just a quick glance at the jgfx commands again, it looks like you need:
Poke Mat4=jGfx\Poke_Mat4.html=pMem, _11#, _12#, _13#, _14#, _21#, _22#, _23#, _24#, _31#, _32#, _33#, _34#, _41#, _42#, _43#, _44#
I will try this out on my current project see if it works. it should do. my current code uses :
for row = 0 to 3
for col = 0 to 3
valuef#=peek float(pDataPTR+idx)
limbsmatrix(frameMatrixCount,col,row).lid=limbstofix(lc).lid
limbsmatrix(frameMatrixCount,col,row).fMat=valuef#
limbsmatrix(frameMatrixCount,col,row).fMatNew=valuef#
inc i
if col = 1 and row = 3 //i=13 M42 (as per directx SDK matrix info)
poke float pDataPTR+idx,valuef#+newy
limbsmatrix(frameMatrixCount,col,row).fMatNew=valuef#+newy
limbsmatrix(frameMatrixCount,col,row).fMat=valuef#
endif
inc idx,4
next col
next row
So logical value 13 is actually physical value 14=pos y (OR row=3 and col=1 in my array), refer to directx SDK (transform matrix). So I'm basically grabbing _42# value and changing it.
Same will apply to rotations.

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