INCLUDE "1-source-files/main-sources/elite-build-options.asm" _RELEASED = (_VARIANT = 1) _SOURCE_DISC = (_VARIANT = 2) _BUG_FIX = (_VARIANT = 3) GUARD &6000 \ Guard against assembling over screen memoryELITE-A MISSILE SHIP BLUEPRINT FILE Elite-A is an extended version of BBC Micro Elite by Angus Duggan The original Elite was written by Ian Bell and David Braben and is copyright Acornsoft 1984, and the extra code in Elite-A is copyright Angus Duggan The code on this site is identical to Angus Duggan's source discs (it's just been reformatted, and the label names have been changed to be consistent with the sources for the original BBC Micro disc version on which it is based) The commentary is copyright Mark Moxon, and any misunderstandings or mistakes in the documentation are entirely my fault The terminology and notations used in this commentary are explained at https://www.bbcelite.com/terminology The deep dive articles referred to in this commentary can be found at https://www.bbcelite.com/deep_dives
This source file produces the following binary file: * MISSILE.bin This gets loaded as part of elite-loader.asm and gets moved to &7F00 during the loading process.CODE% = &7F00 \ The address where the code will be run LOAD% = &2468 \ The address where the code will be loaded ORG CODE%Configuration variablesMACRO 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 ENDMACROName: VERTEX [Show more] Type: Macro Category: Drawing ships Summary: Macro definition for adding vertices to ship blueprints Deep dive: Ship blueprintsContext: See this macro on its own page References: This macro is used as follows: * SHIP_MISSILE uses VERTEX
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 shownMACRO EDGE vertex1, vertex2, face1, face2, visibility f = face1 + (face2 << 4) EQUB visibility, f, vertex1 << 2, vertex2 << 2 ENDMACROName: EDGE [Show more] Type: Macro Category: Drawing ships Summary: Macro definition for adding edges to ship blueprints Deep dive: Ship blueprintsContext: See this macro on its own page References: This macro is used as follows: * SHIP_MISSILE uses EDGE
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 wireframe 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 shownMACRO FACE normal_x, normal_y, normal_z, visibility IF normal_x < 0 s_x = 1 << 7 ELSE s_x = 0 ENDIF IF normal_y < 0 s_y = 1 << 6 ELSE s_y = 0 ENDIF IF normal_z < 0 s_z = 1 << 5 ELSE s_z = 0 ENDIF s = s_x + s_y + s_z + visibility ax = ABS(normal_x) ay = ABS(normal_y) az = ABS(normal_z) EQUB s, ax, ay, az ENDMACROName: FACE [Show more] Type: Macro Category: Drawing ships Summary: Macro definition for adding faces to ship blueprints Deep dive: Ship blueprintsContext: See this macro on its own page References: This macro is used as follows: * SHIP_MISSILE uses FACE
The following macro is used to build the ship blueprints: FACE normal_x, normal_y, normal_z, visibility See the deep dive on "Ship blueprints" for details of how faces are stored in the ship blueprints, and the deep dive on "Drawing ships" for information on how faces are used to draw 3D wireframe ships.
Arguments: normal_x The face normal's x-coordinate normal_y The face normal's y-coordinate normal_z The face normal's z-coordinate visibility The visibility distance, beyond which the edge is always shown.SHIP_MISSILE EQUB 0 \ Max. canisters on demise = 0 EQUW 40 * 40 \ Targetable area = 40 * 40 EQUB LO(SHIP_MISSILE_EDGES - SHIP_MISSILE) \ Edges data offset (low) EQUB LO(SHIP_MISSILE_FACES - SHIP_MISSILE) \ Faces data offset (low) EQUB 81 \ Max. edge count = (81 - 1) / 4 = 20 EQUB 0 \ Gun vertex = 0 EQUB 10 \ Explosion count = 1, as (4 * n) + 6 = 10 EQUB 102 \ Number of vertices = 102 / 6 = 17 EQUB 24 \ Number of edges = 24 EQUW 0 \ Bounty = 0 EQUB 36 \ Number of faces = 36 / 4 = 9 EQUB 14 \ Visibility distance = 14 EQUB 2 \ Max. energy = 2 EQUB 44 \ Max. speed = 44 EQUB HI(SHIP_MISSILE_EDGES - SHIP_MISSILE) \ Edges data offset (high) EQUB HI(SHIP_MISSILE_FACES - SHIP_MISSILE) \ Faces data offset (high) EQUB 2 \ Normals are scaled by = 2^2 = 4 EQUB %00000000 \ Laser power = 0 \ Missiles = 0 .SHIP_MISSILE_VERTICES \ x, y, z, face1, face2, face3, face4, visibility VERTEX 0, 0, 68, 0, 1, 2, 3, 31 \ Vertex 0 VERTEX 8, -8, 36, 1, 2, 4, 5, 31 \ Vertex 1 VERTEX 8, 8, 36, 2, 3, 4, 7, 31 \ Vertex 2 VERTEX -8, 8, 36, 0, 