Geometry (Metroid Prime): Difference between revisions
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| ''' | | '''Display List Size''' | ||
| '''Important: this value is not always reliable''' | | '''Important: this value is not always reliable''' | ||
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The primitive data is a | The primitive data is a GX display list. Each primitive begins with a byte that contains the primitive type in the upper 5 bits, and the vertex format setting in the lower 3; see below for possible settings. After that is a 16-bit vertex count, followed by a series of 16-bit vertex attribute indices. | ||
Note that you'll need to check some settings on the material to read the primitive data properly; the material determines which vertex attributes are present. The material also determines whether the surface is using lightmaps; if it is, then the first UV coordinate will be read out of the short UV array instead of the float one. | Note that you'll need to check some settings on the material to read the primitive data properly; the material determines which vertex attributes are present. The material also determines whether the surface is using lightmaps; if it is, then the first UV coordinate will be read out of the short UV array instead of the float one. | ||
There is no primitive count value; you'll need to continue reading data until you hit the end of the | There is no primitive count value; you'll need to continue reading data until you hit the end of the display list. There are a couple values you can use for reference; either the surface's section size, or the surface's end offset. '''Do not use the display list size setting from the surface header, though'''; it's usually accurate, but on some models it will give you a size smaller than the table actually is, and you'll miss a bunch of data. See Metroid3/4a11192a.CMDL from Prime 1 (icicle Ridley) or Metroid1/05778239.CMDL from Echoes (Samus's gunship) for an example of this. | ||
There are 7 primitive types supported by GX, indicated in the upper 5 bits of the flag value. Note that the game only ever actually uses triangles, triangle strips, and triangle fans; however, all of these primitives are supported by GX and are therefore supported by the game, and so they could be used in custom model files. | There are 7 primitive types supported by GX, indicated in the upper 5 bits of the flag value. Note that the game only ever actually uses triangles, triangle strips, and triangle fans; however, all of these primitives are supported by GX and are therefore supported by the game, and so they could be used in custom model files. | ||