Sign in to follow this  
Anand Baumunk

DX11 Bottleneck in MD5 animation

Recommended Posts

Well met,


I have implemented animation into my 3d engine [dx11]. I chose the md5 format, known from doom 3 I think, because it appeared 

to be the most simple format for bonebased animations (correct me, if im wrong on this).

Anyway, I manage to make it work, but appearently I created a bottleneck somewhere, because even a very simple anymation with 3 bones and like 50 polys makes everything slow as hell when played more than 10 times at once on the screen. 


I doublechecked the code for the animation itself, im not allocating memory every frame or something like that. So my best guess is that it has to do with the passing from CPU to GPU, which is done like this:

D3D11_MAPPED_SUBRESOURCE mappedResource;
d3d11DevCon->Map(matrixBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
cbPerObject* dataPtr;
dataPtr = (cbPerObject*)mappedResource.pData;
dataPtr->worldMatrix = World;
dataPtr->viewMatrix = camView;
dataPtr->projectionMatrix = camProjection;
d3d11DevCon->Unmap(matrixBuffer, 0);
d3d11DevCon->VSSetConstantBuffers(0, 1, &matrixBuffer);
for(int i=0;i<numSubsets;i++){
d3d11DevCon->IASetIndexBuffer(subsets[i].indexBuff, DXGI_FORMAT_R32_UINT, 0);
d3d11DevCon->IASetVertexBuffers( 0, 1, &subsets[i].vertBuff, &stride, &offset );
d3d11DevCon->PSSetShaderResources( 0, 1, &subsets[i].texture);
d3d11DevCon->DrawIndexed(subsets[i].indices.size(), 0, 0 );

I am only using Vertex and Pixelshader, both very basic.


EDIT: After further inverstigation, I figured that this part is the slow one, not the actual rendering. It's the update for the vertices using the bones.

EDIT2: Okey, I managed to narrow down the problem - using more-poly objects makes me lose more performace. Therefore, the problem lies not in something nasty called per object, but something called per vertex/joint .... Or MD5 is just a really slow format, but I can't see why this would be the case. Someone please enlighten me :(

