Path: chuka.playstation.co.uk!news From: "Alex Herbert" Newsgroups: scee.yaroze.freetalk.english Subject: Re: Misc NY short questions Date: Thu, 13 Sep 2001 15:18:31 +0100 Organization: PlayStation Net Yaroze (SCEE) Lines: 55 Message-ID: <9nqf76$2qp3@www.netyaroze-europe.com> References: <01c13c3f$cf776880$LocalHost@pal-s-omnibook> NNTP-Posting-Host: host213-123-132-129.in-addr.btopenworld.com X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Hi pal, Do I qualify as a Guru? Well, I'll do my best... The GetTPage and semi-trans thing puzzled me a little too until I started playing with dynamic TMDs. Check out the file formats doc and the TSB parameter used in primitives, and all will become clear - or semi-transparent at least! TSB describes the TPage, texture bit-depth, and semi-trans rate, as returned by GetTPage. Perhaps GetTPage should have been called GetTSB? You can't poke the VRAM because it's not mapped to the CPU bus. The CPU and GPU have their own independent busses and memory and the only way to transfer data from one bus to the other is via DMA (Load/StoreImage). I understand your thinking that a 16-bit sprite should be faster than 4/8-bit ones, and you'd be right if it wasn't for the GPU's texture cache and CLUT cache. Each CLUT entry only needs to be read from VRAM once, so that's a maximum of 16 extra VRAM reads for a 4-bit texture. Also, a 4-bit texture requires just 1 VRAM read to put 4 pixels into the texture cache as opposed to 4 VRAM reads for a 16-bit texture. So, in theory at least, a 4-bit texture should be way faster than a 16-bit one. For example, the number of VRAM reads required for a 16x16 pixel, 16-bit sprite is: 16 x 16 (for texture) + 0 (for CLUT) = 256. Whereas the number of VRAM reads required for a 4-bit sprite of the same size is: 16 x 16 / 4 (for texture) + 16 (for CLUT) = 80. Hope this all makes sense, Alex "pal" wrote in message news:01c13c3f$cf776880$LocalHost@pal-s-omnibook... > Ok here are a few questions for NY gurus :) > > Why does GetTPage need the semi-transparency rate? > > How to poke in VRam (other than Load/StoreImage: I just want to poke a > byte/w/dw, hopefully quicker than by drawing a line/box/sprite)? > > Are 16bit sprites faster than 8/4bit ones? (I think they should because > they do not use a palette) > > > pal >