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MGF PACKAGE DESCRIPTION |
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SCCSid "$SunId$ LBL" |
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RCSid "$Id$" |
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This package includes a description and parser for a new scene |
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description standard, called for the lack of a better name, MGF |
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Initializing the parser is the most important part of writing an MGF |
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program, and it is done through the mg_ehand array and a call to mg_init. |
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The global mg_ehand variable is an array of pointers to entity handler |
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functions. The arguments to these functions is always the same, an |
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functions. The arguments to these functions are always the same, an |
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argument count and an array of argument pointers (ala main). The return |
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value for these integer functions is one of the error codes defined in |
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parser.h, or MG_OK if the entity was handled correctly. You must |
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c_cmaterial variable will be pointing to a structure with all the |
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current settings. (Note that you would have to also set the color |
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mg_ehand entries to c_hcolor if you intended to support color |
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materials.) |
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materials.) A list of related mg_ehand assignments is given below: |
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mg_ehand[MG_E_COLOR] = c_hcolor; |
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mg_ehand[MG_E_CCT] = c_hcolor; |
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mg_ehand[MG_E_CMIX] = c_hcolor; |
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mg_ehand[MG_E_CSPEC] = c_hcolor; |
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mg_ehand[MG_E_CXY] = c_hcolor; |
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mg_ehand[MG_E_ED] = c_hmaterial; |
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mg_ehand[MG_E_IR] = c_hmaterial; |
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mg_ehand[MG_E_MATERIAL] = c_hmaterial; |
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mg_ehand[MG_E_NORMAL] = c_hvertex; |
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mg_ehand[MG_E_POINT] = c_hvertex; |
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mg_ehand[MG_E_RD] = c_hmaterial; |
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mg_ehand[MG_E_RS] = c_hmaterial; |
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mg_ehand[MG_E_SIDES] = c_hmaterial; |
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mg_ehand[MG_E_TD] = c_hmaterial; |
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mg_ehand[MG_E_TS] = c_hmaterial; |
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mg_ehand[MG_E_VERTEX] = c_hvertex; |
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In addition to the three handler functions, context.c contains a |
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few support routines that make life simpler. For vertices, there |
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is the c_getvertex call, which returns a pointer to a named vertex |
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simply returns 1 or 0 based on whether the passed color structure |
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is close to grey or not. Finally, there is the c_clearall routine, |
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which clears and frees all context data structures, and is the |
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principle action of the parser's mg_clear function. |
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principal action of the parser's mg_clear function. |
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Transform Support |
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================= |
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of the above would help to merge them. The most sure-fire approach to |
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linking identical vertices is therefore to hash the point and normal |
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values directly and use the functions in lookup.c to associate them. |
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You will have to write your own hash function, and I recommend making |
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You will have to write your own hash function, and we recommend making |
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one that allows a little slop so that nearly identical points hash to |
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the same value. |
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The simplest is a translator from MGF to MGF called mgfilt.c, which |
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produces on the standard output only those entities from the standard |
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input that are supported according to the command line arguments. For |
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example, one could remove everything but the raw, flat polygonal |
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input that are supported according to the first command line argument. |
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For example, one could remove everything but the raw, flat polygonal |
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geometry with the following command: |
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mgfilt v p f xf < any.mgf > faces.mgf |
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mgfilt v,p,f,xf any.mgf > faces.mgf |
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Note that the xf entity must also be included, for its support is |
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required by all geometric entities. |
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worked out. The intent is to offer it free of charge to all those who |
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wish to use it (with no guarantees, of course). However, we may decide |
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that copyright protections are necessary to prevent unauthorized versions |
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of the parser that do not properly support the MGF standard from getting |
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spread around. Since this is a pre-release, we trust that you will not |
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share it with anyone without getting our permission first. |
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of the parser, which do not properly support the MGF standard, from |
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getting spread around. Since this is a pre-release, we trust that you |
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will not share it with anyone without getting our permission first. |
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Questions |
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========= |