struct Weight{
int jointID;
float bias;
D3DXVECTOR3 normal;
struct ModelSubset{
int numTriangles;
vector<Vertex> vertices;
vector<DWORD> indices;
vector<Weight> weights;
ID3D11ShaderResourceView* texture;
vector<D3DXVECTOR3> positions;
VertexPosNormalTex *verts;
unsigned long *indis;
ID3D11Buffer* vertBuff; 
ID3D11Buffer* indexBuff;
void animatedModel::updateWithAnimation(float deltaTime, int animationID){
currentAnimationID = animationID;
animations[animationID].currAnimTime += deltaTime; // Update the current animation time
if(animations[animationID].currAnimTime > animations[animationID].totalAnimTime){animations[animationID].currAnimTime = 0.0f;}
// Which frame are we on
float currentFrame = animations[animationID].currAnimTime * animations[animationID].frameRate; 
int frame0 = floorf( currentFrame );
int frame1 = frame0 + 1;
// Make sure we don't go over the number of frames 
if(frame0 == animations[animationID].numFrames-1){frame1 = 0;}
float interpolation = currentFrame - frame0; // Get the remainder (in time) between frame0 and frame1 to use as interpolation factor
vector<joint> interpolatedSkeleton; // Create a frame skeleton to store the interpolated skeletons in
// Compute the interpolated skeleton
for( int i = 0; i < animations[animationID].numJoints; i++){
joint tempJoint;
joint joint0 = animations[animationID].frameSkeleton[frame0][i]; // Get the i'th joint of frame0's skeleton
joint joint1 = animations[animationID].frameSkeleton[frame1][i]; // Get the i'th joint of frame1's skeleton
tempJoint.parentID = joint0.parentID; // Set the tempJoints parent id
// Turn the two quaternions into XMVECTORs for easy computations
D3DXQUATERNION joint0Orient = D3DXQUATERNION(joint0.orientation.x, joint0.orientation.y, joint0.orientation.z, joint0.orientation.w);
D3DXQUATERNION joint1Orient = D3DXQUATERNION(joint1.orientation.x, joint1.orientation.y, joint1.orientation.z, joint1.orientation.w);
// Interpolate positions
tempJoint.pos.x = joint0.pos.x + (interpolation * (joint1.pos.x - joint0.pos.x));
tempJoint.pos.y = joint0.pos.y + (interpolation * (joint1.pos.y - joint0.pos.y));
tempJoint.pos.z = joint0.pos.z + (interpolation * (joint1.pos.z - joint0.pos.z));
// Interpolate orientations using spherical interpolation (Slerp)
D3DXQuaternionSlerp(&tempO, &joint0Orient, &joint1Orient, interpolation);
tempJoint.orientation.x = tempO.x;
tempJoint.orientation.y = tempO.y;
tempJoint.orientation.z = tempO.z;
tempJoint.orientation.w = tempO.w;
interpolatedSkeleton.push_back(tempJoint); // Push the joint back into our interpolated skeleton
for ( int k = 0; k < numSubsets; k++){
for ( int i = 0; i < subsets[k].vertices.size(); ++i ){
Vertex tempVert = subsets[k].vertices[i];
tempVert.pos = D3DXVECTOR3(0, 0, 0); // Make sure the vertex's pos is cleared first
tempVert.normal = D3DXVECTOR3(0,0,0); // Clear vertices normal
// Sum up the joints and weights information to get vertex's position and normal
for ( int j = 0; j < tempVert.WeightCount; ++j ){
Weight tempWeight = subsets[k].weights[tempVert.StartWeight + j];
joint tempJoint = interpolatedSkeleton[tempWeight.jointID];
// Convert joint orientation and weight pos to vectors for easier computation
