dusk/archive/assetchunk.c

/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "asset/asset.h"
#include "assert/assert.h"
#include "rpg/entity/entity.h"

#pragma pack(push, 1)
typedef struct {
  uint32_t tileCount;
  uint8_t modelCount;
  uint8_t entityCount;
} assetchunkheader_t;
#pragma pack(pop)

#pragma pack(push, 1)
typedef struct {
  tile_t tile;
} assetchunktiledata_t;
#pragma pack(pop)

#pragma pack(push, 1)
typedef struct {
  uint32_t vertexCount;
} assetchunkmodelheader_t;
#pragma pack(pop)

#pragma pack(push, 1)
typedef struct {
  entitytype_t entityType;
  uint8_t localX;
  uint8_t localY;
  uint8_t localZ;
} assetchunkentityheader_t;
#pragma pack(pop)

errorret_t assetChunkLoad(assetcustom_t custom) {
  assertNotNull(custom.output, "Output pointer cannot be NULL");
  assertNotNull(custom.zipFile, "Zip file pointer cannot be NULL");

  chunk_t *chunk = (chunk_t *)custom.output;
  assertTrue(chunk->meshCount == 0, "Chunk is not in a good state");

  // Read header
  assetchunkheader_t header;
  size_t bytesRead = zip_fread(
    custom.zipFile, &header, sizeof(assetchunkheader_t)
  );
  if(bytesRead != sizeof(assetchunkheader_t)) {
    zip_fclose(custom.zipFile);
    errorThrow("Failed to read chunk asset header.");
  }

  if(header.tileCount != CHUNK_TILE_COUNT) {
    zip_fclose(custom.zipFile);
    errorThrow(
      "Chunk asset has invalid tile count: %d (expected %d).",
      header.tileCount,
      CHUNK_TILE_COUNT
    );
  }

  if(header.modelCount > CHUNK_MESH_COUNT_MAX) {
    zip_fclose(custom.zipFile);
    errorThrow(
      "Chunk asset has too many models: %d (max %d).",
      header.modelCount,
      CHUNK_MESH_COUNT_MAX
    );
  }

  if(header.entityCount > CHUNK_ENTITY_COUNT_MAX) {
    zip_fclose(custom.zipFile);
    errorThrow(
      "Chunk asset has too many entities: %d (max %d).",
      header.entityCount,
      CHUNK_ENTITY_COUNT_MAX
    );
  }

  chunk->meshCount = header.modelCount;

  // Read tile data
  bytesRead = zip_fread(
    custom.zipFile,
    chunk->tiles,
    sizeof(assetchunktiledata_t) * header.tileCount
  );
  if(bytesRead != sizeof(assetchunktiledata_t) * header.tileCount) {
    zip_fclose(custom.zipFile);
    errorThrow("Failed to read chunk tile data.");
  }

  // For each model...
  uint32_t vertexIndex = 0;
  for(uint8_t i = 0; i < header.modelCount; i++) {
    assetchunkmodelheader_t modelHeader;
    bytesRead = zip_fread(
      custom.zipFile, &modelHeader, sizeof(assetchunkmodelheader_t)
    );
    if(bytesRead != sizeof(assetchunkmodelheader_t)) {
      zip_fclose(custom.zipFile);
      errorThrow("Failed to read chunk model header.");
    }

    if(
      vertexIndex + modelHeader.vertexCount >
      CHUNK_VERTEX_COUNT_MAX
    ) {
      zip_fclose(custom.zipFile);
      errorThrow("Chunk model vertex count exceeds maximum.");
    }
    
    // Read vertex data.
    bytesRead = zip_fread(
      custom.zipFile,
      &chunk->vertices[vertexIndex],
      sizeof(meshvertex_t) * modelHeader.vertexCount
    );
    if(bytesRead != sizeof(meshvertex_t) * modelHeader.vertexCount) {
      zip_fclose(custom.zipFile);
      errorThrow("Failed to read chunk model vertex data.");
    }

    // Init the mesh
    if(modelHeader.vertexCount > 0) {
      mesh_t *mesh = &chunk->meshes[i];
      meshInit(
        mesh,
        MESH_PRIMITIVE_TRIANGLES,
        modelHeader.vertexCount,
        &chunk->vertices[vertexIndex]
      );

      vertexIndex += modelHeader.vertexCount;
    } else {
      chunk->meshes[i].vertexCount = 0;
    }
  }

  // Read entity data
  for(uint8_t i = 0; i < header.entityCount; i++) {
    assetchunkentityheader_t entityHeader;
    bytesRead = zip_fread(
      custom.zipFile, &entityHeader, sizeof(assetchunkentityheader_t)
    );
    if(bytesRead != sizeof(assetchunkentityheader_t)) {
      zip_fclose(custom.zipFile);
      errorThrow("Failed to read chunk entity header.");
    }

    uint8_t entityIndex = entityGetAvailable();
    if(entityIndex == 0xFF) {
      zip_fclose(custom.zipFile);
      errorThrow("No available entity slots.");
    }

    entity_t *entity = &ENTITIES[entityIndex];
    entityInit(entity, (entitytype_t)entityHeader.entityType);
    entity->position.x = (
      (chunk->position.x * CHUNK_WIDTH) + entityHeader.localX
    );
    entity->position.y = (
      (chunk->position.y * CHUNK_HEIGHT) + entityHeader.localY
    );
    entity->position.z = (
      (chunk->position.z * CHUNK_DEPTH) + entityHeader.localZ
    );

    chunk->entities[i] = entityIndex;
  }

  errorOk();
}