M = M_r * M_t * M_s
* 

Now, when you transform your coordinate vector, it's just the matrix-vector multiplication:

*   v' = Mv = M_r * M_t * M_s * v
*  

So from the perspective of the atom's coordinate frame, we're scaled, then translated, then rotated into the global coordinates...

Member Function Documentation

rotate() [1/2]

void loos::XForm::rotate	(	const char	axis,
		const greal	angle )

Rotate about a specified axis Axis is given by either 'x', 'y', or 'z'. Angles are in degrees.

rotate() [2/2]

void loos::XForm::rotate	(	const GCoord &	ov,
		const greal	angle )

Rotate about an arbitrary vector Angles are specified in degrees.

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The documentation for this class was generated from the following files:

• src/XForm.hpp
• src/XForm.cpp