3, 6, 7, 31 \ Vertex 3 VERTEX -8, -8, 36, 0, 1, 5, 6, 31 \ Vertex 4 VERTEX 8, 8, -44, 4, 7, 8, 8, 31 \ Vertex 5 VERTEX 8, -8, -44, 4, 5, 8, 8, 31 \ Vertex 6 VERTEX -8, -8, -44, 5, 6, 8, 8, 31 \ Vertex 7 VERTEX -8, 8, -44, 6, 7, 8, 8, 31 \ Vertex 8 VERTEX 12, 12, -44, 4, 7, 8, 8, 8 \ Vertex 9 VERTEX 12, -12, -44, 4, 5, 8, 8, 8 \ Vertex 10 VERTEX -12, -12, -44, 5, 6, 8, 8, 8 \ Vertex 11 VERTEX -12, 12, -44, 6, 7, 8, 8, 8 \ Vertex 12 VERTEX -8, 8, -12, 6, 7, 7, 7, 8 \ Vertex 13 VERTEX -8, -8, -12, 5, 6, 6, 6, 8 \ Vertex 14 VERTEX 8, 8, -12, 4, 7, 7, 7, 8 \ Vertex 15 VERTEX 8, -8, -12, 4, 5, 5, 5, 8 \ Vertex 16 .SHIP_MISSILE_EDGES \ vertex1, vertex2, face1, face2, visibility EDGE 0, 1, 1, 2, 31 \ Edge 0 EDGE 0, 2, 2, 3, 31 \ Edge 1 EDGE 0, 3, 0, 3, 31 \ Edge 2 EDGE 0, 4, 0, 1, 31 \ Edge 3 EDGE 1, 2, 4, 2, 31 \ Edge 4 EDGE 1, 4, 1, 5, 31 \ Edge 5 EDGE 3, 4, 0, 6, 31 \ Edge 6 EDGE 2, 3, 3, 7, 31 \ Edge 7 EDGE 2, 5, 4, 7, 31 \ Edge 8 EDGE 1, 6, 4, 5, 31 \ Edge 9 EDGE 4, 7, 5, 6, 31 \ Edge 10 EDGE 3, 8, 6, 7, 31 \ Edge 11 EDGE 7, 8, 6, 8, 31 \ Edge 12 EDGE 5, 8, 7, 8, 31 \ Edge 13 EDGE 5, 6, 4, 8, 31 \ Edge 14 EDGE 6, 7, 5, 8, 31 \ Edge 15 EDGE 6, 10, 5, 8, 8 \ Edge 16 EDGE 5, 9, 7, 8, 8 \ Edge 17 EDGE 8, 12, 7, 8, 8 \ Edge 18 EDGE 7, 11, 5, 8, 8 \ Edge 19 EDGE 9, 15, 4, 7, 8 \ Edge 20 EDGE 10, 16, 4, 5, 8 \ Edge 21 EDGE 12, 13, 6, 7, 8 \ Edge 22 EDGE 11, 14, 5, 6, 8 \ Edge 23 .SHIP_MISSILE_FACES \ normal_x, normal_y, normal_z, visibility FACE -64, 0, 16, 31 \ Face 0 FACE 0, -64, 16, 31 \ Face 1 FACE 64, 0, 16, 31 \ Face 2 FACE 0, 64, 16, 31 \ Face 3 FACE 32, 0, 0, 31 \ Face 4 FACE 0, -32, 0, 31 \ Face 5 FACE -32, 0, 0, 31 \ Face 6 \ --- Mod: Code removed for Elite-A: ------------------> \IF _STH_DISC OR _IB_DISC \ \ FACE 0, 160, 110, 31 \ Face 7 \ FACE 0, 64, 4, 0 \ Face 8 \ \ELIF _SRAM_DISC \ \ FACE 0, 32, 0, 31 \ Face 7 \ FACE 0, 0, -176, 31 \ Face 8 \ \ENDIF \ --- And replaced by: --------------------------------> FACE 0, 32, 0, 31 \ Face 7 FACE 0, 0, -176, 31 \ Face 8 \ --- End of replacement ------------------------------>Name: SHIP_MISSILE [Show more] Type: Variable Category: Drawing ships Summary: Ship blueprint for a missile Deep dive: Ship blueprintsContext: See this variable on its own page References: No direct references to this variable in this source file.VEC \ --- Mod: Code removed for Elite-A: ------------------> \IF _STH_DISC OR _IB_DISC \ \ EQUW &0004 \ VEC = &7FFE \ \ \ \ This gets set to the value of the original IRQ1 vector \ \ by the loading process \ \ \ \ This default value is random workspace noise left over \ \ from the BBC Micro assembly process; it gets \ \ overwritten \ \ELIF _SRAM_DISC \ \ SKIP 2 \ VEC = &7FFE \ \ \ \ This gets set to the value of the original IRQ1 vector \ \ by the loading process \ \ENDIF \ --- And replaced by: --------------------------------> SKIP 2 \ VEC = &7FFE \ \ This gets set to the value of the original IRQ1 vector \ by the loading process \ --- End of replacement ------------------------------>Name: VEC [Show more] Type: Variable Category: Drawing the screen Summary: The original value of the IRQ1 vectorContext: See this variable on its own page References: No direct references to this variable in this source filePRINT "MISSILE" PRINT "Assembled at ", ~CODE% PRINT "Ends at ", ~P% PRINT "Code size is ", ~(P% - CODE%) PRINT "Execute at ", ~LOAD% PRINT "Reload at ", ~LOAD% PRINT "S.MISSILE ",~CODE%," ",~P%," ",~LOAD%," ",~LOAD% SAVE "3-assembled-output/MISSILE.bin", CODE%, P%, LOAD%Save MISSILE.bin
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Macro EDGE (category: Drawing ships)
Macro definition for adding edges to ship blueprints
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Macro FACE (category: Drawing ships)
Macro definition for adding faces to ship blueprints
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Variable SHIP_MISSILE (category: Drawing ships)
Ship blueprint for a missile
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Label SHIP_MISSILE_EDGES in variable SHIP_MISSILE
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Label SHIP_MISSILE_FACES in variable SHIP_MISSILE
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Macro VERTEX (category: Drawing ships)
Macro definition for adding vertices to ship blueprints
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