mirror of https://github.com/nmlgc/ReC98.git
42 lines
1.5 KiB
C++
42 lines
1.5 KiB
C++
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/// Collision bitmap
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/// ----------------
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/// TH03 tracks collidable areas by maintaining a bitmap of each playfield,
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/// where each set bit corresponds to a tile occupied by a collidable entity.
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/// To save a bit of memory, these bitmaps are reduced to a quarter of the
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/// screen resolution: Every bit corresponds to a tile of 2×2 screen pixels,
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// or 2×1 VRAM pixels.
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typedef int collmap_tile_amount_t;
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// Constants
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// ---------
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static const pixel_t COLLMAP_TILE_W = 2;
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static const pixel_t COLLMAP_TILE_H = 2;
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static const char COLLMAP_TILE_W_BITS = 1;
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static const char COLLMAP_TILE_H_BITS = 1;
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static const size_t COLLMAP_MEMORY_W = ((PLAYFIELD_W / COLLMAP_TILE_W) / 8);
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static const size_t COLLMAP_H = (PLAYFIELD_H / COLLMAP_TILE_H);
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static const size_t COLLMAP_SIZE = (COLLMAP_MEMORY_W * COLLMAP_H);
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// ---------
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// Function parameters
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// -------------------
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// MODDERS: These two are stored at the same address in memory. Not having to
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// use a union here is one advantage of emitting these in an undecompilable ASM
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// translation unit, I guess...
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extern PlayfieldPoint collmap_center;
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extern PlayfieldPoint collmap_topleft;
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extern collmap_tile_amount_t collmap_stripe_tile_w;
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extern collmap_tile_amount_t collmap_tile_h;
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extern PlayfieldPoint collmap_bottomright;
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extern unsigned char collmap_pid;
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// Stored as columns from left to right, not rows from top to bottom.
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extern uint8_t collmap[PLAYER_COUNT][COLLMAP_MEMORY_W][COLLMAP_H];
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// -------------------
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/// ----------------
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