Day 34 complete.

2026-04-15 11:58:51 -07:00
parent 713738b9f3
commit cd0ed29b30
5 changed files with 316 additions and 199 deletions
@@ -0,0 +1,144 @@
+#include "handmade_tile.h"
+
+static tile_chunk *GetTileChunk(tile_map *TileMap,
+                                U32 TileChunkX, U32 TileChunkY)
+{
+    tile_chunk *TileChunk = NULL;
+
+    if((TileChunkX >= 0) && (TileChunkX < TileMap->TileChunkCountX) &&
+       (TileChunkY >= 0) && (TileChunkY < TileMap->TileChunkCountY))
+    {
+        TileChunk = &TileMap->TileChunks[TileChunkY *
+                                       TileMap->TileChunkCountX +
+                                       TileChunkX];
+    }
+
+    return TileChunk;
+}
+
+static void CannonicalizeCoord(tile_map *TileMap, U32 *Tile, F32 *TileRel)
+{
+    /* NOTE: The world is assumed to be toroidal topology. If you step off
+             one end, you come back on the other. */
+    S32 Offset = RoundF32toS32(*TileRel / TileMap->TileSideInMeters);
+    *Tile += Offset;
+    *TileRel -= (F32)Offset * TileMap->TileSideInMeters;
+
+    ASSERT(*TileRel >= -0.5f*TileMap->TileSideInMeters);
+    ASSERT(*TileRel <= 0.5f*TileMap->TileSideInMeters);
+}
+
+static tile_map_position RecannonicalizePosition(tile_map *TileMap,
+                                                 tile_map_position Pos)
+{
+    tile_map_position Result = Pos;
+
+    CannonicalizeCoord(TileMap, &Result.AbsTileX, &Result.TileRelX);
+    CannonicalizeCoord(TileMap, &Result.AbsTileY, &Result.TileRelY);
+
+    return Result;
+}
+
+static tile_chunk_position GetChunkPositionFor(tile_map *TileMap,
+                                               U32 AbsTileX, U32 AbsTileY)
+{
+    tile_chunk_position Result;
+
+    Result.TileChunkX = AbsTileX >> TileMap->ChunkShift;
+    Result.TileChunkY = AbsTileY >> TileMap->ChunkShift;
+    Result.RelTileX   = AbsTileX & TileMap->ChunkMask;
+    Result.RelTileY   = AbsTileY & TileMap->ChunkMask;
+
+    return Result;
+}
+
+static U32 GetTileValueUnchecked(tile_map *TileMap, tile_chunk *TileChunk,
+                                  U32 TileX, U32 TileY)
+{
+    U32 TileChunkValue;
+
+    ASSERT(TileChunk);
+    ASSERT(TileX < TileMap->ChunkDim);
+    ASSERT(TileY < TileMap->ChunkDim);
+
+    TileChunkValue = TileChunk->Tiles[TileY * TileMap->ChunkDim + TileX];
+    return TileChunkValue;
+}
+
+static U32 GetTileChunkValue(tile_map *TileMap, tile_chunk *TileChunk,
+                             U32 TestTileX, U32 TestTileY)
+{
+    U32 TileChunkValue = 0;
+
+    if(TileChunk) {
+        TileChunkValue = GetTileValueUnchecked(TileMap,
+                                               TileChunk,
+                                               TestTileX, TestTileY);
+    }
+
+    return TileChunkValue;
+}
+
+static void SetTileValueUnchecked(tile_map *TileMap, tile_chunk *TileChunk,
+                                 U32 TileX, U32 TileY, U32 TileValue)
+{
+    ASSERT(TileChunk);
+    ASSERT(TileX < TileMap->ChunkDim);
+    ASSERT(TileY < TileMap->ChunkDim);
+
+    TileChunk->Tiles[TileY * TileMap->ChunkDim + TileX] = TileValue;
+}
+
+static void SetTileChunkValue(tile_map *TileMap, tile_chunk *TileChunk,
+                             U32 TestTileX, U32 TestTileY, U32 TileValue)
+{
+    SetTileValueUnchecked(TileMap,
+                          TileChunk,
+                          TestTileX, TestTileY,
+                          TileValue);
+}
+
+static U32 GetTileValue(tile_map *TileMap, U32 AbsTileX, U32 AbsTileY)
+{
+    tile_chunk_position ChunkPos = GetChunkPositionFor(TileMap,
+                                                       AbsTileX,
+                                                       AbsTileY);
+    tile_chunk *TileChunk = GetTileChunk(TileMap,
+                                         ChunkPos.TileChunkX,
+                                         ChunkPos.TileChunkY);
+    U32 TileChunkValue = GetTileChunkValue(TileMap, TileChunk,
+                                           ChunkPos.RelTileX,
+                                           ChunkPos.RelTileY);
+    return TileChunkValue;
+}
+
+static B32 IsTileMapPointEmpty(tile_map *TileMap, tile_map_position CanPos)
+{
+    B32 Empty;
+
+    U32 TileChunkValue = GetTileValue(TileMap,
+                                      CanPos.AbsTileX,
+                                      CanPos.AbsTileY);
+    Empty = (TileChunkValue == 0);
+    return Empty;
+}
+
+static void SetTileValue(memory_arena *Arena,
+                         tile_map *TileMap,
+                         U32 AbsTileX, U32 AbsTileY,
+                         U32 TileValue)
+{
+    tile_chunk_position ChunkPos;
+    tile_chunk *TileChunk;
+
+    ChunkPos = GetChunkPositionFor(TileMap, AbsTileX, AbsTileY);
+    TileChunk = GetTileChunk(TileMap,
+                             ChunkPos.TileChunkX,
+                             ChunkPos.TileChunkY);
+    ASSERT(TileChunk); /* TODO: On-deman tile chunk creation. */
+
+    SetTileChunkValue(TileMap, TileChunk,
+                     ChunkPos.RelTileX,
+                     ChunkPos.RelTileY,
+                     TileValue);
+}