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CLK/Outputs/CRT/Internals/CRTOpenGL.cpp

607 lines
23 KiB
C++

// CRTOpenGL.cpp
// Clock Signal
//
// Created by Thomas Harte on 03/02/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "CRT.hpp"
#include <stdlib.h>
#include <math.h>
#include "CRTOpenGL.hpp"
using namespace Outputs::CRT;
namespace {
static const GLenum first_supplied_buffer_texture_unit = 3;
}
OpenGLOutputBuilder::OpenGLOutputBuilder(unsigned int buffer_depth) :
_run_write_pointer(0),
_output_mutex(new std::mutex),
_visible_area(Rect(0, 0, 1, 1)),
_composite_src_output_y(0),
_composite_shader(nullptr),
_rgb_shader(nullptr),
_output_buffer_data(nullptr),
_output_buffer_sync(nullptr),
_input_texture_data(nullptr)
{
_run_builders = new CRTRunBuilder *[NumberOfFields];
for(int builder = 0; builder < NumberOfFields; builder++)
{
_run_builders[builder] = new CRTRunBuilder();
}
// _composite_src_runs = std::unique_ptr<CRTRunBuilder>(new CRTRunBuilder(InputVertexSize));
_buffer_builder = std::unique_ptr<CRTInputBufferBuilder>(new CRTInputBufferBuilder(buffer_depth));
}
OpenGLOutputBuilder::~OpenGLOutputBuilder()
{
for(int builder = 0; builder < NumberOfFields; builder++)
{
delete _run_builders[builder];
}
delete[] _run_builders;
glUnmapBuffer(GL_ARRAY_BUFFER);
glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
glDeleteTextures(1, &textureName);
glDeleteBuffers(1, &_input_texture_array);
glDeleteBuffers(1, &output_array_buffer);
glDeleteVertexArrays(1, &output_vertex_array);
free(_composite_shader);
free(_rgb_shader);
}
static GLenum formatForDepth(size_t depth)
{
switch(depth)
{
default: return GL_FALSE;
case 1: return GL_RED;
case 2: return GL_RG;
case 3: return GL_RGB;
case 4: return GL_RGBA;
}
}
void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int output_height, bool only_if_dirty)
{
// establish essentials
if(!composite_input_shader_program && !rgb_shader_program)
{
// generate and bind texture for input data
glGenTextures(1, &textureName);
glActiveTexture(GL_TEXTURE0 + first_supplied_buffer_texture_unit);
glBindTexture(GL_TEXTURE_2D, textureName);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
GLenum format = formatForDepth(_buffer_builder->bytes_per_pixel);
glGenBuffers(1, &_input_texture_array);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, _input_texture_array);
glBufferData(GL_PIXEL_UNPACK_BUFFER, InputTextureBufferDataSize, NULL, GL_STREAM_DRAW);
glTexImage2D(GL_TEXTURE_2D, 0, (GLint)format, InputBufferBuilderWidth, InputBufferBuilderHeight, 0, format, GL_UNSIGNED_BYTE, nullptr);
prepare_composite_input_shader();
prepare_rgb_output_shader();
glGenVertexArrays(1, &output_vertex_array);
glGenBuffers(1, &output_array_buffer);
output_vertices_per_slice = 0;
glBindBuffer(GL_ARRAY_BUFFER, output_array_buffer);
glBufferData(GL_ARRAY_BUFFER, InputVertexBufferDataSize, NULL, GL_STREAM_DRAW);
_output_buffer_data_pointer = 0;
glBindVertexArray(output_vertex_array);
prepare_output_vertex_array();
// This should return either an actual framebuffer number, if this is a target with a framebuffer intended for output,
// or 0 if no framebuffer is bound, in which case 0 is also what we want to supply to bind the implied framebuffer. So
// it works either way.
glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint *)&defaultFramebuffer);
// Create intermediate textures and bind to slots 0, 1 and 2
// glActiveTexture(GL_TEXTURE0);
// compositeTexture = std::unique_ptr<OpenGL::TextureTarget>(new OpenGL::TextureTarget(IntermediateBufferWidth, IntermediateBufferHeight));
// glActiveTexture(GL_TEXTURE1);
// filteredYTexture = std::unique_ptr<OpenGL::TextureTarget>(new OpenGL::TextureTarget(IntermediateBufferWidth, IntermediateBufferHeight));
// glActiveTexture(GL_TEXTURE2);
// filteredTexture = std::unique_ptr<OpenGL::TextureTarget>(new OpenGL::TextureTarget(IntermediateBufferWidth, IntermediateBufferHeight));
}
// lock down any further work on the current frame
_output_mutex->lock();
// release the mapping, giving up on trying to draw if data has been lost
if(glUnmapBuffer(GL_ARRAY_BUFFER) == GL_FALSE)
{
for(int c = 0; c < NumberOfFields; c++)
_run_builders[c]->reset();
}
glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
// upload more source pixel data if any; we'll always resubmit the last line submitted last
// time as it may have had extra data appended to it
// for(unsigned int buffer = 0; buffer < _buffer_builder->number_of_buffers; buffer++)
// {
// glActiveTexture(GL_TEXTURE0 + first_supplied_buffer_texture_unit + buffer);
GLenum format = formatForDepth(_buffer_builder->bytes_per_pixel);
if(_buffer_builder->_next_write_y_position < _buffer_builder->last_uploaded_line)
{
glTexSubImage2D(GL_TEXTURE_2D, 0,
0, (GLint)_buffer_builder->last_uploaded_line,
InputBufferBuilderWidth, (GLint)(InputBufferBuilderHeight - _buffer_builder->last_uploaded_line),
format, GL_UNSIGNED_BYTE,
(void *)(_buffer_builder->last_uploaded_line * InputBufferBuilderWidth * _buffer_builder->bytes_per_pixel));
_buffer_builder->last_uploaded_line = 0;
}
if(_buffer_builder->_next_write_y_position > _buffer_builder->last_uploaded_line)
{
glTexSubImage2D(GL_TEXTURE_2D, 0,
0, (GLint)_buffer_builder->last_uploaded_line,
InputBufferBuilderWidth, (GLint)(1 + _buffer_builder->_next_write_y_position - _buffer_builder->last_uploaded_line),
format, GL_UNSIGNED_BYTE,
(void *)(_buffer_builder->last_uploaded_line * InputBufferBuilderWidth * _buffer_builder->bytes_per_pixel));
_buffer_builder->last_uploaded_line = _buffer_builder->_next_write_y_position;
}
// }
// check for anything to decode from composite
// if(_composite_src_runs->number_of_vertices)
// {
// composite_input_shader_program->bind();
// _composite_src_runs->reset();
// }
// _output_mutex->unlock();
// return;
// reinstate the output framebuffer
// glBindTexture(GL_TEXTURE_2D, _openGL_state->textureName);
// glGetIntegerv(GL_VIEWPORT, results);
// switch to the output shader
if(rgb_shader_program)
{
rgb_shader_program->bind();
// update uniforms
push_size_uniforms(output_width, output_height);
// Ensure we're back on the output framebuffer
glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
// clear the buffer
glClear(GL_COLOR_BUFFER_BIT);
// draw all sitting frames
unsigned int run = (unsigned int)_run_write_pointer;
GLint total_age = 0;
for(int c = 0; c < NumberOfFields; c++)
{
// update the total age at the start of this set of runs
total_age += _run_builders[run]->duration;
if(_run_builders[run]->amount_of_data > 0)
{
// draw
glUniform1f(timestampBaseUniform, (GLfloat)total_age);
GLsizei count = (GLsizei)(_run_builders[run]->amount_of_data / InputVertexSize);
GLsizei max_count = (GLsizei)((InputVertexBufferDataSize - _run_builders[run]->start) / InputVertexSize);
if(count < max_count)
{
glDrawArrays(GL_TRIANGLE_STRIP, (GLint)(_run_builders[run]->start / InputVertexSize), count);
}
else
{
