Posts by Arisotura - melonDS board

27th January 2024, 13:02 EST

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Kuribo64

4th October 2028, 17:38 EST

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Kuribo64

in the meantime you can watch some excellent cartoons like this

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Kuribo64

Posted by Generic aka RSDuck
are you sure the save file is not padded?

this. melonDS needs exact savefile sizes (it relies on the file size to determine the memory type).

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Kuribo64

welcome aboard!

I recommend you make a thread to ask about that error, though; this thread isn't going to be the best place for this

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Kuribo64

okay so

    // culling
    // TODO: work out how it works on the real thing
    // the normalization part is a wild guess

    Vertex *v0, *v1, *v2, *v3;
    s64 normalX, normalY, normalZ;
    s64 dot;

    v0 = &TempVertexBuffer[0];
    v1 = &TempVertexBuffer[1];
    v2 = &TempVertexBuffer[2];
    v3 = &TempVertexBuffer[3];

    normalX = ((s64)(v0->Position[1]-v1->Position[1]) * (v2->Position[3]-v1->Position[3]))
        - ((s64)(v0->Position[3]-v1->Position[3]) * (v2->Position[1]-v1->Position[1]));
    normalY = ((s64)(v0->Position[3]-v1->Position[3]) * (v2->Position[0]-v1->Position[0]))
        - ((s64)(v0->Position[0]-v1->Position[0]) * (v2->Position[3]-v1->Position[3]));
    normalZ = ((s64)(v0->Position[0]-v1->Position[0]) * (v2->Position[1]-v1->Position[1]))
        - ((s64)(v0->Position[1]-v1->Position[1]) * (v2->Position[0]-v1->Position[0]));

    while ((((normalX>>31) ^ (normalX>>63)) != 0) ||
           (((normalY>>31) ^ (normalY>>63)) != 0) ||
           (((normalZ>>31) ^ (normalZ>>63)) != 0))
    {
        normalX >>= 4;
        normalY >>= 4;
        normalZ >>= 4;
    }

    dot = ((s64)v1->Position[0] * normalX) + ((s64)v1->Position[1] * normalY) + ((s64)v1->Position[3] * normalZ);

    bool facingview = (dot < 0);

    if (facingview)
    {
        if (!(CurPolygonAttr & (1<<7)))
        {
            LastStripPolygon = NULL;
            return;
        }
    }
    else if (dot > 0)
    {
        if (!(CurPolygonAttr & (1<<6)))
        {
            LastStripPolygon = NULL;
            return;
        }
    }

this is the culling code that melonDS employs atm. it's not too far away from what the DS seems to use. however:

* on the DS, polygons always pass culling if they have v0==v2 or v1==v2, even if cull mode is 0.

** this would imply that the DS uses v2 as a base vertex. melonDS is using v1.
** it only checks X, Y and W. Z can be whatever.

* cases of dot=0 pass both culling modes 1 and 2, but not 0 (unless they match the exception above).

* the DS employs some mechanism for reducing precision of the normal components as needed so it doesn't overflow. the mechanism is weird tho. but for example specific input can cause erroneous cases of dot=0.

*actually, testing tends to hint the DS is using v0 as a base.

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Kuribo64

alternately we could make a 'consumer-toy' GL renderer that sacrifices accuracy in the name of betterer speeds (doing more aggressive polygon batching, etc)

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Kuribo64

we talked about it on IRC, actually there is a bug with audio sync: if SDL audio couldn't be initialized for whatever reason, it will still try to sync to the audio callback even though that is not running. the sync call has a delay so that it doesn't freeze entirely incase, but obviously that makes it slow as hell.

the bug is already fixed in the upcoming Qt frontend.

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Kuribo64

you can try disabling the framerate limiter, audio sync, vsync, on each melonDS instance

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Kuribo64

then again consumer-toys have pretty crappy GL drivers

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Kuribo64


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