wehub-resource-sync
96 lines
2.7 KiB
HLSL
96 lines
2.7 KiB
HLSL
// this code implements this shader in hlsl, https://www.shadertoy.com/view/XlBcRV
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sampler texSampler : register(s0);
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Texture2D<float4> inputTextureA : register(t0);
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Texture2D<float4> inputTextureB : register(t1);
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cbuffer ParamConstants : register(b0)
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{
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float Lod;
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float Amount;
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float2 ClampRange;
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float OutputMode;
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}
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cbuffer TimeConstants : register(b1)
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{
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float globalTime;
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float time;
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float runTime;
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float beatTime;
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}
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cbuffer Resolution : register(b2)
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{
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float TargetWidth;
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float TargetHeight;
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}
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struct vsOutput
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{
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float4 position : SV_POSITION;
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float2 texCoord : TEXCOORD;
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};
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#define mod(x,y) (x-y*floor(x/y))
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float intensity(float2 loc, float time) {
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float i0 = dot(inputTextureA.SampleLevel(texSampler, loc, Lod).rgb, float3(1,1,1));
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float i1 = dot(inputTextureB.SampleLevel(texSampler, loc, Lod).rgb, float3(1,1,1));
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return lerp(i0, i1, time);
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}
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float4 psMain(vsOutput psInput) : SV_TARGET{
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// lucas-kanade optical flow
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// https://en.wikipedia.org/wiki/Lucas%E2%80%93Kanade_method
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float LodScale = pow(2., Lod);
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float2x2 AtA = float2x2(0.0, 0.0, 0.0, 0.0);
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float2 Atb = float2(0.0, 0.0);
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float width, height;
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inputTextureA.GetDimensions(width, height);
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float2 iResolution = float2(width, height).xy;
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float2 p = (psInput.position.xy - float2(3., 3.)) / iResolution.xy;
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float xstart = p.x;
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float2 px_step = LodScale / iResolution.xy;
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for (int i = 0; i < 7; ++i) {
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p.x = xstart;
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for (int j = 0; j < 7; ++j) {
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float I = intensity(p, 0.0);
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float It = I - intensity(p, 2.0);
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float Ix = intensity(p + float2(1.0, 0.0) * px_step, 0.0) - I;
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float Iy = intensity(p + float2(0.0, 1.0) * px_step, 0.0) - I;
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AtA += float2x2(Ix * Ix, Ix * Iy, Ix * Iy, Iy * Iy);
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Atb -= float2(It * Ix, It * Iy);
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p.x += px_step.x;
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}
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p.y += px_step.y;
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}
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float2x2 AtAinv = float2x2(AtA[0][0], -AtA[0][1], -AtA[1][0], AtA[1][1]) /
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(AtA[0][0] * AtA[1][1] - AtA[1][0] * AtA[0][1]);
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float2 flow = mul(AtAinv, Atb);
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flow *= 0.1;
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if(isnan(flow.r)) flow.r=0;
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if(isnan(flow.g)) flow.g=0;
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float2 isSigned = sign(flow);
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flow *= isSigned; // only positive values
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flow = clamp(flow, ClampRange.x, ClampRange.y) - ClampRange.x; // clamp to positive range
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flow /= (ClampRange.y - ClampRange.x); // normalize
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flow *= isSigned; // back to signed
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float magnitude = length(flow.rg);
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flow *= Amount;
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flow = OutputMode < 0.5 ? flow : saturate(flow + 0.5);
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return float4(flow, magnitude, 1);
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}
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