rotate part of texture around pivot - rotation

Question

I would like to "mask" a area of the sampled texture and rotate that part in circular motion. the mask is also moving around the uv map.
https://ibb.co/JshCDFZ
new to this.. I know I miss a step somewhere..
any tipps appreciated!
float4 PS_circleSampler(psInput In): SV_Target
{
float2 uv = In.TexCd.xy;
float4 col;
float s = sin(phase);
float c = cos(phase);
float2x2 rotationMatrix = float2x2(c, -s,
s, c);
float4 colOriginal = texA.Sample(linearSampler, uv);
float4 colRotated = texA.Sample(linearSampler, mul( pos - uv, rotationMatrix ));
float inCircle = 0.5 - distance (In.TexCd.xy, pos);
colOriginal *= 1- ceil(inCircle);
colRotated *= ceil(inCircle) ;
return colOriginal + colRotated;
}

Answer 1

found the solution myself..
rotating in vertex shader is easier because it uses a -1 to 1 coordinate system.
first translating the uv to the center, then roating, then translating back to its original pos
float2 pos;
float radius;
float phase;
Texture2D texA <string uiname="Texture A";>;
Texture2D texB <string uiname="Texture B";>;
cbuffer cbPerDraw : register( b0 )
{
float4x4 tVP : LAYERVIEWPROJECTION;
};
cbuffer cbPerObj : register( b1 )
{
float4x4 tW : WORLD;
};
SamplerState linearSampler
{
Filter = MIN_MAG_MIP_LINEAR;
AddressU = Clamp;
AddressV = Clamp;
};
struct vsInput
{
float4 PosO : POSITION;
float2 TexCd : TEXCOORD0;
};
struct psInput
{
float4 PosWVP: SV_Position;
float2 TexCd: TEXCOORD0;
float2 TexCdRotated: TEXCOORD1;
};
psInput VS(vsInput In)
{
psInput output;
float2 uv = In.TexCd;
float2 center = pos;
float s = sin(phase);
float c = cos(phase);
float2x2 rotationMatrix = float2x2(c, -s,
s, c);
float2 uv2 = uv - center; // translate into center
uv2 = mul(uv2, rotationMatrix); // rotate the space
uv2 += center; // move it back to the original place
output.TexCdRotated = uv2;
output.PosWVP = In.PosO;
output.TexCd = In.TexCd;
return output;
}
float4 PS_circleSampler(psInput In): SV_Target
{
float2 uv = In.TexCd.xy;
float2 uvRot = In.TexCdRotated.xy;
float4 colOriginal = texA.Sample(linearSampler, uv);
float4 colRotated = texA.Sample(linearSampler, uvRot );
float inCircle = radius - distance (In.TexCd.xy, pos);
colOriginal *= 1- ceil(inCircle);
colRotated *= ceil(inCircle) ;
return colOriginal + colRotated;
}
technique10 circleSampler
{
pass P0
{
SetVertexShader( CompileShader( vs_4_0, VS() ) );
SetPixelShader( CompileShader( ps_4_0, PS_circleSampler() ) );
}
}
``