MTXInitStack

C Specification

#include<revolution/mtx.h>

void MTXInitStack ( MtxStack* sPtr, u32 numMtx );

Arguments

`sPtr`	Pointer to a `MtxStack` structure.
`numMtx`	Number of matrices in the matrix stack referenced by `sPtr`. This must be the same value as that used immediately before calling `MTXAllocStack`.

Return Values

None.

Description

This function is the companion to MTXAllocStack. After MTXAllocStack allocates memory to an MTXStack's stackBase pointer, MTXInitStack must be called to initialize the MTXStack's remaining members. MTXAllocStack and MTXInitStack are essentially two halves of the same function — MTXAllocStack was separated out and converted to a macro in mtx.h to expose its memory allocation call.

MTXInitStack sets sPtr->numMtx to numMtx and sets sPtr->stackPtr equal to NULL, indicating an empty stack.

Creation of a matrix stack must follow these steps:

a) Create a MtxStack structure either through a normal variable definition or by a call to a memory allocation routine. For example:

MtxStack sPtr ; MtxStackPtr sPtr = OSAlloc( sizeof(MtxStack) ) ;

b) Use the macro MTXAllocStack (sPtr,numMtx) to allocate numMtx matrices to sPtr->stackBase.

c) Initialize the remaining members of the MtxStack structure with a call to MTXInitStack. numMtx must have the same value as that used for MTXAllocStack.

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