RE: [GD-Consoles] Textures vs. Polygons
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From: Awen L. <ali...@ed...> - 2001-11-21 08:57:28
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>2. Jamie/Awen: Sorry, I am not clear on what you mean by splitting the geometry matrices, could you explain this in more detail? Hope i'm going to describe what Jamie had in mind... Ok: objects verts/polys/etc are sorted and stripped using some criterions (polys batched on a per-material basis is a common practice). Strip best size, and neihgbouring choice, is generally choosen using many params considerations (GPU cache size ?). More specifically on a PS2, if you choose to use VU to do your mesh mathematics, the VU mem size may be one of these params. For an object, you need to compute the storage required by the VU to process one of your vertex (3d coords+normal+uvs+rgbs... etc.), and usually a matrix or two, to rotate and light your stuff. You have to be smart with you VU and make some decisions on what could stay for a while, and what must be quickly discarded to minimize DMA traffic. Matrices may be considered more 'static' than verts flow. For an animated object your need to add some skinning consideration to that point, and configure your mesh to require the least possible matrices swapping. And it shows naturally the way you choose to strip/sort your mesh polys. Ant it's a bit related to your texture details problem, since if you NEED to split your mesh into chunks because of matrices, why not having many materials per object, if you're a king of parallelization and swapping texture buffer, text upload cost stuff may be masked. Sorry to stay a bit vague, it begins to touch some dungeon secrets, around here ;) |