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https://github.com/TomHarte/CLK.git
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359 lines
9.8 KiB
C++
359 lines
9.8 KiB
C++
//
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// KernelShaders.cpp
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// Clock Signal Kiosk
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//
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// Created by Thomas Harte on 03/02/2026.
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// Copyright © 2026 Thomas Harte. All rights reserved.
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//
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#include "KernelShaders.hpp"
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#include "CommonAtrributes.hpp"
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#include "DirtyZone.hpp"
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#include "Outputs/ScanTargets/FilterGenerator.hpp"
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#include <cstring>
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namespace {
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constexpr char vertex_shader[] = R"glsl(
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uniform float samplesPerLine;
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uniform vec2 bufferSize;
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in float zoneBegin;
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in float zoneEnd;
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#ifdef USES_COORDINATES
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out vec2 coordinates[11];
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#endif
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void main(void) {
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float lateral = float(gl_VertexID & 1);
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float longitudinal = float((gl_VertexID & 2) >> 1);
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float sampleY = bufferSize.y - mix(zoneBegin, zoneEnd, longitudinal);
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float centreX = lateral * samplesPerLine;
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// Factors here:
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//
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// (1) only 8 vec4 varyings are guaranteed to exist, which can be utilised as 16 vec2s.
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// So there aren't enough to guarantee one varying per sample location;
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// (2) the cost of dependent reads is negligible nowadays unless and until it obviates
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// the cache.
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//
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// So the coordinates picked are a spread across the area being sampled to provide enough
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// information that the GPU should be able to cache efficiently.
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#ifdef USES_COORDINATES
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coordinates[0] = vec2(centreX - 14.0, sampleY) / bufferSize; // for 15, 14, 13 [0, 1, 2]
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coordinates[1] = vec2(centreX - 11.0, sampleY) / bufferSize; // for 12, 11, 10 [3, 4, 5]
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coordinates[2] = vec2(centreX - 8.0, sampleY) / bufferSize; // for 9, 8, 7 [6, 7, 8]
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coordinates[3] = vec2(centreX - 5.0, sampleY) / bufferSize; // for 6, 5, 4 [9, 10, 11]
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coordinates[4] = vec2(centreX - 2.0, sampleY) / bufferSize; // for 3, 2, 1 [12, 13, 14]
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coordinates[5] = vec2(centreX + 0.0, sampleY) / bufferSize; // Centre. [15]
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coordinates[6] = vec2(centreX + 2.0, sampleY) / bufferSize; // 1, 2, 3 [16, 17, 18]
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coordinates[7] = vec2(centreX + 5.0, sampleY) / bufferSize; // 4, 5, 6 [19, 20, 21]
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coordinates[8] = vec2(centreX + 8.0, sampleY) / bufferSize; // 7, 8, 9 [22, 23, 24]
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coordinates[9] = vec2(centreX + 11.0, sampleY) / bufferSize; // 10, 11, 12 [25, 26, 27]
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coordinates[10] = vec2(centreX + 14.0, sampleY) / bufferSize; // 13, 14, 15 [28, 29, 30]
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#endif
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gl_Position = vec4(
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(vec2(centreX, sampleY) / bufferSize - vec2(0.5)) * vec2(2.0),
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0.0,
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1.0
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);
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}
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)glsl";
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constexpr char coordinate_indexer[] = R"glsl(
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#define KernelCentre 15
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in vec2 coordinates[11];
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uniform vec2 bufferSize;
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#define offset(i) ((float(i) - 15.0) / bufferSize.x)
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#define coordinate(i) (\
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(i) == 1 ? coordinates[0] : \
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(i) == 4 ? coordinates[1] : \
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(i) == 7 ? coordinates[2] : \
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(i) == 10 ? coordinates[3] : \
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(i) == 13 ? coordinates[4] : \
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(i) == 15 ? coordinates[5] : \
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(i) == 17 ? coordinates[6] : \
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(i) == 20 ? coordinates[7] : \
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(i) == 23 ? coordinates[8] : \
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(i) == 26 ? coordinates[9] : \
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(i) == 29 ? coordinates[10] : \
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coordinates[5] + vec2(offset(i), 0.0) \
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)
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#define coefficient(x) filterCoefficients[x > KernelCentre ? KernelCentre - (x - KernelCentre) : x]
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)glsl";
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constexpr char separation_fragment_shader[] = R"glsl(
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uniform sampler2D source;
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uniform vec2 filterCoefficients[16];
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out vec4 outputColour;
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void main(void) {
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vec4 centre = texture(source, coordinate(15));
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#define Sample(x) texture(source, coordinate(x)).r * coefficient(x)
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vec2 channels =
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Sample(0) + Sample(1) + Sample(2) + Sample(3) +
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Sample(4) + Sample(5) + Sample(6) + Sample(7) +
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Sample(8) + Sample(9) + Sample(10) + Sample(11) +
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Sample(12) + Sample(13) + Sample(14) +
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filterCoefficients[15] * centre.x +
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Sample(16) + Sample(17) + Sample(18) +
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Sample(19) + Sample(20) + Sample(21) + Sample(22) +
