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[Mathias 'cylab' Henze]

In the ShapeAtomPeers around line 630 there is a buffer splicing I don't get.

LWJGLs ShapeAtomPeer (624):

Code:

    IntBuffer subBuffer = ( (IntBuffer)igsa.getIndexData().getBuffer().position( i0 ) ).slice();
    subBuffer.limit( stripVertexCounts[ s ] ); // added to fix the strange triangles in the terrain test
    GL11.glDrawElements( mode, subBuffer );

I added the new limit there to fix the triangle test, but before that, the slice was completely unaltered.

If a slice at all, shouldn't this be

Code:

    IntBuffer subBuffer = ( (IntBuffer)igsa.getIndexData().getBuffer()).slice();
    subBuffer.position( i0 )
    subBuffer.limit( stripVertexCounts[ s ] );
    GL11.glDrawElements( mode, subBuffer );

to make sense?

But afaik a slice call creates a new (shared) Buffer erverytime, so wouldn't be

Code:

    IntBuffer buffer = (IntBuffer) igsa.getIndexData().getBuffer();
    int position = buffer.position();
    int limit = buffer.limit();
    buffer.position( i0 );
    buffer.limit( stripVertexCounts[s] );
    GL11.glDrawElements( mode, buffer );
    buffer.limit( limit );
    buffer.position( position );

a more effective implementation? It seems to be working, but maybe I am missing something, so I did not commit this yet.

Any Feedback? (Marvin? )

[Marvin Fröhlich]

Actually I was never happy with the way, index-buffers are used. I am very aware of the ugly, GC-expensive slice method. But I never found a way to avoid it. Certainly this is because I didn't understand the nio Buffers completely. I was just too lazy to read the documentation . I messed around a lot with ByteBuffers during the last days and finally understood them .

Please go ahead and fix that. It looks good. Without having the code with me I can try to blue-print my current thought of how I would implement that today.

Code:

IntBuffer buffer = (IntBuffer)igsa.getIndexData().getBuffer();
buffer.position( i0 );
buffer.limit( i0 + stripVertexCounts[ s ] );
GL11.glDrawElements( mode, buffer );

But if my code is nonsense, just forget it and fix it the way, you explained above.

Marvin

[Marvin Fröhlich]

Hey

I saw your changes and they still create a new IntBuffer because of the slice() method. I checked, if my code above would work and I am confident, that it will. And it doesn't create any garbage and should be preferred. Don't you agree? Could you maybe check it?

Marvin

[Mathias 'cylab' Henze]

The version you saw was just the limit() change to fix the terrain test with the LWJGL renderer. I just checked in the full version.

[Marvin Fröhlich]

The version you saw was just the limit() change to fix the terrain test with the LWJGL renderer. I just checked in the full version.

Ah, ok. I saw it now. It is perfect. Thanks a lot.

Marvin