C++ TCacheEntryBase::BytesPerRow方法代码示例

//.........这里部分代码省略.........
	//
	// In most cases, the fastest way is to use only one texture cache entry for the same address. Usually,
	// when a texture changes, the old version of the texture is unlikely to be used again. If there were
	// new cache entries created for normal texture updates, there would be a slowdown due to a huge amount
	// of unused cache entries. Also thanks to texture pooling, overwriting an existing cache entry is
	// faster than creating a new one from scratch.
	//
	// Some games use the same address for different textures though. If the same cache entry was used in
	// this case, it would be constantly overwritten, and effectively there wouldn't be any caching for
	// those textures. Examples for this are Metroid Prime and Castlevania 3. Metroid Prime has multiple
	// sets of fonts on each other stored in a single texture and uses the palette to make different
	// characters visible or invisible. In Castlevania 3 some textures are used for 2 different things or
	// at least in 2 different ways(size 1024x1024 vs 1024x256).
	//
	// To determine whether to use multiple cache entries or a single entry, use the following heuristic:
	// If the same texture address is used several times during the same frame, assume the address is used
	// for different purposes and allow creating an additional cache entry. If there's at least one entry
	// that hasn't been used for the same frame, then overwrite it, in order to keep the cache as small as
	// possible. If the current texture is found in the cache, use that entry.
	//
	// For efb copies, the entry created in CopyRenderTargetToTexture always has to be used, or else it was
	// done in vain.
	std::pair<TexCache::iterator, TexCache::iterator> iter_range = textures_by_address.equal_range((u64)address);
	TexCache::iterator iter = iter_range.first;
	TexCache::iterator oldest_entry = iter;
	int temp_frameCount = 0x7fffffff;
	TexCache::iterator unconverted_copy = textures_by_address.end();

	while (iter != iter_range.second)
	{
		TCacheEntryBase* entry = iter->second;
		// Do not load strided EFB copies, they are not meant to be used directly
		if (entry->IsEfbCopy() && entry->native_width == nativeW && entry->native_height == nativeH &&
			entry->memory_stride == entry->BytesPerRow())
		{
			// EFB copies have slightly different rules as EFB copy formats have different
			// meanings from texture formats.
			if ((base_hash == entry->hash && (!isPaletteTexture || g_Config.backend_info.bSupportsPaletteConversion)) ||
				IsPlayingBackFifologWithBrokenEFBCopies)
			{
				// TODO: We should check format/width/height/levels for EFB copies. Checking
				// format is complicated because EFB copy formats don't exactly match
				// texture formats. I'm not sure what effect checking width/height/levels
				// would have.
				if (!isPaletteTexture || !g_Config.backend_info.bSupportsPaletteConversion)
					return ReturnEntry(stage, entry);

				// Note that we found an unconverted EFB copy, then continue.  We'll
				// perform the conversion later.  Currently, we only convert EFB copies to
				// palette textures; we could do other conversions if it proved to be
				// beneficial.
				unconverted_copy = iter;
			}
			else
			{
				// Aggressively prune EFB copies: if it isn't useful here, it will probably
				// never be useful again.  It's theoretically possible for a game to do
				// something weird where the copy could become useful in the future, but in
				// practice it doesn't happen.
				iter = InvalidateTexture(iter);
				continue;
			}
		}
		else
		{
			// For normal textures, all texture parameters need to match