glDrawArrays(GL_TRIANGLE_STRIP, (GLint)(_run_builders[run]->start / InputVertexSize), max_count);
glDrawArrays(GL_TRIANGLE_STRIP, 0, count - max_count);
}
}
// advance back in time
run = (run - 1 + NumberOfFields) % NumberOfFields;
}
}
// drawing commands having been issued, reclaim the array buffer pointer
_buffer_builder->move_to_new_line();
_output_buffer_data = (uint8_t *)glMapBufferRange(GL_ARRAY_BUFFER, 0, InputVertexBufferDataSize, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
_input_texture_data = (uint8_t *)glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, InputTextureBufferDataSize, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
_output_mutex->unlock();
}
void OpenGLOutputBuilder::set_openGL_context_will_change(bool should_delete_resources)
{
}
void OpenGLOutputBuilder::push_size_uniforms(unsigned int output_width, unsigned int output_height)
{
if(windowSizeUniform >= 0)
{
glUniform2f(windowSizeUniform, output_width, output_height);
}
GLfloat outputAspectRatioMultiplier = ((float)output_width / (float)output_height) / (4.0f / 3.0f);
Rect _aspect_ratio_corrected_bounds = _visible_area;
GLfloat bonusWidth = (outputAspectRatioMultiplier - 1.0f) * _visible_area.size.width;
_aspect_ratio_corrected_bounds.origin.x -= bonusWidth * 0.5f * _aspect_ratio_corrected_bounds.size.width;
_aspect_ratio_corrected_bounds.size.width *= outputAspectRatioMultiplier;
if(boundsOriginUniform >= 0)
glUniform2f(boundsOriginUniform, (GLfloat)_aspect_ratio_corrected_bounds.origin.x, (GLfloat)_aspect_ratio_corrected_bounds.origin.y);
if(boundsSizeUniform >= 0)
glUniform2f(boundsSizeUniform, (GLfloat)_aspect_ratio_corrected_bounds.size.width, (GLfloat)_aspect_ratio_corrected_bounds.size.height);
}
void OpenGLOutputBuilder::set_composite_sampling_function(const char *shader)
{
_composite_shader = strdup(shader);
}
void OpenGLOutputBuilder::set_rgb_sampling_function(const char *shader)
{
_rgb_shader = strdup(shader);
}
#pragma mark - Input vertex shader (i.e. from source data to intermediate line layout)
char *OpenGLOutputBuilder::get_input_vertex_shader()
{
return strdup(
"#version 150\n"
"in vec2 inputPosition;"
"in vec2 outputPosition;"
"in vec2 phaseAndAmplitude;"
"in float phaseTime;"
"uniform vec2 outputTextureSize;"
"uniform vec2 inputTextureSize;"
"uniform float phaseCyclesPerTick;"
"out vec2 inputPositionVarying;"
"out float phaseVarying;"
"void main(void)"
"{"
"inputPositionVarying = vec2(inputPositionVarying.x / inputTextureSize.x, (inputPositionVarying.y + 0.5) / inputTextureSize.y);"
"gl_Position = vec4(outputPosition.x * 2.0 / outputTextureSize - 1.0, outputPosition.y * 2.0 / outputTextureSize - 1.0, 0.0, 1.0);"
"phaseVarying = (phaseCyclesPerTick * phaseTime + phaseAndAmplitude.x) * 2.0 * 3.141592654;"
"}");
}
char *OpenGLOutputBuilder::get_input_fragment_shader()
{
const char *composite_shader = _composite_shader;
if(!composite_shader)
{
// TODO: synthesise an RGB -> (selected colour space) shader
}
return get_compound_shader(
"#version 150\n"
"in vec2 inputPositionVarying;"
"in float phaseVarying;"
"out vec4 fragColour;"
"uniform sampler2D texID;"
"\n%s\n"
"void main(void)"
"{"
"fragColour = vec4(composite_sample(inputPositionVarying, phaseVarying), 0.0, 0.0, 1.0);"
"}"
, composite_shader);
}
#pragma mark - Intermediate vertex shaders (i.e. from intermediate line layout to intermediate line layout)
#pragma mark - Output vertex shader
char *OpenGLOutputBuilder::get_output_vertex_shader()
{
// the main job of the vertex shader is just to map from an input area of [0,1]x[0,1], with the origin in the
// top left to OpenGL's [-1,1]x[-1,1] with the origin in the lower left, and to convert input data coordinates
// from integral to floating point.
