mirror of
https://github.com/RetroDECK/Duckstation.git
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84 lines
2.9 KiB
HLSL
84 lines
2.9 KiB
HLSL
#ifndef _DOWNSAMPLING_FUNCTIONS_H
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#define _DOWNSAMPLING_FUNCTIONS_H
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///////////////////////////////// MIT LICENSE ////////////////////////////////
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// Copyright (C) 2020 Alex Gunter <akg7634@gmail.com>
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal in the Software without restriction, including without limitation the
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// sell copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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float3 opaque_linear_downsample(
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const sampler2D tex,
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const float2 texcoord,
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const uint num_pairs,
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const float2 delta_uv
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) {
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const uint total_num_samples = num_pairs * 2 + 1;
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const float2 coord_left = texcoord - delta_uv * num_pairs;
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float3 acc = 0;
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for(int i = 0; i < total_num_samples; i++) {
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const float2 coord = coord_left + i * delta_uv;
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acc += tex2D_nograd(tex, coord).rgb;
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}
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return acc / total_num_samples;
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}
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float3 opaque_lanczos_downsample(
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const sampler2D tex,
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const float2 texcoord,
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const uint num_pairs,
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const float2 delta_uv,
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const float num_sinc_lobes,
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const float weight_at_center
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) {
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const uint total_num_samples = num_pairs * 2 + 1;
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const float2 coord_left = texcoord - delta_uv * num_pairs;
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const float sinc_dx = num_sinc_lobes / num_pairs; // 2 * num_sinc_lobes / (total_num_samples - 1)
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float3 acc = 0;
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float w_sum = 0;
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for(int i = 0; i < total_num_samples; i++) {
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const float2 coord = coord_left + i * delta_uv;
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const float sinc_x = i * sinc_dx;
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const float weight = (i != num_pairs) ?
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num_sinc_lobes * sin(pi*sinc_x) * sin(pi*sinc_x/num_sinc_lobes) / (pi*pi * sinc_x*sinc_x) :
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weight_at_center;
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acc += weight * tex2D_nograd(tex, coord).rgb;
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w_sum += weight;
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}
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return acc / w_sum;
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}
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float3 opaque_lanczos_downsample(
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const sampler2D tex,
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const float2 texcoord,
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const uint num_pairs,
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const float2 delta_uv,
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const float num_sinc_lobes
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) {
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return opaque_lanczos_downsample(tex, texcoord, num_pairs, delta_uv, num_sinc_lobes, 1);
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}
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#endif // _DOWNSAMPLING_FUNCTIONS_H |