Talk:PowerVR

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The end of this page talks a lot about "AIBs" - can anybody make that more clear? What is an AIB? ThomasHarte 14:34, 28 October 2005 (UTC)

AIB stands for Add-in-Board. An AIB supplier is someone who takes a (typically graphics) chipset and builds a graphics card around it. It's pretty much a Value-added reseller for graphics cards. Cmdrjameson 18:10, 28 October 2005 (UTC)

Perhaps worth mentioning some drawbacks of the tile-based renderer? Ones from the top of my head: tile memory is preallocated on the video RAM of the card, reducing the amount available for texturing. This would also place a hard-limit on the total number of polygons able to be submitted per frame, after which no more polygons could be drawn. More awkwardly, this also puts a hard-limit on the maximum number of polygons allowed per-tile; which is far less predictable in practice. On the Dreamcase either of these conditions would just cause a run-time exception. As I understand it on the PC, such an exception was dealt with by transporting all the polygon data back over the PCI bus to the main PC; allocating more video RAM (potentially swapping out textures etc) and then re-submitting the polygon data. This would cause a major delay in rendering. TheMoog 14:29, 17 February 2006 (UTC)

If the scene buffer overflows, the scene gets rendered in multiple passes. All the scene data collected so far will be used to render the first pass, storing depth and color buffers for subsequent passes. However, there are techniques like metatiling that help prevent such a situation. 20:46, 20 April 2006 (UTC)

Does Intel 2900G carry the codename "Stanwood"? If so, it is based on MBX not SGX. 20:46, 20 April 2006 (UTC)

[edit] Infinite plane rendering

I remember reading in initial Dreamcast articles that "infinite plane rendering" was an important part of the VR technology. Can information be added about this?

Lazy8s: Infinite planes support was dropped after PowerVR Series 1, actually. They were a more flexible way of defining objects of which polygons were just a subset. Application designers, however, were overwhelming more familiar with conventional systems, so the later generations were optimized to deal with just triangles and quadrilaterals in Series 2 and eventually just triangles with Series 3.