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⌂ ∞ Elite on the BBC Micro

Drawing ships: EDGE

[BBC Micro disc version, Ship blueprints C]

       Name: EDGE                                                    [Show more]
       Type: Macro
   Category: Drawing ships
    Summary: Macro definition for adding edges to ship blueprints
  Deep dive: Ship blueprints

    Context: See this macro in context in the source code
 References: No direct references to this macro in this source file




 The following macro is used to build the ship blueprints:

   EDGE vertex1, vertex2, face1, face2, visibility

 See the deep dive on "Ship blueprints" for details of how edges are stored
 in the ship blueprints, and the deep dive on "Drawing ships" for information
 on how edges are used to draw 3D wiremesh ships.

 Arguments:

   vertex1              The number of the vertex at the start of the edge

   vertex1              The number of the vertex at the end of the edge

   face1                The number of face 1 associated with this edge

   face2                The number of face 2 associated with this edge

   visibility           The visibility distance, beyond which the edge is not
                        shown



MACRO EDGE vertex1, vertex2, face1, face2, visibility

 f = face1 + (face2 << 4)
 EQUB visibility, f, vertex1 << 2, vertex2 << 2

ENDMACRO