3DRW File Format © Copyright 1995, 1996 Jose M. Arnesto (Keved / Capsule) Copyright ********* The 3DRW file format is copyright 1995, 1996 by Jose M. Arnesto (Keved / Capsule). This format can only be used in Amiga programs and its use on other platforms is prohibited. Introduction ************ The idea behind 3DRW was to create a file format to store 3D objects. Many others were available, but all of them were too complicated to use in demos, with features never needed in them. 3DRW is much simpler than all of them, so its use in scene productions is easier. The author ********** Please, if you like TDDD to Raw or the 3DRW format and use any of them often, send me a postcard of your hometown. It is nice to hear about Amiga mates out there. You can contact me at this address: Jose M. Arnesto c/ Pando, 2-2șA 39300 Torrelavega Spain jarnesto@bitmailer.net Description *********** A 3DRW file begins with a header. The offset of the points list is relative to the beginning of the file, and a value of zero means that the object only has points, not faces. 0000 LONG '3DRW' 0004 WORD file version (currently set to zero) 0006 LONG offset of the points list At present, 3DRW files can only store an object. It is described as a list of faces, which is optional, and a list of points. 3DRW describes faces as triangles, composed by three points each. The list of faces, if present, begins with a word containing the number of faces minus one, as it is prepared to be used as counter in a dbf loop. Each face begins with a word for the color of that face, which will currently be set to zero. Six more words contain the numbers of the points that compose that face, as 3DRW describes them as triangles, and each vertex has an starting point and an end point. That numbers, if multiplicated by four, can be used as offsets in a 2D list of the points coordinates. The points in each face are clock-wise ordered, so they can be easily used in light source routines. 0010 WORD number of faces - 1 (for dbf) 0012 WORD color of this face (currently set to zero) 0014 WORD point number 00 0016 WORD point number 01 0018 WORD point number 10 0020 WORD point number 11 0022 WORD point number 20 0024 WORD point number 21 The list of points begins at the point described at the file header. It has a word containing the number of points minus one, to use it in a dbf file. Then, each point has an X, Y, and Z coordinate. 0000 WORD number of points - 1 (for dbf) 0002 WORD x coordinate 0004 WORD y coordinate 0006 WORD z coordinate Usage ***** To use an 3DRW file in your demo, first of all, load it or incbin it. Then, use the offset of the points list to obtaing the starting address of the list of points. Do any operations to the 3D coordinates of the points and store the result, projected to 2D, in another buffer (2Dbuf). In that buffer, each point will be composed of four bytes, that is, a word for its x coordinate and another one for its y coordinate. Then, use the list of faces to draw it, using the point numbers of each face as offsets to the 2D buffer (2Dbuf). A sample of assembly code is provided . Its only purpose is to serve as an example. lea buffer,a0 points to the file move.l a0,a1 copies pointer add.l 6(a0),a1 adds the offset to the points list add.l #10,a0 jumps over the header move.l a0,facelist stores pointer to the faces list move.l a1,pointlist stores pointer to the points list ... move.l pointlist,a0 points to the points list lea 2Dbuf,a1 points to the 2D coords buffer move.w (a0)+,d0 gets the number of points operate3D move.w (a0)+,d1 gets x coordinate move.w (a0)+,d2 gets y coordinate move.w (a0)+,d3 gets z coordinate ... operates in 3D and projects to 2D move.w d4,(a1)+ stores x coordinate move.w d4,(a1)+ stores y coordinate dbf d0,operate3D ... move.l faceslist,a0 points to the faces list lea 2Dbuf,a1 points to the 2D coords buffer move.w (a0)+,d0 gets number of faces drawing move.w (a0)+,d1 gets color move.w (a0)+,d2 number of first point, first vertex move.w (a0)+,d3 number of second point, first vertex asl.w #2,d2 multiplicates offsets by four asl.w #2,d3 move.w (a1,d2),d4 first point, first vertex, x coord move.w 2(a1,d2),d5 first point, first vertex, y coord move.w (a1,d3),d6 second point, first vertex, x coord move.w 2(a1,d3),d7 second point, first vertex, y coord ... draw line move.w (a0)+,d2 number of first point, second vertex move.w (a0)+,d3 number of second point, second vertex asl.w #2,d2 multiplicates offsets by four asl.w #2,d3 move.w (a1,d2),d4 first point, second vertex, x coord move.w 2(a1,d2),d5 first point, second vertex, y coord move.w (a1,d3),d6 second point, second vertex, x coord move.w 2(a1,d3),d7 second point, second vertex, y coord ... draw line move.w (a0)+,d2 number of first point, third vertex move.w (a0)+,d3 number of second point, third vertex asl.w #2,d2 multiplicates offsets by four asl.w #2,d3 move.w (a1,d2),d4 first point, third vertex, x coord move.w 2(a1,d2),d5 first point, third vertex, y coord move.w (a1,d3),d6 second point, third vertex, x coord move.w 2(a1,d3),d7 second point, third vertex, y coord ... draw line dbf d0,drawing file incbin 'object.raw' facelist ds.l 1 pointlist ds.l 1 2Dbuf ds.l ??? (its length depends on the number of points)