D3DXQUATERNION tempJointOrientation = D3DXQUATERNION(tempJoint.orientation.x, tempJoint.orientation.y, tempJoint.orientation.z, tempJoint.orientation.w);
D3DXQUATERNION tempWeightPos = D3DXQUATERNION(tempWeight.pos.x, tempWeight.pos.y, tempWeight.pos.z, 0.0f);
// We will need to use the conjugate of the joint orientation quaternion
D3DXQUATERNION tempJointOrientationConjugate;
D3DXQuaternionInverse(&tempJointOrientationConjugate, &tempJointOrientation);
// Calculate vertex position (in joint space, eg. rotate the point around (0,0,0)) for this weight using the joint orientation quaternion and its conjugate
// We can rotate a point using a quaternion with the equation "rotatedPoint = quaternion * point * quaternionConjugate"
D3DXVECTOR3 rotatedPoint;
D3DXQUATERNION temp1, temp2;
D3DXQuaternionMultiply(&temp1, &tempJointOrientation, &tempWeightPos);
D3DXQuaternionMultiply(&temp2, &temp1, &tempJointOrientationConjugate);
rotatedPoint.x = temp2.x;rotatedPoint.y = temp2.y;rotatedPoint.z = temp2.z;
// Now move the verices position from joint space (0,0,0) to the joints position in world space, taking the weights bias into account
tempVert.pos.x += ( tempJoint.pos.x + rotatedPoint.x ) * tempWeight.bias;
tempVert.pos.y += ( tempJoint.pos.y + rotatedPoint.y ) * tempWeight.bias;
tempVert.pos.z += ( tempJoint.pos.z + rotatedPoint.z ) * tempWeight.bias;
// Compute the normals for this frames skeleton using the weight normals from before
// We can comput the normals the same way we compute the vertices position, only we don't have to translate them (just rotate)
D3DXQUATERNION tempWeightNormal = D3DXQUATERNION(tempWeight.normal.x, tempWeight.normal.y, tempWeight.normal.z, 0.0f);
// Rotate the normal
D3DXVECTOR3 rotatedPoint2;
D3DXQUATERNION temp3, temp4;
D3DXQuaternionMultiply(&temp3, &tempJointOrientation, &tempWeightPos);
D3DXQuaternionMultiply(&temp4, &temp3, &tempJointOrientationConjugate);
rotatedPoint2.x = temp4.x; rotatedPoint2.y = temp4.y; rotatedPoint2.z = temp4.z;
// Add to vertices normal and ake weight bias into account
tempVert.normal.x -= rotatedPoint2.x * tempWeight.bias;
tempVert.normal.y -= rotatedPoint2.y * tempWeight.bias;
tempVert.normal.z -= rotatedPoint2.z * tempWeight.bias;
subsets[k].positions[i] = tempVert.pos; // Store the vertices position in the position vector instead of straight into the vertex vector
subsets[k].vertices[i].normal = tempVert.normal; // Store the vertices normal
D3DXVec3Normalize(&subsets[k].vertices[i].normal, &subsets[k].vertices[i].normal);
// Put the positions into the vertices for this subset
for(int i = 0; i < subsets[k].vertices.size(); i++){
subsets[k].vertices[i].pos = subsets[k].positions[i];
subsets[k].verts[i].pos = subsets[k].vertices[i].pos;
subsets[k].verts[i].normal = subsets[k].vertices[i].normal;
subsets[k].verts[i].texcoord = subsets[k].vertices[i].texCoord;
d3d11DevCon->Map(subsets[k].vertBuff, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedVertBuff);
VertexPosNormalTex *updatedV; updatedV = (VertexPosNormalTex *)mappedVertBuff.pData;
for(int h=0;h<subsets[k].vertices.size();h++){
updatedV[h].pos = subsets[k].verts[h].pos;
updatedV[h].normal = subsets[k].verts[h].normal;
updatedV[h].texcoord = subsets[k].verts[h].texcoord;
d3d11DevCon->Unmap(subsets[k].vertBuff, 0);
Edited by gnomgrol

