obs-studio/libobs/data/bilinear_lowres_scale.effect
James Park 69c215345a libobs: Simplify YUV conversion
Currently several shaders need "DrawMatrix" techniques to support the
possibility that the input texture is a "YUV" format. Also, "DrawMatrix"
is overloaded for translation in both directions when it is written for
RGB to "YUV" only.

A cleaner solution is to handle "YUV" to RGB up-front as part of format
conversion, and ensure only RGB inputs reach the other shaders. This is
necessary to someday perform correct scale filtering without the cost of
redundant "YUV" conversions per texture tap.

A necessary prerequisite for this is to add conversion support for
VIDEO_FORMAT_I444, and that is now in place. There was already a hack in
place to cover VIDEO_FORMAT_Y800. All other "YUV" formats already have
conversion functions.

"DrawMatrix" has been removed from shaders that only supported "YUV" to
RGB conversions. It still exists in shaders that perform RGB to "YUV"
conversions, and the implementations have been sanitized accordingly.
2019-04-11 23:00:03 -07:00

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/*
* bilinear low res scaling, samples 9 pixels of a larger image to scale to a
* low resolution image below half size
*/
uniform float4x4 ViewProj;
uniform texture2d image;
uniform float4x4 color_matrix;
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 v_in)
{
VertData vert_out;
vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
vert_out.uv = v_in.uv;
return vert_out;
}
float4 pixel(float2 uv)
{
return image.Sample(textureSampler, uv);
}
float4 DrawLowresBilinear(VertData v_in)
{
float2 stepxy = base_dimension_i;
float4 out_color;
out_color = pixel(v_in.uv);
out_color += pixel(v_in.uv + float2(-stepxy.x, -stepxy.y));
out_color += pixel(v_in.uv + float2(-stepxy.x, 0.0));
out_color += pixel(v_in.uv + float2(-stepxy.x, stepxy.y));
out_color += pixel(v_in.uv + float2( 0.0, -stepxy.y));
out_color += pixel(v_in.uv + float2( 0.0, stepxy.y));
out_color += pixel(v_in.uv + float2( stepxy.x, -stepxy.y));
out_color += pixel(v_in.uv + float2( stepxy.x, 0.0));
out_color += pixel(v_in.uv + float2( stepxy.x, stepxy.y));
return out_color / float4(9.0, 9.0, 9.0, 9.0);
}
float4 PSDrawLowresBilinearRGBA(VertData v_in) : TARGET
{
return DrawLowresBilinear(v_in);
}
float4 PSDrawLowresBilinearMatrix(VertData v_in) : TARGET
{
float3 rgb = DrawLowresBilinear(v_in);
float3 yuv = mul(float4(saturate(rgb), 1.0), color_matrix).xyz;
return float4(yuv, 1.0);
}
technique Draw
{
pass
{
vertex_shader = VSDefault(v_in);
pixel_shader = PSDrawLowresBilinearRGBA(v_in);
}
}
technique DrawMatrix
{
pass
{
vertex_shader = VSDefault(v_in);
pixel_shader = PSDrawLowresBilinearMatrix(v_in);
}
}