return strdup(
"#version 150\n"
"in vec2 position;"
"in vec2 srcCoordinates;"
"in float lateral;"
"in float timestamp;"
"uniform vec2 boundsOrigin;"
"uniform vec2 boundsSize;"
"out float lateralVarying;"
"out vec2 shadowMaskCoordinates;"
"out float alpha;"
"uniform vec2 textureSize;"
"uniform float timestampBase;"
"uniform float ticksPerFrame;"
"uniform vec2 positionConversion;"
"uniform vec2 scanNormal;"
"const float shadowMaskMultiple = 600;"
"out vec2 srcCoordinatesVarying;"
"void main(void)"
"{"
"lateralVarying = lateral + 1.0707963267949;"
"shadowMaskCoordinates = position * vec2(shadowMaskMultiple, shadowMaskMultiple * 0.85057471264368);"
"srcCoordinatesVarying = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);"
"float age = (timestampBase - timestamp) / ticksPerFrame;"
"alpha = min(10.0 * exp(-age * 2.0), 1.0);"
"vec2 floatingPosition = (position / positionConversion) + lateral*scanNormal;"
"vec2 mappedPosition = (floatingPosition - boundsOrigin) / boundsSize;"
"gl_Position = vec4(mappedPosition.x * 2.0 - 1.0, 1.0 - mappedPosition.y * 2.0, 0.0, 1.0);"
"}");
}
#pragma mark - Output fragment shaders; RGB and from composite
char *OpenGLOutputBuilder::get_rgb_output_fragment_shader()
{
return get_output_fragment_shader(_rgb_shader);
}
char *OpenGLOutputBuilder::get_composite_output_fragment_shader()
{
return get_output_fragment_shader(
"vec4 rgb_sample(vec2 coordinate)"
"{"
"return texture(texID, coordinate);"
"}");
}
char *OpenGLOutputBuilder::get_output_fragment_shader(const char *sampling_function)
{
return get_compound_shader(
"#version 150\n"
"in float lateralVarying;"
"in float alpha;"
"in vec2 shadowMaskCoordinates;"
"in vec2 srcCoordinatesVarying;"
"out vec4 fragColour;"
"uniform sampler2D texID;"
"uniform sampler2D shadowMaskTexID;"
"\n%s\n"
"void main(void)"
"{"
"fragColour = rgb_sample(srcCoordinatesVarying) * vec4(1.0, 1.0, 1.0, alpha * sin(lateralVarying));" //
"}"
, sampling_function);
}
#pragma mark - Shader utilities
char *OpenGLOutputBuilder::get_compound_shader(const char *base, const char *insert)
{
if(!base || !insert) return nullptr;
size_t totalLength = strlen(base) + strlen(insert) + 1;
char *text = new char[totalLength];
snprintf(text, totalLength, base, insert);
return text;
}
#pragma mark - Program compilation
void OpenGLOutputBuilder::prepare_composite_input_shader()
{
char *vertex_shader = get_input_vertex_shader();
char *fragment_shader = get_input_fragment_shader();
if(vertex_shader && fragment_shader)
{
composite_input_shader_program = std::unique_ptr<OpenGL::Shader>(new OpenGL::Shader(vertex_shader, fragment_shader));
GLint texIDUniform = composite_input_shader_program->get_uniform_location("texID");
GLint inputTextureSizeUniform = composite_input_shader_program->get_uniform_location("inputTextureSize");
GLint outputTextureSizeUniform = composite_input_shader_program->get_uniform_location("outputTextureSize");
GLint phaseCyclesPerTickUniform = composite_input_shader_program->get_uniform_location("phaseCyclesPerTick");
glUniform1i(texIDUniform, first_supplied_buffer_texture_unit);
glUniform2f(outputTextureSizeUniform, IntermediateBufferWidth, IntermediateBufferHeight);
glUniform2f(inputTextureSizeUniform, InputBufferBuilderWidth, InputBufferBuilderHeight);
glUniform1f(phaseCyclesPerTickUniform, (float)_colour_cycle_numerator / (float)(_colour_cycle_denominator * _cycles_per_line));
}
free(vertex_shader);
free(fragment_shader);
}
/*void OpenGLOutputBuilder::prepare_output_shader(char *fragment_shader)
{
char *vertex_shader = get_output_vertex_shader();
if(vertex_shader && fragment_shader)
{
_openGL_state->rgb_shader_program = std::unique_ptr<OpenGL::Shader>(new OpenGL::Shader(vertex_shader, fragment_shader));
_openGL_state->rgb_shader_program->bind();
_openGL_state->windowSizeUniform = _openGL_state->rgb_shader_program->get_uniform_location("windowSize");
_openGL_state->boundsSizeUniform = _openGL_state->rgb_shader_program->get_uniform_location("boundsSize");
