Dynamictexture Data Update in UE4

Recently implemented a real-time mesh vertex animation in UE4, with a large number of vertices (hundreds of thousands of levels)

The first is to create the dynamic Vertex Buffer, then each frame to update the vertex data, found that the efficiency is lower

The bottleneck of efficiency is in the calculation of vertex coordinates, after all, there is a lot of

Then changed to be based on vertex Texture (material in the World Position Offset) Implementation, then VB will not update, only need to update each frame Texture

In this way, although the amount of data transmitted is consistent, it is possible to calculate a portion of the vertex coordinates into the GPU side, which greatly reduces the CPU pressure

The actual measurement found that the gamethread time consumption is still very high, the further optimization is to throw this part of the operation into the background thread [CPP] view plain copy void Adynamictexturetestcharacter::       Updateingamethread () {ftexture2dmipmap& Mip = dynamictexture->platformdata->mips[0];       fvector4* Dest = (fvector4*) Mip.BulkData.Lock (lock_read_write);       Writetexturedata (Dest);       Mip.BulkData.Unlock ();   Dynamictexture->updateresource (); }
After a test, crash, carefully see, the original is Ftexture2d::updateresource () will re-create the D3D texture object, the correlation function must be gamethread call in order to

The way that the data update itself is problematic, can not be directly updated to the corresponding D3D texture it. Search UE4 code, found that Ftwitchlivestreaming::updatewebcamtexture () has more efficient implementation, the general idea is to send the data to Renderthread to update directly, The call is Rhiupdatetexture2d[CPP] View plain Copy void adynamictexturetestcharacter::updateinrenderthread ()    {        fvector4* dest = databuffer.getdata ();        Writetexturedata (Dest);          struct FUpdateTextureContext        {           uint8*  sourcebuffer;    // render thread assumes ownership            uint32 BufferPitch;            FTexture2DResource* DestTextureResource;       }  updatetexturecontext =       {             (uint8*) dest,           sizeof (FVECTOR4)  * dynamictExture->getsizex (),            (ftexture2dresource*) dynamictexture->resource       };           enqueue_unique_render_command_oneparameter (            updatedynamictexture,           FUpdateTextureContext,  context, updatetexturecontext,           {           const fupdatetextureregion2d updateregion (            0, 0,       //  Dest X, Y           0, 0,        // Source X, Y            context.desttExtureresource->getsizex (), // width            Context.desttextureresource->getsizey ());    // height              rhiupdatetexture2d (                context.desttextureresource->gettexture2drhi (),   //  Destination GPU texture                0,                                                // mip map index                UpdateRegion,                                     // Update region                Context.BufferPitch,                          // Source buffer pitch                context.sourcebuffer);                           // source  buffer pointer       });  }  
This practice is no longer authorized to run Gamethread, so the performance impact is relatively small. The actual test of the call thread execution time is about 1ms faster than the previous one, which is still quite large for the FPS effect

Resources

Https://wiki.unrealengine.com/Dynamic_Textures

From: http://blog.csdn.net/xoyojank/article/details/49232841