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Sample(23) + Sample(24) + Sample(25) + Sample(26) +
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Sample(27) + Sample(28) + Sample(29) + Sample(30);
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#undef Sample
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float colourAmplitude = centre.a;
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float isColour = step(0.01, colourAmplitude);
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float chromaScale = mix(1.0, colourAmplitude, isColour);
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float lumaScale = mix(1.0, 1.0 - colourAmplitude * 2.0, isColour);
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outputColour = vec4(
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(channels.x - colourAmplitude) / lumaScale,
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isColour * channels.y * (centre.yz / chromaScale) + vec2(0.5),
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1.0
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);
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}
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)glsl";
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constexpr char demodulation_fragment_shader[] = R"glsl(
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uniform sampler2D source;
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uniform vec3 filterCoefficients[16];
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uniform mat3 toRGB;
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out vec4 outputColour;
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void main(void) {
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vec4 centre = texture(source, coordinate(15));
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#define Sample(x) (texture(source, coordinate(x)).rgb - vec3(0.0, 0.5, 0.5)) * coefficient(x)
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vec3 channels =
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Sample(0) + Sample(1) + Sample(2) + Sample(3) +
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Sample(4) + Sample(5) + Sample(6) + Sample(7) +
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Sample(8) + Sample(9) + Sample(10) + Sample(11) +
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Sample(12) + Sample(13) + Sample(14) +
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filterCoefficients[15] * (centre.rgb - vec3(0.0, 0.5, 0.5)) +
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Sample(16) + Sample(17) + Sample(18) +
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Sample(19) + Sample(20) + Sample(21) + Sample(22) +
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Sample(23) + Sample(24) + Sample(25) + Sample(26) +
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Sample(27) + Sample(28) + Sample(29) + Sample(30);
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#undef Sample
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outputColour = vec4(
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toRGB * channels,
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1.0
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);
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}
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)glsl";
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constexpr char fill_fragment_shader[] = R"glsl(
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uniform vec4 colour;
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out vec4 outputColour;
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void main(void) {
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outputColour = colour;
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}
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)glsl";
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}
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using namespace Outputs::Display;
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namespace {
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void enable_vertex_attributes(
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OpenGL::Shader &shader,
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const OpenGL::VertexArray &vertex_array
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) {
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OpenGL::DirtyZone zone;
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vertex_array.bind_all();
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const auto enable = [&](const std::string &name, uint16_t &element) {
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shader.enable_vertex_attribute_with_pointer(
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name,
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1,
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GL_UNSIGNED_SHORT,
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GL_FALSE,
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sizeof(zone),
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reinterpret_cast<void *>((reinterpret_cast<uint8_t *>(&element) - reinterpret_cast<uint8_t *>(&zone))),
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1
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);
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};
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enable("zoneBegin", zone.begin);
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enable("zoneEnd", zone.end);
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}
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template <size_t> struct FilterElement;
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template <> struct FilterElement<2> {
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void set_luma(const float luma) { x = luma; }
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void set_chroma(const float chroma) { y = chroma; }
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float x, y;
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};
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template <> struct FilterElement<3> {
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void set_luma(const float luma) { x = luma; }
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void set_chroma(const float chroma) { y = z = chroma; }
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float x, y, z;
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};
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void set_size_uniforms(
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OpenGL::Shader &shader,
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const int samples_per_line,
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const int buffer_width,
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const int buffer_height
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) {
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shader.set_uniform("samplesPerLine", float(samples_per_line));
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shader.set_uniform("bufferSize", float(buffer_width), float(buffer_height));
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}
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template <size_t FilterSize>
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void set_filter_uniforms(
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OpenGL::Shader &shader,
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const int samples_per_line,
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const int buffer_width,
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const int buffer_height,
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const GLenum source_texture_unit,
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const FilterGenerator::FilterPair filter
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) {
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set_size_uniforms(shader, samples_per_line, buffer_width, buffer_height);
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shader.set_uniform("source", GLint(source_texture_unit - GL_TEXTURE0));
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// Zip and provide the filter coefficients.
