obs-studio/build/data/libobs/format_conversion.effect

/******************************************************************************
    Copyright (C) 2014 by Hugh Bailey <[email protected]>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/

//#define DEBUGGING

uniform float4x4  ViewProj;

uniform float     u_plane_offset;
uniform float     v_plane_offset;

uniform float     width;
uniform float     height;
uniform float     width_i;
uniform float     height_i;
uniform float     width_d2;
uniform float     height_d2;
uniform float     width_d2_i;
uniform float     height_d2_i;
uniform float     input_height;

uniform texture2d image;

sampler_state def_sampler {
	Filter   = Linear;
	AddressU = Clamp;
	AddressV = Clamp;
};

struct VertInOut {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

VertInOut VSDefault(VertInOut vert_in)
{
	VertInOut vert_out;
	vert_out.pos = mul(float4(vert_in.pos.xyz, 1.0), ViewProj);
	vert_out.uv  = vert_in.uv;
	return vert_out;
}

/* used to prevent internal GPU precision issues width fmod in particular */
#define PRECISION_OFFSET 0.1

float4 PSPlanar420(VertInOut vert_in) : TARGET
{
#ifdef _OPENGL
	float v_mul = floor((1.0 - vert_in.uv.y) * input_height);
#else
	float v_mul = floor(vert_in.uv.y * input_height);
#endif

	float byte_offset = floor((v_mul + vert_in.uv.x) * width) * 4.0;
	byte_offset += PRECISION_OFFSET;

	float2 sample_pos[4];

	if (byte_offset < u_plane_offset) {
#ifdef DEBUGGING
		return float4(1.0, 1.0, 1.0, 1.0);
#endif

		float lum_u = floor(fmod(byte_offset, width)) * width_i;
		float lum_v = floor(byte_offset * width_i)    * height_i;

		/* move to texel centers to sample the 4 pixels properly */
		lum_u += width_i  * 0.5;
		lum_v += height_i * 0.5;

		sample_pos[0] = float2(lum_u,            lum_v);
		sample_pos[1] = float2(lum_u += width_i, lum_v);
		sample_pos[2] = float2(lum_u += width_i, lum_v);
		sample_pos[3] = float2(lum_u +  width_i, lum_v);

	} else {
#ifdef DEBUGGING
		return ((byte_offset < v_plane_offset) ?
				float4(0.5, 0.5, 0.5, 0.5) :
				float4(0.2, 0.2, 0.2, 0.2));
#endif

		float new_offset = byte_offset -
				((byte_offset < v_plane_offset) ?
				u_plane_offset : v_plane_offset);

		float ch_u = floor(fmod(new_offset, width_d2)) * width_d2_i;
		float ch_v = floor(new_offset * width_d2_i)    * height_d2_i;
		float width_i2 = width_i*2.0;

		/* move to the borders of each set of 4 pixels to force it
		 * to do bilinear averaging */
		ch_u += width_i;
		ch_v += height_i;

		sample_pos[0] = float2(ch_u,             ch_v);
		sample_pos[1] = float2(ch_u += width_i2, ch_v);
		sample_pos[2] = float2(ch_u += width_i2, ch_v);
		sample_pos[3] = float2(ch_u +  width_i2, ch_v);
	}

	float4x4 out_val = float4x4(
		image.Sample(def_sampler, sample_pos[0]),
		image.Sample(def_sampler, sample_pos[1]),
		image.Sample(def_sampler, sample_pos[2]),
		image.Sample(def_sampler, sample_pos[3])
	);

	out_val = transpose(out_val);

	if (byte_offset < u_plane_offset)
		return out_val[1];
	else if (byte_offset < v_plane_offset)
		return out_val[0];
	else
		return out_val[2];
}

technique Planar420
{
	pass
	{
		vertex_shader = VSDefault(vert_in);
		pixel_shader  = PSPlanar420(vert_in);
	}
}