i`m comfused please help

This is a discussion on i`m comfused please help within the Game Programming forums, part of the General Programming Boards category; hello there everybody i`m new to game programming and directx please can anyone tell what do this sentence mean ? ...

  1. #1
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    Exclamation i`m comfused please help

    hello there everybody
    i`m new to game programming and directx please can anyone tell what do this sentence mean ?

    int index = i * lockRect.Pitch / 4 + j;

    imageData[index] = 0xffff0000;

    what i cant understand why did i multiplyed lockedrect.pitch with i and then divide it by 4+j ?

  2. #2
    Supermassive black hole cboard_member's Avatar
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    We're going to need to see more than those two lines. Post us the full program / function.
    EDIT: Oh and code tags plskkkthxbai
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

  3. #3
    For Narnia! Sentral's Avatar
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    Maybe, you should learn the English language before you move onto C++!

    What are you trying to accomplish with that code? It does nothing from what I can see.

  4. #4
    Super Moderator VirtualAce's Avatar
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    int index = i * lockRect.Pitch / 4 + j;

    imageData[index] = 0xffff0000;
    The divide by 4 is to convert bytes into DWORDs or UINTs.. Pitch is expressed in bytes. 1 UINT or DWORD is 4 bytes.
    You should group your operations with parentheses to make for easier reading of the code.

    Code:
    int index = i * (lockRect.Pitch >> 2) + j;
    
    imageData[index] = 0xffff0000;
    Shift right is same as dividing by 2^shift.
    Shift left is same as multiplying by 2^shift.

    I would say your code worked as planned because multiplication is first, then division, then addition, etc, etc. But it's always a good idea to group the operations for clarity and to ensure the operations are being done in the correct order.

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    thanks everybody for the replays
    bubba thanks for the explanation

  6. #6
    Supermassive black hole cboard_member's Avatar
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    Ah, so we didn't need it all. Rather, Bubba didn't. Good ol' Bubs
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

  7. #7
    Super Moderator VirtualAce's Avatar
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    I'm here for ya's all.

    So don't go posting stuff I don't know anything about and we'll get along just fine. The stuff I don't know is pretty much everything John Carmack knows....so no John Carmack threads.

  8. #8
    For Narnia! Sentral's Avatar
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    What are Mega-Textures(tm)?

  9. #9
    Super Moderator VirtualAce's Avatar
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    Those crazy things he talked about for terrain and such which I still don't quite understand how they work or would work. I read the article but it was quite sparse and didn't make sense.
    I think it means generating a huge texture and then using it on a surface. The texture is so big that you would not get any repeating or tiling.

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