Function ParsePointer

src/lua/LuaGLPointers.cpp:181–242

//============================================================================//

static const void* ParsePointer(lua_State* L, int index, GLsizei count,
                                GLenum* dataType, int& maxElem, bool& useVBO,
                                GLenum arrayType) {
  const char* data = NULL;
  size_t size;
  size_t offset = 0;
  GLuint bufID = 0;

  if (dataType != NULL) {
    *dataType = (GLenum)luaL_checkint(L, index);
    index++;
  }

  if (lua_israwstring(L, index)) {
    data = lua_tolstring(L, index, &size);
    offset = luaL_optint(L, index + 1, 0) ;
  }
  else {
    const LuaGLBuffer* buf = LuaGLBufferMgr::TestLuaGLBuffer(L, index);
    if (buf == NULL) {
      luaL_error(L, "invalid data source");
    }
    offset = luaL_optint(L, index + 1, 0);

    size = buf->size;
    bufID = buf->id;

    if (bufID == 0) {
      maxElem = 0;
      return NULL;
    }
  }

  if (offset > size) {
    luaL_error(L, "offset exceeds data size");
  }
  data += offset;
  size -= offset;

  const int typeSize = LuaGLBufferMgr::GetTypeSize(*dataType);
  if (typeSize <= 0) {
    maxElem = 0;
  }
  maxElem = size / (count * typeSize);
  if (maxElem <= 0) {
    return NULL;
  }

  if (bufID == 0) {
    useVBO = false;
  }
  else {
    useVBO = true;
    glBindBuffer(GL_ARRAY_BUFFER, bufID);
  }

  CreateLuaRef(L, index, arrayType);
  maxElements[arrayType] = maxElem;