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static_assert(FilterGenerator::MaxKernelSize <= 31);
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FilterElement<FilterSize> elements[31]{};
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filter.luma.copy_to(std::begin(elements), std::end(elements),
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[](const auto iterator, const float coefficient) {
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iterator->set_luma(coefficient);
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}
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);
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filter.chroma.copy_to(std::begin(elements), std::end(elements),
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[](const auto iterator, const float coefficient) {
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iterator->set_chroma(coefficient);
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}
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);
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float packaged_elements[31 * FilterSize];
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static_assert(sizeof(packaged_elements) == sizeof(elements));
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std::memcpy(packaged_elements, elements, sizeof(elements));
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shader.set_uniform("filterCoefficients", FilterSize, 16, packaged_elements);
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}
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}
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OpenGL::Shader OpenGL::separation_shader(
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const OpenGL::API api,
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const float per_line_subcarrier_frequency,
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const int samples_per_line,
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const int buffer_width,
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const int buffer_height,
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const VertexArray &vertex_array,
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const GLenum source_texture_unit
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) {
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auto shader = OpenGL::Shader(
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api,
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std::string("#define USES_COORDINATES\n") + vertex_shader,
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std::string(coordinate_indexer) + separation_fragment_shader,
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dirty_zone_attributes()
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);
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enable_vertex_attributes(shader, vertex_array);
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set_filter_uniforms<2>(
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shader,
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samples_per_line,
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buffer_width,
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buffer_height,
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source_texture_unit,
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FilterGenerator(
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samples_per_line,
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per_line_subcarrier_frequency,
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FilterGenerator::DecodingPath::Composite
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).separation_filter()
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);
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return shader;
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}
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OpenGL::Shader OpenGL::demodulation_shader(
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const OpenGL::API api,
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const ColourSpace colour_space,
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const DisplayType display_type,
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const float per_line_subcarrier_frequency,
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const int samples_per_line,
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const int buffer_width,
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const int buffer_height,
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const VertexArray &vertex_array,
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const GLenum source_texture_unit
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) {
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auto shader = OpenGL::Shader(
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api,
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std::string("#define USES_COORDINATES\n") + vertex_shader,
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std::string(coordinate_indexer) + demodulation_fragment_shader,
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dirty_zone_attributes()
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);
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enable_vertex_attributes(shader, vertex_array);
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set_filter_uniforms<3>(
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shader,
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samples_per_line,
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buffer_width,
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buffer_height,
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source_texture_unit,
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FilterGenerator(
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samples_per_line,
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per_line_subcarrier_frequency,
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is_composite(display_type) ?
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FilterGenerator::DecodingPath::Composite :
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FilterGenerator::DecodingPath::SVideo
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).demouldation_filter()
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);
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shader.set_uniform_matrix("toRGB", 3, false, to_rgb_matrix(colour_space).data());
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return shader;
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}
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OpenGL::FillShader::FillShader(
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const API api,
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const int samples_per_line,
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const int buffer_width,
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const int buffer_height,
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const VertexArray &vertex_array
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) {
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shader_ = OpenGL::Shader(
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api,
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vertex_shader,
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fill_fragment_shader,
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dirty_zone_attributes()
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);
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enable_vertex_attributes(shader_, vertex_array);
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set_size_uniforms(shader_, samples_per_line, buffer_width, buffer_height);
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}
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void OpenGL::FillShader::bind(const float r, const float g, const float b, const float a) {
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shader_.bind();
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if(colour_[0] != r || colour_[1] != g || colour_[2] != b || colour_[3] != a) {
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colour_[0] = r;
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colour_[1] = g;
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colour_[2] = b;
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colour_[3] = a;
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shader_.set_uniform("colour", r, g, b, a);
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}
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}
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