The SGADE Documentation

the SGADE The Socrates Gameboy Advance Development Engine

The SGADE is a development library for the Nintendo Gameboy Advance. It's free for all uses and is distributed without guarantees. For more information visit the SGADE page.

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SoTransform

Structure to represent transforms. More...

Files

file  SoTransform.c
file  SoTransform.h

Data Structures

struct  SoTransform
 Transformation class definition. More...


Functions

void SoTransformMakeIdentity (SoTransform *a_This)
 Resets the transformation.

void SoTransformSetRotateX (SoTransform *a_This, s32 a_Angle)
 Sets the rotation angle around the X-axis.

void SoTransformSetRotateY (SoTransform *a_This, s32 a_Angle)
 Sets the rotation angle around the Y-axis.

void SoTransformSetRotateZ (SoTransform *a_This, s32 a_Angle)
 Sets the rotation angle around the Z-axis.

void SoTransformSetTranslation (SoTransform *a_This, sofixedpoint a_X, sofixedpoint a_Y, sofixedpoint a_Z)
 Sets the translational part of the transform.

void SoTransformRotateX (SoTransform *a_This, s32 a_Angle)
 Rotates the transform around the X-axis.

void SoTransformRotateY (SoTransform *a_This, s32 a_Angle)
 Rotates the transform around the Y-axis.

void SoTransformRotateZ (SoTransform *a_This, s32 a_Angle)
 Rotates the transform around the Z-axis.

void SoTransformTranslate (SoTransform *a_This, sofixedpoint a_X, sofixedpoint a_Y, sofixedpoint a_Z)
 Translates the transform.

void SoTransformToMatrix (SoTransform *a_This, SoMatrix *a_Matrix)
 Returns a 3 by 4 matrix representation of the transform.

void SoTransformToInverseMatrix (SoTransform *a_This, SoMatrix *a_Matrix)
 Returns a 3 by 4 matrix representation of the inverse of this transform.

void SoTransformSetScale (SoTransform *a_This, sofixedpoint a_ScaleX, sofixedpoint a_ScaleY, sofixedpoint a_ScaleZ)
 Sets the uniform scale value.

Detailed Description

Structure to represent transforms.

This module contains the definition of a transformation. A transformation can be represented by a matrix as well, but a matrix is more sensitive for accumulating errors, especially because we are using a low-precision fixed point format. That's why you should use this transformation class and not convert it to a matrix until the very last moment.

Note that the transform separately stores its translation, scaling, and rotation and they do not interact with each other. When constructing a matrix from a transform, we always composite them in the order X rotation, Y rotation, Z rotation, translation, scale. For this reason, transforms are not ideal for use in hierarchical scene graphs.

Function Documentation

void SoTransformMakeIdentity (  SoTransform *    a_This ) 
 

Resets the transformation.

Sets the transformation to the identity-transform. Sets the translation part to zero. Sets the rotational part to zero, and sets the uniform scale to one.

Parameters:
a_This  This pointer

void SoTransformRotateX (  SoTransform *    a_This,
s32    a_Angle
) 
 

Rotates the transform around the X-axis.

The difference between this one and SetTransformRotateX is that this one adds the angle to the existing angle.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformRotateY (  SoTransform *    a_This,
s32    a_Angle
) 
 

Rotates the transform around the Y-axis.

The difference between this one and SetTransformRotateY is that this one adds the angle to the existing angle.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformRotateZ (  SoTransform *    a_This,
s32    a_Angle
) 
 

Rotates the transform around the Z-axis.

The difference between this one and SetTransformRotateZ is that this one adds the angle to the existing angle.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformSetRotateX (  SoTransform *    a_This,
s32    a_Angle
) 
 

Sets the rotation angle around the X-axis.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformSetRotateY (  SoTransform *    a_This,
s32    a_Angle
) 
 

Sets the rotation angle around the Y-axis.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformSetRotateZ (  SoTransform *    a_This,
s32    a_Angle
) 
 

Sets the rotation angle around the Z-axis.

Parameters:
a_This  This pointer
a_Angle  Angle. A Full circle is 256 degrees

void SoTransformSetScale (  SoTransform *    a_This,
sofixedpoint    a_ScaleX,
sofixedpoint    a_ScaleY,
sofixedpoint    a_ScaleZ
) 
 

Sets the uniform scale value.

Parameters:
a_This  This pointer
a_ScaleX  Fixed point scale factor. X component.
a_ScaleY  Fixed point scale factor. Y component.
a_ScaleZ  Fixed point scale factor. Z component.

void SoTransformSetTranslation (  SoTransform *    a_This,
sofixedpoint    a_X,
sofixedpoint    a_Y,
sofixedpoint    a_Z
) 
 

Sets the translational part of the transform.

Parameters:
a_This  This pointer
a_X  Fixed point X part of the translate
a_Y  Fixed point Y part of the translate
a_Z  Fixed point Z part of the translate

void SoTransformToInverseMatrix (  SoTransform *    a_This,
SoMatrix *    a_Matrix
) 
 

Returns a 3 by 4 matrix representation of the inverse of this transform.

Todo:
Optimize this method
Parameters:
a_This  This pointer
a_Matrix  [OUT] Resulting matrix

void SoTransformToMatrix (  SoTransform *    a_This,
SoMatrix *    a_Matrix
) 
 

Returns a 3 by 4 matrix representation of the transform.

Todo:
Optimize this method
Parameters:
a_This  This pointer
a_Matrix  [OUT] Resulting matrix

void SoTransformTranslate (  SoTransform *    a_This,
sofixedpoint    a_X,
sofixedpoint    a_Y,
sofixedpoint    a_Z
) 
 

Translates the transform.

The difference between this one and SoTransformSetTranslate is that in this Method the translation is added to the existing transformation.

Parameters:
a_This  This pointer
a_X  Fixed point X part of the translate
a_Y  Fixed point Y part of the translate
a_Z  Fixed point Z part of the translate

Copyright 2002 by the SGADE authors. See SoLicense.h or Visit the SGADE page for more information.