yaze/src/app/zelda3/dungeon/object_renderer.cc

#include "app/zelda3/dungeon/object_renderer.h"

namespace yaze {
namespace app {
namespace zelda3 {
namespace dungeon {

void DungeonObjectRenderer::LoadObject(uint16_t objectId,
                                       std::array<uint8_t, 16>& sheet_ids) {
  vram_.sheets = sheet_ids;

  rom_data_ = rom()->vector();
  // Prepare the CPU and memory environment
  memory_.Initialize(rom_data_);

  // Fetch the subtype pointers for the given object ID
  auto subtypeInfo = FetchSubtypeInfo(objectId);

  // Configure the object based on the fetched information
  ConfigureObject(subtypeInfo);

  // Run the CPU emulation for the object's draw routines
  RenderObject(subtypeInfo);
}

SubtypeInfo DungeonObjectRenderer::FetchSubtypeInfo(uint16_t object_id) {
  SubtypeInfo info;

  // Determine the subtype based on objectId
  uint8_t subtype = 1;

  // Based on the subtype, fetch the correct pointers
  switch (subtype) {
    case 1:  // Subtype 1
      info.subtype_ptr = core::subtype1_tiles + (object_id & 0xFF) * 2;
      info.routine_ptr = core::subtype1_tiles + 0x200 + (object_id & 0xFF) * 2;
      std::cout << "Subtype 1 " << std::hex << info.subtype_ptr << std::endl;
      std::cout << "Subtype 1 " << std::hex << info.routine_ptr << std::endl;
      break;
    case 2:  // Subtype 2
      info.subtype_ptr = core::subtype2_tiles + (object_id & 0x7F) * 2;
      info.routine_ptr = core::subtype2_tiles + 0x80 + (object_id & 0x7F) * 2;
      break;
    case 3:  // Subtype 3
      info.subtype_ptr = core::subtype3_tiles + (object_id & 0xFF) * 2;
      info.routine_ptr = core::subtype3_tiles + 0x100 + (object_id & 0xFF) * 2;
      break;
    default:
      // Handle unknown subtype
      throw std::runtime_error("Unknown subtype for object ID: " +
                               std::to_string(object_id));
  }

  return info;
}

void DungeonObjectRenderer::ConfigureObject(const SubtypeInfo& info) {
  cpu.A = 0x03D8;
  cpu.X = 0x03D8;
  cpu.DB = 0x7E;
  // VRAM target destinations
  cpu.WriteLong(0xBF, 0x7E2000);
  cpu.WriteLong(0xCB, 0x7E2080);
  cpu.WriteLong(0xC2, 0x7E2002);
  cpu.WriteLong(0xCE, 0x7E2082);
  cpu.SetAccumulatorSize(false);
  cpu.SetIndexSize(false);
}

/**
 * Example:
 * the STA $BF, $CD, $C2, $CE are the location of the object in the room
 * $B2 is used for size loop
 * so if object size is setted on 07 that draw code will be repeated 7 times
 * and since Y is increasing by 4 it makes the object draw from left to right

  RoomDraw_Rightwards2x2_1to15or32:
    #_018B89: JSR RoomDraw_GetSize_1to15or32
    .next
    #_018B8C: JSR RoomDraw_Rightwards2x2
    #_018B8F: DEC.b $B2
    #_018B91: BNE .next
    #_018B93: RTS

  RoomDraw_Rightwards2x2:
    #_019895: LDA.w RoomDrawObjectData+0,X
    #_019898: STA.b [$BF],Y
    #_01989A: LDA.w RoomDrawObjectData+2,X
    #_01989D: STA.b [$CB],Y
    #_01989F: LDA.w RoomDrawObjectData+4,X
    #_0198A2: STA.b [$C2],Y
    #_0198A4: LDA.w RoomDrawObjectData+6,X
    #_0198A7: STA.b [$CE],Y
    #_0198A9: INY #4
    #_0198AD: RTS
*/
void DungeonObjectRenderer::RenderObject(const SubtypeInfo& info) {
  cpu.PB = 0x01;
  cpu.PC = cpu.ReadWord(0x01 << 16 | info.routine_ptr);

  // Push an initial value to the stack we can read later to confirm we are
  // done
  cpu.PushLong(0x01 << 16 | info.routine_ptr);

  int i = 0;
  while (true) {
    uint8_t opcode = cpu.ReadByte(cpu.PB << 16 | cpu.PC);
    cpu.ExecuteInstruction(opcode);
    cpu.HandleInterrupts();

    if ((i != 0 &&
             (cpu.ReadWord((0x00 << 16 | cpu.SP() + 2)) == info.routine_ptr) ||
         0x8b93 == cpu.PC)) {
      std::cout << std::hex << cpu.ReadWord((0x00 << 16 | cpu.SP() + 3))
                << std::endl;
      break;
    }
    i++;
  }

  UpdateObjectBitmap();
}

// In the underworld, this holds a copy of the entire BG tilemap for
// Layer 1 (BG2) in TILEMAPA
// Layer 2 (BG1) in TILEMAPB
void DungeonObjectRenderer::UpdateObjectBitmap() {
  tilemap_.reserve(0x2000);
  for (int i = 0; i < 0x2000; ++i) {
    tilemap_.push_back(0);
  }
  int tilemap_offset = 0;

  // Iterate over tilemap in memory to read tile IDs
  for (int tile_index = 0; tile_index < 512; tile_index++) {
    // Read the tile ID from memory
    int tile_id = memory_.ReadWord(0x7E2000 + tile_index);
    std::cout << "Tile ID: " << std::hex << tile_id << std::endl;

    int sheet_number = tile_id / 32;
    std::cout << "Sheet number: " << std::hex << sheet_number << std::endl;

    int row = tile_id / 8;
    int column = tile_id % 8;

    int x = column * 8;
    int y = row * 8;

    auto sheet = rom()->mutable_graphics_sheet(vram_.sheets[sheet_number]);

    // Copy the tile from VRAM using the read tile_id
    sheet->Get8x8Tile(tile_id, x, y, tilemap_, tilemap_offset);
  }

  bitmap_.Create(256, 256, 8, tilemap_);
}

}  // namespace dungeon
}  // namespace zelda3
}  // namespace app
}  // namespace yaze