Unpack a normal map. Use with BC5-encoded normal map to reconstruct Z and remap the values to [-1, 1] range

rd_vis_bc5nrm.hlsl

/* 
	A BC5 normal map texture visualization shader for RenderDoc.
  Usage: 
    1. Save this to %APPDATA%/qrenderdoc/ on Windows or ~/.local/share/qrenderdoc elsewhere
    2. Set Channels mode to Custom in RenderDoc Texture Viewer
    3. Select the shader from the dropdown menu
*/

SamplerState pointSampler : register(s0);
Texture2DArray<float4> texDisplayTex2DArray : register(t2);

float4 unpackNrmMap(float4 sampledMap)
{
	float2 xy = sampledMap.rg * 2.0f - float2(1.0f, 1.0f);
	float z = sqrt(saturate(1.0f - dot(xy, xy)));
	return float4(xy.xy, z, 1.0f);
}

float4 main(float4 pos : SV_Position, float4 uv : TEXCOORD0) : SV_Target0
{
	float4 col = texDisplayTex2DArray.Sample(pointSampler, float3(uv.xy, 0), 0);
	return (unpackNrmMap(col) + float4(1.0f, 1.0f, 1.0f, 0.0f)) * float4(0.5f, 0.5f, 0.5f, 1.0f); 
}

unpack_nrm_map.hlsl

float4 unpackNrmMap(float4 sampledMap)
{
	float2 xy = sampledMap.rg * 2.0f - float2(1.0f, 1.0f);
	float z = sqrt(saturate(1.0f - dot(xy, xy)));
	return float4(xy.xy, z, 1.0f);
}