Re: [Algorithms] VIPM With T&L - what about roam

[Sam K. <sa...@ip...>]

Jim,

I though of exactly the same thing a couple of hours after I posed my last
message!
This will certainly do the trick. thanks.

sam



-----Original Message-----
From: Jim Offerman <j.o...@in...>
To: gda...@li...
<gda...@li...>
Date: 12 September 2000 7:50 AM
Subject: Re: [Algorithms] VIPM With T&L - what about roam


>> ...
>> BUT, what about software transforms in situations where the split order
is
>> not known, i.e. VDPM or ROAM where polygons are denser towards the
camera?
>> you cant specify a range of verts for the software transform because it
>> quite literally could be any of them. HT&L is fine because of the only
>> transform indexed verts thing.
>>
>> Is there a solution to this?
>
>You could stream just the used vertices into a 'dynamic' vertexbuffer (i.e.
>one you are using with the DISCARDCONTENTS paradigm) before rendering each
>frame. Something like this:
>
>(pseudo code warnings apply)
>
>---- 8< ----
>void RenderDevice::Draw(Array<Vertex> &verts, Array<ushort> &indices) {
>
>    struct VertInfo {
>        bool isUsed;        // is this vertex used?
>        short newIndex;    // new index of this vertex (after streaming).
>    };
>
>    static VertInfo vertInfos[/* max. nr. of verts */];
>    static short newIndices[/* max. nr. of indices */];
>
>        // Clear all vertex info structures.
>    memset(vertInfos, 0, sizeof(VertInfo) * /* max. nr. of verts */);
>
>        // Rebuild the vertex list, using *only* used vertices.
>    for (short i = 0; i < indices.GetLength(), i++) {
>            // Get current vertex index.
>        index = indices[i];
>            // Check if we're using this vertex already...
>        if (vertInfos[index].isUsed == false) {
>                // If not, mark this vertex as used and remember it's
index.
>            vertInfos[index].newIndex = i;
>            vertInfos[index].isUsed    = true;
>            newIndices[i] = i;
>                // Write a vertex to our dynamic vertexbuffer
>            mDynVB->WriteVertex(i, verts[index]);
>        }
>            // Remap index.
>         newIndices[i] = verts[index].newIndex;
>    }
>        // Draw everything.
>    Draw(mDynVB, newIndices, indices.GetLength());
>}
>---- 8< ----
>
>It remains to be seen whether the above will actually speed up rendering,
>but it could.
>
>Jim Offerman
>Innovade
>
>
>The Atlantis Project
>http://www.theatlantisproject.com
>
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