Hi David,
>From: "David Yazel" <[EMAIL PROTECTED]>
>To: "Kelvin Chung" <[EMAIL PROTECTED]>
>Subject: Question on Rasters
>Date: Tue, 12 Jun 2001 19:09:05 -0400
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>Kelvin:
>
>I was wondering if you could take a second and explain what a raster is and
>how it is implemented on your side in DirectX and OpenGL? What is it
>designed for? I got a hint when I read that it was not pickable and assumed
>that it is not really 3d and not sent to the card, but BLTTED onto the back
>buffer before swap, but that is just a guess. If it is a 3d object then
>does it use texture memory? do you map it to quads? I am seeing very good
>results from texture mapped quads for overlays, but want to make sure I am
>going in the right direction before proceeding further.
>
>
OGL: Raster is implement as glDrawPixels()
So the whole raster is pass down to the native code every frame.
D3D: Don't have API similar to glDrawPixels(), so
raster is implement as texture and map it to two triangles (no
Quad support in D3D)
Only when the raster change will the texture send down to the
native code again.
So if raster change every frame, OGL approach is faster, otherwise
D3D approach should be faster.
- Kelvin
---------------
Java 3D Team
Sun Microsystems Inc.
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