DownscaleBicubicYUV.pShader
2.6 KB
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//bicubic sharper (better for downscaling)
//note - this shader is adapted from the GPL bsnes shader, very good stuff there.
uniform Texture2D diffuseTexture;
uniform float4x4 yuvMat;
uniform float2 baseDimensionI;
SamplerState textureSampler
{
AddressU = Clamp;
AddressV = Clamp;
Filter = Linear;
};
struct VertData
{
float4 pos : SV_Position;
float2 texCoord : TexCoord0;
};
float weight(float x)
{
float ax = abs(x);
// Sharper version.
// May look better in some cases.
const float B = 0.0;
const float C = 0.75;
if (ax < 1.0)
return (pow(x, 2.0) * ((12.0 - 9.0 * B - 6.0 * C) * ax + (-18.0 + 12.0 * B + 6.0 * C)) + (6.0 - 2.0 * B)) / 6.0;
else if ((ax >= 1.0) && (ax < 2.0))
return (pow(x, 2.0) * ((-B - 6.0 * C) * ax + (6.0 * B + 30.0 * C)) + (-12.0 * B - 48.0 * C) * ax + (8.0 * B + 24.0 * C)) / 6.0;
else
return 0.0;
}
float4 weight4(float x)
{
return float4(
weight(x - 2.0),
weight(x - 1.0),
weight(x),
weight(x + 1.0));
}
float3 pixel(float xpos, float ypos)
{
return diffuseTexture.Sample(textureSampler, float2(xpos, ypos)).rgb;
}
float3 get_line(float ypos, float4 xpos, float4 linetaps)
{
return
pixel(xpos.r, ypos) * linetaps.r +
pixel(xpos.g, ypos) * linetaps.g +
pixel(xpos.b, ypos) * linetaps.b +
pixel(xpos.a, ypos) * linetaps.a;
}
float4 main(VertData input) : SV_Target
{
float2 stepxy = baseDimensionI;
float2 pos = input.texCoord + stepxy * 0.5;
float2 f = frac(pos / stepxy);
float4 linetaps = weight4(1.0 - f.x);
float4 columntaps = weight4(1.0 - f.y);
//make sure all taps added together is exactly 1.0, otherwise some (very small) distortion can occur
linetaps /= linetaps.r + linetaps.g + linetaps.b + linetaps.a;
columntaps /= columntaps.r + columntaps.g + columntaps.b + columntaps.a;
float2 xystart = (-1.5 - f) * stepxy + pos;
float4 xpos = float4(xystart.x, xystart.x + stepxy.x, xystart.x + stepxy.x * 2.0, xystart.x + stepxy.x * 3.0);
float4 rgba;
rgba.rgb =
get_line(xystart.y , xpos, linetaps) * columntaps.r +
get_line(xystart.y + stepxy.y , xpos, linetaps) * columntaps.g +
get_line(xystart.y + stepxy.y * 2.0, xpos, linetaps) * columntaps.b +
get_line(xystart.y + stepxy.y * 3.0, xpos, linetaps) * columntaps.a;
rgba.a = 1.0;
//-------------------------------------------------------------
//a nice quick colorspace conversion
float4 yuvx = mul(float4(rgba.rgb, 1.0), yuvMat);
return float4(saturate(yuvx.zxy), rgba.a);
}