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Partner Spotlight

  • Forum Statistics

    • Total Topics
    • Total Posts
  • Similar Content

    • By evelyn4you
      i have read very much about the binding of a constantbuffer to a shader but something is still unclear to me.
      e.g. when performing :   vertexshader.setConstantbuffer ( buffer,  slot )
       is the buffer bound
      a.  to the VertexShaderStage
      b. to the VertexShader that is currently set as the active VertexShader
      Is it possible to bind a constantBuffer to a VertexShader e.g. VS_A and keep this binding even after the active VertexShader has changed ?
      I mean i want to bind constantbuffer_A  to VS_A, an Constantbuffer_B to VS_B  and  only use updateSubresource without using setConstantBuffer command every time.

      Look at this example:
      SetVertexShader ( VS_A )
      vertexshader.setConstantbuffer ( buffer_A,  slot_A )
      perform drawcall       ( buffer_A is used )

      SetVertexShader ( VS_B )
      vertexshader.setConstantbuffer ( buffer_B,  slot_A )
      perform drawcall   ( buffer_B is used )
      SetVertexShader ( VS_A )
      perform drawcall   (now which buffer is used ??? )
      I ask this question because i have made a custom render engine an want to optimize to
      the minimum  updateSubresource, and setConstantbuffer  calls
    • By noodleBowl
      I got a quick question about buffers when it comes to DirectX 11. If I bind a buffer using a command like:
      IASetVertexBuffers IASetIndexBuffer VSSetConstantBuffers PSSetConstantBuffers  and then later on I update that bound buffer's data using commands like Map/Unmap or any of the other update commands.
      Do I need to rebind the buffer again in order for my update to take effect? If I dont rebind is that really bad as in I get a performance hit? My thought process behind this is that if the buffer is already bound why do I need to rebind it? I'm using that same buffer it is just different data
    • By Rockmover
      I am really stuck with something that should be very simple in DirectX 11. 
      1. I can draw lines using a PC (position, colored) vertices and a simple shader just fine.
      2. I can draw 3D triangles using PCN (position, colored, normal) vertices just fine (even transparency and SpecularBlinnPhong shaders).
      However, if I'm using my 3D shader, and I want to draw my PC lines in the same scene how can I do that?
      If I change my lines to PCN and pass them to the 3D shader with my triangles, then the lighting screws them all up.  I only want the lighting for the 3D triangles, but no SpecularBlinnPhong/Lighting for the lines (just PC). 
      I am sure this is because if I change the lines to PNC there is not really a correct "normal" for the lines.  
      I assume I somehow need to draw the 3D triangles using one shader, and then "switch" to another shader and draw the lines?  But I have no clue how to use two different shaders in the same scene.  And then are the lines just drawn on top of the triangles, or vice versa (maybe draw order dependent)?  
      I must be missing something really basic, so if anyone can just point me in the right direction (or link to an example showing the implementation of multiple shaders) that would be REALLY appreciated.
      I'm also more than happy to post my simple test code if that helps as well!
    • By Reitano
      I am writing a linear allocator of per-frame constants using the DirectX 11.1 API. My plan is to replace the traditional constant allocation strategy, where most of the work is done by the driver behind my back, with a manual one inspired by the DirectX 12 and Vulkan APIs.
      In brief, the allocator maintains a list of 64K pages, each page owns a constant buffer managed as a ring buffer. Each page has a history of the N previous frames. At the beginning of a new frame, the allocator retires the frames that have been processed by the GPU and frees up the corresponding space in each page. I use DirectX 11 queries for detecting when a frame is complete and the ID3D11DeviceContext1::VS/PSSetConstantBuffers1 methods for binding constant buffers with an offset.
      The new allocator appears to be working but I am not 100% confident it is actually correct. In particular:
      1) it relies on queries which I am not too familiar with. Are they 100% reliable ?
      2) it maps/unmaps the constant buffer of each page at the beginning of a new frame and then writes the mapped memory as the frame is built. In pseudo code:
 = device.Map(page.buffer)
          Alloc(size, initData)
              memcpy( + page.start, initData, size)
          Alloc(size, initData)
              memcpy( + page.start, initData, size)
      (Note: calling Unmap at the end of a frame prevents binding the mapped constant buffers and triggers an error in the debug layer)
      Is this valid ? 
      3) I don't fully understand how many frames I should keep in the history. My intuition says it should be equal to the maximum latency reported by IDXGIDevice1::GetMaximumFrameLatency, which is 3 on my machine. But, this value works fine in an unit test while on a more complex demo I need to manually set it to 5, otherwise the allocator starts overwriting previous frames that have not completed yet. Shouldn't the swap chain Present method block the CPU in this case ?
      4) Should I expect this approach to be more efficient than the one managed by the driver ? I don't have meaningful profile data yet.
      Is anybody familiar with the approach described above and can answer my questions and discuss the pros and cons of this technique based on his experience ? 
      For reference, I've uploaded the (WIP) allocator code at  Feel free to adapt it in your engine and please let me know if you spot any mistakes
      Stefano Lanza
    • By Matt Barr
      Hey all. I've been working with compute shaders lately, and was hoping to build out some libraries to reuse code. As a prerequisite for my current project, I needed to sort a big array of data in my compute shader, so I was going to implement quicksort as a library function. My implementation was going to use an inout array to apply the changes to the referenced array.

      I spent half the day yesterday debugging in visual studio before I realized that the solution, while it worked INSIDE the function, reverted to the original state after returning from the function.

      My hack fix was just to inline the code, but this is not a great solution for the future.  Any ideas? I've considered just returning an array of ints that represents the sorted indices.
  • Popular Now