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Elite on the BBC Micro

Drawing ships: VERTEX

[BBC Micro disc version, Ship blueprints P]

Name: VERTEX [Show more] Type: Macro Category: Drawing ships Summary: Macro definition for adding vertices 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: VERTEX x, y, z, face1, face2, face3, face4, visibility See the deep dive on "Ship blueprints" for details of how vertices are stored in the ship blueprints, and the deep dive on "Drawing ships" for information on how vertices are used to draw 3D wireframe ships. Arguments: x The vertex's x-coordinate y The vertex's y-coordinate z The vertex's z-coordinate face1 The number of face 1 associated with this vertex face2 The number of face 2 associated with this vertex face3 The number of face 3 associated with this vertex face4 The number of face 4 associated with this vertex visibility The visibility distance, beyond which the vertex is not shown
MACRO VERTEX x, y, z, face1, face2, face3, face4, visibility IF x < 0 s_x = 1 << 7 ELSE s_x = 0 ENDIF IF y < 0 s_y = 1 << 6 ELSE s_y = 0 ENDIF IF z < 0 s_z = 1 << 5 ELSE s_z = 0 ENDIF s = s_x + s_y + s_z + visibility f1 = face1 + (face2 << 4) f2 = face3 + (face4 << 4) ax = ABS(x) ay = ABS(y) az = ABS(z) EQUB ax, ay, az, s, f1, f2 ENDMACRO