obs-studio/libobs/data/lanczos_scale.effect

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/*
* lanczos sharper
* 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;
uniform float undistort_factor = 1.0;
sampler_state textureSampler
{
AddressU = Clamp;
AddressV = Clamp;
Filter = Linear;
};
struct VertData {
float4 pos : POSITION;
float2 uv : TEXCOORD0;
};
struct FragData {
float4 pos : POSITION;
float2 uv : TEXCOORD0;
float2 scale : TEXCOORD1;
};
FragData VSDefault(VertData v_in)
{
FragData vert_out;
vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
vert_out.uv = v_in.uv;
vert_out.scale = min(0.25 + abs(0.75 / mul(float4(1.0 / base_dimension_i.xy, 1.0, 1.0), ViewProj).xy), 1.0);
return vert_out;
}
float sinc(float x)
{
const float PIval = 3.1415926535897932384626433832795;
return sin(x * PIval) / (x * PIval);
}
float weight(float x, float radius)
{
float ax = abs(x);
if (x == 0.0)
return 1.0;
else if (ax < radius)
return sinc(x) * sinc(x / radius);
else
return 0.0;
}
float3 weight3(float x, float scale)
{
return float3(
weight((x * 2.0 + 0.0 * 2.0 - 3.0) * scale, 3.0),
weight((x * 2.0 + 1.0 * 2.0 - 3.0) * scale, 3.0),
weight((x * 2.0 + 2.0 * 2.0 - 3.0) * scale, 3.0));
}
float AspectUndistortX(float x, float a)
{
// The higher the power, the longer the linear part will be.
return (1.0 - a) * (x * x * x * x * x) + a * x;
}
float AspectUndistortU(float u)
{
// Normalize texture coord to -1.0 to 1.0 range, and back.
return AspectUndistortX((u - 0.5) * 2.0, undistort_factor) * 0.5 + 0.5;
}
float2 pixel_coord(float xpos, float ypos)
{
return float2(AspectUndistortU(xpos), ypos);
}
float4 pixel(float xpos, float ypos, bool undistort)
{
if (undistort)
return image.Sample(textureSampler, pixel_coord(xpos, ypos));
else
return image.Sample(textureSampler, float2(xpos, ypos));
}
float4 get_line(float ypos, float3 xpos1, float3 xpos2, float3 rowtap1,
float3 rowtap2, bool undistort)
{
return
pixel(xpos1.r, ypos, undistort) * rowtap1.r +
pixel(xpos1.g, ypos, undistort) * rowtap2.r +
pixel(xpos1.b, ypos, undistort) * rowtap1.g +
pixel(xpos2.r, ypos, undistort) * rowtap2.g +
pixel(xpos2.g, ypos, undistort) * rowtap1.b +
pixel(xpos2.b, ypos, undistort) * rowtap2.b;
}
float4 DrawLanczos(FragData v_in, bool undistort)
{
float2 stepxy = base_dimension_i;
float2 pos = v_in.uv + stepxy * 0.5;
float2 f = frac(pos / stepxy);
float3 rowtap1 = weight3((1.0 - f.x) / 2.0, v_in.scale.x);
float3 rowtap2 = weight3((1.0 - f.x) / 2.0 + 0.5, v_in.scale.x);
float3 coltap1 = weight3((1.0 - f.y) / 2.0, v_in.scale.y);
float3 coltap2 = weight3((1.0 - f.y) / 2.0 + 0.5, v_in.scale.y);
/* make sure all taps added together is exactly 1.0, otherwise some
* (very small) distortion can occur */
float suml = rowtap1.r + rowtap1.g + rowtap1.b + rowtap2.r + rowtap2.g + rowtap2.b;
float sumc = coltap1.r + coltap1.g + coltap1.b + coltap2.r + coltap2.g + coltap2.b;
rowtap1 /= suml;
rowtap2 /= suml;
coltap1 /= sumc;
coltap2 /= sumc;
float2 xystart = (-2.5 - f) * stepxy + pos;
float3 xpos1 = float3(xystart.x , xystart.x + stepxy.x , xystart.x + stepxy.x * 2.0);
float3 xpos2 = float3(xystart.x + stepxy.x * 3.0, xystart.x + stepxy.x * 4.0, xystart.x + stepxy.x * 5.0);
return
get_line(xystart.y , xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap1.r +
get_line(xystart.y + stepxy.y , xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap2.r +
get_line(xystart.y + stepxy.y * 2.0, xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap1.g +
get_line(xystart.y + stepxy.y * 3.0, xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap2.g +
get_line(xystart.y + stepxy.y * 4.0, xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap1.b +
get_line(xystart.y + stepxy.y * 5.0, xpos1, xpos2, rowtap1, rowtap2, undistort) * coltap2.b;
}
float4 PSDrawLanczosRGBA(FragData v_in, bool undistort) : TARGET
{
return DrawLanczos(v_in, undistort);
}
float4 PSDrawLanczosMatrix(FragData v_in) : TARGET
{
float4 rgba = DrawLanczos(v_in, false);
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(v_in);
pixel_shader = PSDrawLanczosRGBA(v_in, false);
}
}
technique DrawUndistort
{
pass
{
vertex_shader = VSDefault(v_in);
pixel_shader = PSDrawLanczosRGBA(v_in, true);
}
}
technique DrawMatrix
{
pass
{
vertex_shader = VSDefault(v_in);
pixel_shader = PSDrawLanczosMatrix(v_in);
}
}