Direct3D11 공부 25일차(ModelAnimator - Blend)

01 Jul 2021

Reading time ~2 minutes

Animation Blend

게임 엔진을 만지다 보면 각각 모션을 이동할때 현재의 상태에 따라 애니메이션을 섞에서 보여주는 기능이 있다.

블렌딩을 할 애니메이션을 현재 상테에 때라 보간해서 바꿔주면 된다.

ModelAnimator.h

private:
	struct BlendDesc
	{
		UINT Mode = 0;
		float Alpha = 0;
		Vector2 Padding;

		KeyframeDesc Clip[3];
	} blendDesc;

	ConstantBuffer* blendBuffer;
	ID3DX11EffectConstantBuffer* sBlendBuffer;

GPU에 넘길 BlendDesc를 만들고

ModelAnimator.cpp

void ModelAnimator::UpdateBlendMode()
{
	BlendDesc& desc = blendDesc;

	for (UINT i = 0; i < 3; i++)
	{
		ModelClip* clip = model->ClipByIndex(desc.Clip[i].Clip);

		desc.Clip[i].RunningTime += Time::Delta();

		float time = 1.0f / clip->FrameRate() / desc.Clip[i].Speed;
		if (desc.Clip[i].Time >= 1.0f)
		{
			desc.Clip[i].RunningTime = 0;

			desc.Clip[i].CurrFrame = (desc.Clip[i].CurrFrame + 1) % clip->FrameCount();
			desc.Clip[i].NextFrame = (desc.Clip[i].CurrFrame + 1) % clip->FrameCount();
		}
		desc.Clip[i].Time = desc.Clip[i].RunningTime / time;
	}
}

계속해서 업데이트를 한다. 여기까진 간단한데…

Shader

void SetBlendWorld(inout matrix world, VertexModel input)
{
    float indices[4] = { input.BlendIndices.x, input.BlendIndices.y, input.BlendIndices.z, input.BlendIndices.w };
    float weights[4] = { input.BlendWeights.x, input.BlendWeights.y, input.BlendWeights.z, input.BlendWeights.w };
    
    float4 c0, c1, c2, c3;
    float4 n0, n1, n2, n3;
    
    matrix curr = 0, next = 0;
    matrix currAnim[3];
    matrix anim = 0;
    
    matrix transform = 0;
    
    [unroll(4)]
    for (int i = 0; i < 4; i++)
    {
        [unroll(4)]
        for (int k = 0; k < 3; k++)
        {
            c0 = TransformsMap.Load(int4(indices[i] * 4 + 0, BlendFrames.Clip[k].CurrFrame, BlendFrames.Clip[k].Clip, 0));
            c1 = TransformsMap.Load(int4(indices[i] * 4 + 1, BlendFrames.Clip[k].CurrFrame, BlendFrames.Clip[k].Clip, 0));
            c2 = TransformsMap.Load(int4(indices[i] * 4 + 2, BlendFrames.Clip[k].CurrFrame, BlendFrames.Clip[k].Clip, 0));
            c3 = TransformsMap.Load(int4(indices[i] * 4 + 3, BlendFrames.Clip[k].CurrFrame, BlendFrames.Clip[k].Clip, 0));
            curr = matrix(c0, c1, c2, c3);
        
            n0 = TransformsMap.Load(int4(indices[i] * 4 + 0, BlendFrames.Clip[k].NextFrame, BlendFrames.Clip[k].Clip, 0));
            n1 = TransformsMap.Load(int4(indices[i] * 4 + 1, BlendFrames.Clip[k].NextFrame, BlendFrames.Clip[k].Clip, 0));
            n2 = TransformsMap.Load(int4(indices[i] * 4 + 2, BlendFrames.Clip[k].NextFrame, BlendFrames.Clip[k].Clip, 0));
            n3 = TransformsMap.Load(int4(indices[i] * 4 + 3, BlendFrames.Clip[k].NextFrame, BlendFrames.Clip[k].Clip, 0));
            next = matrix(n0, n1, n2, n3);
        
            currAnim[k] = lerp(curr, next, BlendFrames.Clip[k].Time);
        }
        int clipA = (int) BlendFrames.Alpha;
        int clipB = clipA + 1;
        
        float alpha = BlendFrames.Alpha;
        if(alpha > 1.0f)
        {
            alpha = BlendFrames.Alpha - 1.0f;
            
            if(BlendFrames.Alpha >= 2.0f)
            {
                clipA = 1;
                clipB = 2;
            }
        }
        
        anim = lerp(currAnim[clipA], currAnim[clipB], alpha);
        
        transform += mul(weights[i], anim);
    }
    
    world = mul(transform, world);
}

지금은 0,1,2만 해야 하기 때문에 애니메이션들을 보간 해주는데 각각 값에 따라 보간 해준다.

값에 따라 애니메이션이 섞여서 나온다.

DirectX