obs-studio/libobs/data/bicubic_scale.effect

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/*
* bicubic sharper (better for downscaling)
* note - this shader is adapted from the GPL bsnes shader, very good stuff
* there.
*/
uniform float4x4 ViewProj;
uniform texture2d image;
uniform float4x4 color_matrix;
uniform float3 color_range_min = {0.0, 0.0, 0.0};
uniform float3 color_range_max = {1.0, 1.0, 1.0};
uniform float2 base_dimension_i;
sampler_state textureSampler {
Filter = Linear;
AddressU = Clamp;
AddressV = Clamp;
};
struct VertData {
float4 pos : POSITION;
float2 uv : TEXCOORD0;
};
VertData VSDefault(VertData input)
{
VertData vert_out;
vert_out.pos = mul(float4(input.pos.xyz, 1.0), ViewProj);
vert_out.uv = input.uv;
return vert_out;
}
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));
}
float4 pixel(float xpos, float ypos)
{
return image.Sample(textureSampler, float2(xpos, ypos));
}
float4 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 DrawBicubic(VertData input)
{
float2 stepxy = base_dimension_i;
float2 pos = input.uv + stepxy * 0.5;
float2 f = frac(pos / stepxy);
float4 rowtaps = weight4(1.0 - f.x);
float4 coltaps = weight4(1.0 - f.y);
/* make sure all taps added together is exactly 1.0, otherwise some
* (very small) distortion can occur */
rowtaps /= rowtaps.r + rowtaps.g + rowtaps.b + rowtaps.a;
coltaps /= coltaps.r + coltaps.g + coltaps.b + coltaps.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
);
return
get_line(xystart.y , xpos, rowtaps) * coltaps.r +
get_line(xystart.y + stepxy.y , xpos, rowtaps) * coltaps.g +
get_line(xystart.y + stepxy.y * 2.0, xpos, rowtaps) * coltaps.b +
get_line(xystart.y + stepxy.y * 3.0, xpos, rowtaps) * coltaps.a;
}
float4 PSDrawBicubicRGBA(VertData input) : TARGET
{
return DrawBicubic(input);
}
float4 PSDrawBicubicMatrix(VertData input) : TARGET
{
float4 rgba = DrawBicubic(input);
float4 yuv;
yuv.xyz = clamp(rgba.xyz, color_range_min, color_range_max);
return saturate(mul(float4(yuv.xyz, 1.0), color_matrix));
}
technique Draw
{
pass
{
vertex_shader = VSDefault(input);
pixel_shader = PSDrawBicubicRGBA(input);
}
}
technique DrawMatrix
{
pass
{
vertex_shader = VSDefault(input);
pixel_shader = PSDrawBicubicMatrix(input);
}
}