_openGL_state->boundsOriginUniform = _openGL_state->rgb_shader_program->get_uniform_location("boundsOrigin");
_openGL_state->timestampBaseUniform = _openGL_state->rgb_shader_program->get_uniform_location("timestampBase");
GLint texIDUniform = _openGL_state->rgb_shader_program->get_uniform_location("texID");
GLint shadowMaskTexIDUniform = _openGL_state->rgb_shader_program->get_uniform_location("shadowMaskTexID");
GLint textureSizeUniform = _openGL_state->rgb_shader_program->get_uniform_location("textureSize");
GLint ticksPerFrameUniform = _openGL_state->rgb_shader_program->get_uniform_location("ticksPerFrame");
GLint scanNormalUniform = _openGL_state->rgb_shader_program->get_uniform_location("scanNormal");
GLint positionConversionUniform = _openGL_state->rgb_shader_program->get_uniform_location("positionConversion");
glUniform1i(texIDUniform, first_supplied_buffer_texture_unit);
glUniform1i(shadowMaskTexIDUniform, 1);
glUniform2f(textureSizeUniform, CRTInputBufferBuilderWidth, CRTInputBufferBuilderHeight);
glUniform1f(ticksPerFrameUniform, (GLfloat)(_cycles_per_line * _height_of_display));
glUniform2f(positionConversionUniform, _horizontal_flywheel->get_scan_period(), _vertical_flywheel->get_scan_period() / (unsigned int)_vertical_flywheel_output_divider);
float scan_angle = atan2f(1.0f / (float)_height_of_display, 1.0f);
float scan_normal[] = { -sinf(scan_angle), cosf(scan_angle)};
float multiplier = (float)_horizontal_flywheel->get_standard_period() / ((float)_height_of_display * (float)_horizontal_flywheel->get_scan_period());
scan_normal[0] *= multiplier;
scan_normal[1] *= multiplier;
glUniform2f(scanNormalUniform, scan_normal[0], scan_normal[1]);
}
free(vertex_shader);
free(fragment_shader);
}*/
void OpenGLOutputBuilder::prepare_rgb_output_shader()
{
char *vertex_shader = get_output_vertex_shader();
char *fragment_shader = get_rgb_output_fragment_shader();
if(vertex_shader && fragment_shader)
{
rgb_shader_program = std::unique_ptr<OpenGL::Shader>(new OpenGL::Shader(vertex_shader, fragment_shader));
rgb_shader_program->bind();
windowSizeUniform = rgb_shader_program->get_uniform_location("windowSize");
boundsSizeUniform = rgb_shader_program->get_uniform_location("boundsSize");
boundsOriginUniform = rgb_shader_program->get_uniform_location("boundsOrigin");
timestampBaseUniform = rgb_shader_program->get_uniform_location("timestampBase");
GLint texIDUniform = rgb_shader_program->get_uniform_location("texID");
GLint shadowMaskTexIDUniform = rgb_shader_program->get_uniform_location("shadowMaskTexID");
GLint textureSizeUniform = rgb_shader_program->get_uniform_location("textureSize");
GLint ticksPerFrameUniform = rgb_shader_program->get_uniform_location("ticksPerFrame");
GLint scanNormalUniform = rgb_shader_program->get_uniform_location("scanNormal");
GLint positionConversionUniform = rgb_shader_program->get_uniform_location("positionConversion");
glUniform1i(texIDUniform, first_supplied_buffer_texture_unit);
glUniform1i(shadowMaskTexIDUniform, 1);
glUniform2f(textureSizeUniform, InputBufferBuilderWidth, InputBufferBuilderHeight);
glUniform1f(ticksPerFrameUniform, (GLfloat)(_cycles_per_line * _height_of_display));
glUniform2f(positionConversionUniform, _horizontal_scan_period, _vertical_scan_period / (unsigned int)_vertical_period_divider);
float scan_angle = atan2f(1.0f / (float)_height_of_display, 1.0f);
float scan_normal[] = { -sinf(scan_angle), cosf(scan_angle)};
float multiplier = (float)_cycles_per_line / ((float)_height_of_display * (float)_horizontal_scan_period);
scan_normal[0] *= multiplier;
scan_normal[1] *= multiplier;
glUniform2f(scanNormalUniform, scan_normal[0], scan_normal[1]);
}
free(vertex_shader);
free(fragment_shader);
}
void OpenGLOutputBuilder::prepare_output_vertex_array()
{
if(rgb_shader_program)
{
GLint positionAttribute = rgb_shader_program->get_attrib_location("position");
