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Date: Wed, 21 Sep 2016 10:31:08 -0700 (PDT)
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Subject: Accessing a sub-array in C from Ada in SDL
From: Lucretia <laguest9000@googlemail.com>
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Xref: news.eternal-september.org comp.lang.ada:31832
Date: 2016-09-21T10:31:08-07:00
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Hi,

I'm gone back to try and get some updates on SDLAda textures (and also surfaces). 

When locking a texture you get a pointer to the array and a pitch value to the next line. Mapping a 2D or 3D texture data from C onto a 2D or 3D Ada array is quite easy for a full image, by setting the address. So, currently I have this for a full frame:

Actual_Pixels    : Texture_2D_Array (1 .. Height, 1 .. Width) with
   Address => To_Address (Pixels);


But what if you want to lock a partial area of this texture? Ideally, we'd want to be able to set a stride/pitch value in the array declaration, something like:

Actual_Pixels    : Texture_2D_Array (1 .. Height, 1 .. Width) with
   Address => To_Address (Pixels),
   Stride  => Pitch;

As far as I can see, this is currently not possible, but I can see this as being immensely useful when working with C libs.

Luke.