chart_shader_presets.hpp

Go to the documentation of this file.

#pragma once
 
// Named chart-shader presets: ready-made `half4 shade(PulpChart g)` sources for
// the bevelled caps, inset tracks, tubes and LED light pipes audio UIs are
// built from. Each preset is ordinary SkSL fed to the existing chart API —
// `Canvas::draw_sdf_shape_with_shader` in C++, `setWidgetShaderChart` or
// `setWidgetShaderChartPreset` from JS — so it works on every charted shape
// (flat arc, ring, flat and rounded segment, stadium) and can be copied and
// edited like hand-written source.
//
// Shading reads the chart's cross-section: `u = cross / halfWidth` runs from
// -1 to +1 across the band, a height profile over `u` gives a surface normal
// along the chart normal (tan.y, -tan.x), and a directional light is applied
// with Lambert diffuse and Blinn-Phong specular. Colours are decoded from sRGB
// to linear before any lighting arithmetic and encoded back afterwards, and a
// flat face facing the viewer reproduces the authored colour exactly.
 
#include <pulp/canvas/canvas.hpp>
 
#include <string>
#include <string_view>
#include <vector>
 
namespace pulp::view {

enum class ChartProfile {
    round,   
    flat,    
    chamfer, 
};

inline constexpr float kChartGlowSigmaMax = 256.0f;
 
struct ChartShaderPresetOptions {
    canvas::Color color = canvas::Color::rgba8(150, 155, 165);
    canvas::Color accent = canvas::Color::rgba8(100, 170, 255);
    float light_angle_deg = 120.0f;
    float light_elevation_deg = 45.0f;
    bool pressed = false;
    ChartProfile profile = ChartProfile::round;
    float bevel_width = 0.35f;
    float intensity = 1.0f;
    float glow_sigma = 6.0f;
};
 
struct ChartShaderPreset {
    std::string sksl;
    float reach = 0.0f;
    std::string error;
};

const std::vector<std::string>& chart_shader_preset_names();

ChartShaderPreset make_chart_shader_preset(std::string_view name,
                                           const ChartShaderPresetOptions& options = {});

float chart_glow_reach(float sigma, float intensity);

bool parse_chart_profile(std::string_view name, ChartProfile& out);
 
} // namespace pulp::view