GLint textureCoordinatesAttribute = rgb_shader_program->get_attrib_location("srcCoordinates");
GLint lateralAttribute = rgb_shader_program->get_attrib_location("lateral");
GLint timestampAttribute = rgb_shader_program->get_attrib_location("timestamp");
glEnableVertexAttribArray((GLuint)positionAttribute);
glEnableVertexAttribArray((GLuint)textureCoordinatesAttribute);
glEnableVertexAttribArray((GLuint)lateralAttribute);
glEnableVertexAttribArray((GLuint)timestampAttribute);
const GLsizei vertexStride = OutputVertexSize;
glVertexAttribPointer((GLuint)positionAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)OutputVertexOffsetOfPosition);
glVertexAttribPointer((GLuint)textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT, GL_FALSE, vertexStride, (void *)OutputVertexOffsetOfTexCoord);
glVertexAttribPointer((GLuint)timestampAttribute, 4, GL_UNSIGNED_INT, GL_FALSE, vertexStride, (void *)OutputVertexOffsetOfTimestamp);
glVertexAttribPointer((GLuint)lateralAttribute, 1, GL_UNSIGNED_BYTE, GL_FALSE, vertexStride, (void *)OutputVertexOffsetOfLateral);
}
}
#pragma mark - Configuration
void OpenGLOutputBuilder::set_output_device(OutputDevice output_device)
{
if (_output_device != output_device)
{
_output_device = output_device;
// for(int builder = 0; builder < NumberOfFields; builder++)
// {
// _run_builders[builder]->reset();
// }
// _composite_src_runs->reset();
_composite_src_output_y = 0;
}
}
// const char *const ntscVertexShaderGlobals =
// "out vec2 srcCoordinatesVarying[4];\n"
// "out float phase;\n";
//
// const char *const ntscVertexShaderBody =
// "phase = srcCoordinates.x * 6.283185308;\n"
// "\n"
// "srcCoordinatesVarying[0] = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);\n"
// "srcCoordinatesVarying[3] = srcCoordinatesVarying[0] + vec2(0.375 / textureSize.x, 0.0);\n"
// "srcCoordinatesVarying[2] = srcCoordinatesVarying[0] + vec2(0.125 / textureSize.x, 0.0);\n"
// "srcCoordinatesVarying[1] = srcCoordinatesVarying[0] - vec2(0.125 / textureSize.x, 0.0);\n"
// "srcCoordinatesVarying[0] = srcCoordinatesVarying[0] - vec2(0.325 / textureSize.x, 0.0);\n";
// assumes y = [0, 1], i and q = [-0.5, 0.5]; therefore i components are multiplied by 1.1914 versus standard matrices, q by 1.0452
// const char *const yiqToRGB = "const mat3 yiqToRGB = mat3(1.0, 1.0, 1.0, 1.1389784, -0.3240608, -1.3176884, 0.6490692, -0.6762444, 1.7799756);";
// assumes y = [0,1], u and v = [-0.5, 0.5]; therefore u components are multiplied by 1.14678899082569, v by 0.8130081300813
// const char *const yuvToRGB = "const mat3 yiqToRGB = mat3(1.0, 1.0, 1.0, 0.0, -0.75213899082569, 2.33040137614679, 0.92669105691057, -0.4720325203252, 0.0);";
// const char *const ntscFragmentShaderGlobals =
// "in vec2 srcCoordinatesVarying[4];\n"
// "in float phase;\n"
// "\n"
// "// for conversion from i and q are in the range [-0.5, 0.5] (so i needs to be multiplied by 1.1914 and q by 1.0452)\n"
// "const mat3 yiqToRGB = mat3(1.0, 1.0, 1.0, 1.1389784, -0.3240608, -1.3176884, 0.6490692, -0.6762444, 1.7799756);\n";
// const char *const ntscFragmentShaderBody =
// "vec4 angles = vec4(phase) + vec4(-2.35619449019234, -0.78539816339745, 0.78539816339745, 2.35619449019234);\n"
// "vec4 samples = vec4("
// " sample(srcCoordinatesVarying[0], angles.x),"
// " sample(srcCoordinatesVarying[1], angles.y),"
// " sample(srcCoordinatesVarying[2], angles.z),"
// " sample(srcCoordinatesVarying[3], angles.w)"
// ");\n"
// "\n"
// "float y = dot(vec4(0.25), samples);\n"
// "samples -= vec4(y);\n"
// "\n"
// "float i = dot(cos(angles), samples);\n"
// "float q = dot(sin(angles), samples);\n"
// "\n"
// "fragColour = 5.0 * texture(shadowMaskTexID, shadowMaskCoordinates) * vec4(yiqToRGB * vec3(y, i, q), 1.0);//sin(lateralVarying));\n";
// dot(vec3(1.0/6.0, 2.0/3.0, 1.0/6.0), vec3(sample(srcCoordinatesVarying[0]), sample(srcCoordinatesVarying[0]), sample(srcCoordinatesVarying[0])));//sin(lateralVarying));\n";
//}