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126 lines
2.9 KiB
C++
126 lines
2.9 KiB
C++
//
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// LineOutputShader.cpp
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// Clock Signal Kiosk
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//
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// Created by Thomas Harte on 04/02/2026.
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// Copyright © 2026 Thomas Harte. All rights reserved.
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//
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#include "LineOutputShader.hpp"
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#include "CommonAtrributes.hpp"
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#include "Outputs/ScanTargets/BufferingScanTarget.hpp"
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namespace {
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constexpr char vertex_shader[] = R"glsl(
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uniform mediump vec2 sourceSize;
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uniform highp vec2 positionScale;
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uniform mediump float lineHeight;
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// TODO: programmable crop should affect scaling via uniforms.
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in highp vec2 lineEndpoint0Position;
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in highp float lineEndpoint0CyclesSinceRetrace;
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in highp vec2 lineEndpoint1Position;
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in highp float lineEndpoint1CyclesSinceRetrace;
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in highp float lineLine;
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out mediump vec2 coordinate;
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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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coordinate = vec2(
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mix(
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0.0, //lineEndpoint0CyclesSinceRetrace,
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sourceSize.x, //lineEndpoint1CyclesSinceRetrace,
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lateral
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),
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lineLine + 0.5
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) / sourceSize;
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vec2 tangent = normalize(lineEndpoint1Position - lineEndpoint0Position);
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vec2 normal = vec2(tangent.y, -tangent.x);
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vec2 centre =
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mix(
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lineEndpoint0Position,
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lineEndpoint1Position,
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lateral
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) / positionScale;
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gl_Position =
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vec4(
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centre + (longitudinal - 0.5) * normal * lineHeight,
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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 fragment_shader[] = R"glsl(
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uniform lowp sampler2D source;
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in mediump vec2 coordinate;
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out lowp vec4 outputColour;
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void main(void) {
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outputColour = texture(source, coordinate);
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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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OpenGL::Shader OpenGL::line_output_shader(
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const API api,
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const int source_width,
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const int source_height,
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const int expected_vertical_lines,
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const int scale_x,
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const int scale_y,
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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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vertex_shader,
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fragment_shader,
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line_attributes()
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);
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BufferingScanTarget::Line line;
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vertex_array.bind_all();
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const auto enable = [&](const std::string &name, uint16_t &element, const GLint size) {
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shader.enable_vertex_attribute_with_pointer(
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name,
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size,
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GL_UNSIGNED_SHORT,
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GL_FALSE,
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sizeof(line),
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reinterpret_cast<void *>((reinterpret_cast<uint8_t *>(&element) - reinterpret_cast<uint8_t *>(&line))),
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1
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);
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};
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enable("lineEndpoint0Position", line.end_points[0].x, 2);
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enable("lineEndpoint1Position", line.end_points[1].x, 2);
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enable("lineEndpoint0CyclesSinceRetrace", line.end_points[0].cycles_since_end_of_horizontal_retrace, 1);
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enable("lineEndpoin10CyclesSinceRetrace", line.end_points[1].cycles_since_end_of_horizontal_retrace, 1);
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enable("lineLine", line.line, 1);
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shader.set_uniform("lineHeight", 1.0f / float(expected_vertical_lines));
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shader.set_uniform("positionScale", float(scale_x), float(scale_y));
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shader.set_uniform("sourceSize", float(source_width), float(source_height));
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shader.set_uniform("source", GLint(source_texture_unit - GL_TEXTURE0));
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return shader;
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}
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