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Editorial Team
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Asked: 2026-05-22T17:14:18+00:00

I am trying to understand how the 9 values in the android.graphics.Matrix class are

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I am trying to understand how the 9 values in the android.graphics.Matrix class are used to render something (specifically a Bitmap).

I saw the defines for the 9 indices into the value array, however the naming convention did not seem to make much sense to me.

I have my own orientation system that I am using for all my objects in my engine. For me an orientation consists of a position, a forward vector, and a left vector.

I am trying to figure out how to take these 3 pieces of data (which are already mapped to screen space) and create an android.graphics.Matrix that will render my object’s bitmap as I would expect.

Any help would be appreciated.

Thanks

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1 Answer

  1. Editorial Team

    I eventually figured out the documentation. For anyone who was confused about the wording like I was, here is another explanation:

    [0,0 0,1 0,2]

    [1,0 1,1 1,2]

    [2,0 2,1 2,2]

    =

    [MSCALE_X MSKEW_X MTRANS_X]

    [MSKEW_Y MSCALE_Y MTRANS_Y]

    [MPERSP_0 MPERSP_1 MPERSP_2]

    =

    [scale.x diagonal.x pos.x]

    [diagonal.y scale.y pos.y]

    [0.0f 0.0f 1.0f]

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