MapLibreParticleLab/src/mbgl/programs/line_program.hpp

#pragma once

#include <mbgl/programs/program.hpp>
#include <mbgl/programs/attributes.hpp>
#include <mbgl/programs/uniforms.hpp>
#include <mbgl/programs/textures.hpp>
#include <mbgl/util/geometry.hpp>
#include <mbgl/renderer/layers/render_line_layer.hpp>
#include <mbgl/renderer/cross_faded_property_evaluator.hpp>
#include <cmath>

namespace mbgl {

class RenderTile;
class TransformState;
class LinePatternPos;
class ImagePosition;

namespace uniforms {
MBGL_DEFINE_UNIFORM_SCALAR(float, ratio);
MBGL_DEFINE_UNIFORM_SCALAR(float, tex_y_a);
MBGL_DEFINE_UNIFORM_SCALAR(float, tex_y_b);
MBGL_DEFINE_UNIFORM_SCALAR(float, sdfgamma);
MBGL_DEFINE_UNIFORM_VECTOR(float, 2, patternscale_a);
MBGL_DEFINE_UNIFORM_VECTOR(float, 2, patternscale_b);
MBGL_DEFINE_UNIFORM_VECTOR(float, 2, units_to_pixels);
} // namespace uniforms

using LineLayoutAttributes = TypeList<attributes::pos_normal, attributes::data<uint8_t, 4>>;

class LineProgram final
    : public Program<
          LineProgram,
          shaders::BuiltIn::LineProgram,
          gfx::PrimitiveType::Triangle,
          LineLayoutAttributes,
          TypeList<uniforms::matrix, uniforms::ratio, uniforms::units_to_pixels, uniforms::device_pixel_ratio>,
          TypeList<>,
          style::LinePaintProperties> {
public:
    static constexpr std::string_view Name{"LineProgram"};
    const std::string_view typeName() const noexcept override { return Name; }

    using Program::Program;

    /*
     * @param p vertex position
     * @param e extrude normal
     * @param round whether the vertex uses a round line cap
     * @param up whether the line normal points up or down
     * @param dir direction of the line cap (-1/0/1)
     */
    static LayoutVertex layoutVertex(
        Point<int16_t> p, Point<double> e, bool round, bool up, int8_t dir, int32_t linesofar = 0) {
        return LayoutVertex{
            {{static_cast<int16_t>((p.x * 2) | (round ? 1 : 0)), static_cast<int16_t>((p.y * 2) | (up ? 1 : 0))}},
            {{// add 128 to store a byte in an unsigned byte
              static_cast<uint8_t>(::round(extrudeScale * e.x) + 128),
              static_cast<uint8_t>(::round(extrudeScale * e.y) + 128),

              // Encode the -1/0/1 direction value into the first two bits of .z
              // of a_data. Combine it with the lower 6 bits of `linesofar`
              // (shifted by 2 bites to make room for the direction value). The
              // upper 8 bits of `linesofar` are placed in the `w` component.
              // `linesofar` is scaled down by `LINE_DISTANCE_SCALE` so that we
              // can store longer distances while sacrificing precision.

              // Encode the -1/0/1 direction value into .zw coordinates of
              // a_data, which is normally covered by linesofar, so we need to
              // merge them. The z component's first bit, as well as the sign
              // bit is reserved for the direction, so we need to shift the
              // linesofar.
              static_cast<uint8_t>(((dir == 0 ? 0 : (dir < 0 ? -1 : 1)) + 1) | ((linesofar & 0x3F) << 2)),
              static_cast<uint8_t>(linesofar >> 6)}}};
    }

    /*
     * Scale the extrusion vector so that the normal length is this value.
     * Contains the "texture" normals (-1..1). This is distinct from the extrude
     * normals for line joins, because the x-value remains 0 for the texture
     * normal array, while the extrude normal actually moves the vertex to
     * create the acute/bevelled line join.
     */
    static const int8_t extrudeScale = 63;

    static LayoutUniformValues layoutUniformValues(const style::LinePaintProperties::PossiblyEvaluated&,
                                                   const RenderTile&,
                                                   const TransformState&,
                                                   const std::array<float, 2>& pixelsToGLUnits,
                                                   float pixelRatio);
};

class LinePatternProgram final : public Program<LinePatternProgram,
                                                shaders::BuiltIn::LinePatternProgram,
                                                gfx::PrimitiveType::Triangle,
                                                LineLayoutAttributes,
                                                TypeList<uniforms::matrix,
                                                         uniforms::ratio,
                                                         uniforms::units_to_pixels,
                                                         uniforms::device_pixel_ratio,
                                                         uniforms::scale,
                                                         uniforms::texsize,
                                                         uniforms::fade>,
                                                TypeList<textures::image>,
                                                style::LinePaintProperties> {
public:
    static constexpr std::string_view Name{"LinePatternProgram"};
    const std::string_view typeName() const noexcept override { return Name; }

    using Program::Program;

    static LayoutUniformValues layoutUniformValues(const style::LinePaintProperties::PossiblyEvaluated&,
                                                   const RenderTile&,
                                                   const TransformState&,
                                                   const std::array<float, 2>& pixelsToGLUnits,
                                                   float pixelRatio,
                                                   Size atlasSize,
                                                   const CrossfadeParameters& crossfade);
};

class LineSDFProgram final : public Program<LineSDFProgram,
                                            shaders::BuiltIn::LineSDFProgram,
                                            gfx::PrimitiveType::Triangle,
                                            LineLayoutAttributes,
                                            TypeList<uniforms::matrix,
                                                     uniforms::ratio,
                                                     uniforms::units_to_pixels,
                                                     uniforms::device_pixel_ratio,
                                                     uniforms::patternscale_a,
                                                     uniforms::patternscale_b,
                                                     uniforms::tex_y_a,
                                                     uniforms::tex_y_b,
                                                     uniforms::mix,
                                                     uniforms::sdfgamma>,
                                            TypeList<textures::image>,
                                            style::LinePaintProperties> {
public:
    static constexpr std::string_view Name{"LineSDFProgram"};
    const std::string_view typeName() const noexcept override { return Name; }

    using Program::Program;

    static LayoutUniformValues layoutUniformValues(const style::LinePaintProperties::PossiblyEvaluated&,
                                                   float pixelRatio,
                                                   const RenderTile&,
                                                   const TransformState&,
                                                   const std::array<float, 2>& pixelsToGLUnits,
                                                   const LinePatternPos& posA,
                                                   const LinePatternPos& posB,
                                                   const CrossfadeParameters& crossfade,
                                                   float atlasWidth);
};

class LineGradientProgram final
    : public Program<
          LineGradientProgram,
          shaders::BuiltIn::LineGradientProgram,
          gfx::PrimitiveType::Triangle,
          LineLayoutAttributes,
          TypeList<uniforms::matrix, uniforms::ratio, uniforms::units_to_pixels, uniforms::device_pixel_ratio>,
          TypeList<textures::image>,
          style::LinePaintProperties> {
public:
    static constexpr std::string_view Name{"LineGradientProgram"};
    const std::string_view typeName() const noexcept override { return Name; }

    using Program::Program;

    static LayoutUniformValues layoutUniformValues(const style::LinePaintProperties::PossiblyEvaluated&,
                                                   const RenderTile&,
                                                   const TransformState&,
                                                   const std::array<float, 2>& pixelsToGLUnits,
                                                   float pixelRatio);
};

using LineLayoutVertex = LineProgram::LayoutVertex;
using LineAttributes = LineProgram::AttributeList;

} // namespace mbgl