unity/crnlib/crn_dxt1.h

// File: crn_dxt1.h
// See Copyright Notice and license at the end of inc/crnlib.h
#pragma once
#include "crn_dxt.h"

namespace crnlib {
struct dxt1_solution_coordinates {
  inline dxt1_solution_coordinates()
      : m_low_color(0), m_high_color(0) {}

  inline dxt1_solution_coordinates(uint16 l, uint16 h)
      : m_low_color(l), m_high_color(h) {}

  inline dxt1_solution_coordinates(const color_quad_u8& l, const color_quad_u8& h, bool scaled = true)
      : m_low_color(dxt1_block::pack_color(l, scaled)),
        m_high_color(dxt1_block::pack_color(h, scaled)) {
  }

  inline dxt1_solution_coordinates(vec3F nl, vec3F nh) {
#if CRNLIB_DXT_ALT_ROUNDING
    // Umm, wtf?
    nl.clamp(0.0f, .999f);
    nh.clamp(0.0f, .999f);
    color_quad_u8 l((int)floor(nl[0] * 32.0f), (int)floor(nl[1] * 64.0f), (int)floor(nl[2] * 32.0f), 255);
    color_quad_u8 h((int)floor(nh[0] * 32.0f), (int)floor(nh[1] * 64.0f), (int)floor(nh[2] * 32.0f), 255);
#else
    // Fixes the bins
    color_quad_u8 l((int)floor(.5f + nl[0] * 31.0f), (int)floor(.5f + nl[1] * 63.0f), (int)floor(.5f + nl[2] * 31.0f), 255);
    color_quad_u8 h((int)floor(.5f + nh[0] * 31.0f), (int)floor(.5f + nh[1] * 63.0f), (int)floor(.5f + nh[2] * 31.0f), 255);
#endif

    m_low_color = dxt1_block::pack_color(l, false);
    m_high_color = dxt1_block::pack_color(h, false);
  }

  uint16 m_low_color;
  uint16 m_high_color;

  inline void clear() {
    m_low_color = 0;
    m_high_color = 0;
  }

  inline dxt1_solution_coordinates& canonicalize() {
    if (m_low_color < m_high_color)
      utils::swap(m_low_color, m_high_color);
    return *this;
  }

  inline operator size_t() const { return fast_hash(this, sizeof(*this)); }

  inline bool operator==(const dxt1_solution_coordinates& other) const {
    uint16 l0 = math::minimum(m_low_color, m_high_color);
    uint16 h0 = math::maximum(m_low_color, m_high_color);

    uint16 l1 = math::minimum(other.m_low_color, other.m_high_color);
    uint16 h1 = math::maximum(other.m_low_color, other.m_high_color);

    return (l0 == l1) && (h0 == h1);
  }

  inline bool operator!=(const dxt1_solution_coordinates& other) const {
    return !(*this == other);
  }

  inline bool operator<(const dxt1_solution_coordinates& other) const {
    uint16 l0 = math::minimum(m_low_color, m_high_color);
    uint16 h0 = math::maximum(m_low_color, m_high_color);

    uint16 l1 = math::minimum(other.m_low_color, other.m_high_color);
    uint16 h1 = math::maximum(other.m_low_color, other.m_high_color);

    if (l0 < l1)
      return true;
    else if (l0 == l1) {
      if (h0 < h1)
        return true;
    }

    return false;
  }
};

typedef crnlib::vector<dxt1_solution_coordinates> dxt1_solution_coordinates_vec;

CRNLIB_DEFINE_BITWISE_COPYABLE(dxt1_solution_coordinates);

struct unique_color {
  inline unique_color() {}
  inline unique_color(const color_quad_u8& color, uint weight)
      : m_color(color), m_weight(weight) {}

  color_quad_u8 m_color;
  uint m_weight;

  inline bool operator<(const unique_color& c) const {
    return *reinterpret_cast<const uint32*>(&m_color) < *reinterpret_cast<const uint32*>(&c.m_color);
  }

  inline bool operator==(const unique_color& c) const {
    return *reinterpret_cast<const uint32*>(&m_color) == *reinterpret_cast<const uint32*>(&c.m_color);
  }
};

CRNLIB_DEFINE_BITWISE_COPYABLE(unique_color);

class dxt1_endpoint_optimizer {
 public:
  dxt1_endpoint_optimizer();

  struct params {
    params()
        : m_block_index(0),
          m_pPixels(NULL),
          m_num_pixels(0),
          m_dxt1a_alpha_threshold(128U),
          m_quality(cCRNDXTQualityUber),
          m_pixels_have_alpha(false),
          m_use_alpha_blocks(true),
          m_perceptual(true),
          m_grayscale_sampling(false),
          m_endpoint_caching(true),
          m_use_transparent_indices_for_black(false),
          m_force_alpha_blocks(false) {
    }

    uint m_block_index;

    const color_quad_u8* m_pPixels;
    uint m_num_pixels;
    uint m_dxt1a_alpha_threshold;

    crn_dxt_quality m_quality;

    bool m_pixels_have_alpha;
    bool m_use_alpha_blocks;
    bool m_perceptual;
    bool m_grayscale_sampling;
    bool m_endpoint_caching;
    bool m_use_transparent_indices_for_black;
    bool m_force_alpha_blocks;
  };

  struct results {
    inline results()
        : m_pSelectors(NULL) {}

    uint64 m_error;

    uint16 m_low_color;
    uint16 m_high_color;

    uint8* m_pSelectors;
    bool m_alpha_block;
    bool m_reordered;
    bool m_alternate_rounding;
    bool m_enforce_selector;
    uint8 m_enforced_selector;
  };

  bool compute(const params& p, results& r);

 private:
  const params* m_pParams;
  results* m_pResults;

  bool m_perceptual;
  bool m_evaluate_hc;

  typedef crnlib::vector<unique_color> unique_color_vec;

  //typedef crnlib::hash_map<uint32, uint32, bit_hasher<uint32> > unique_color_hash_map;
  typedef crnlib::hash_map<uint32, uint32> unique_color_hash_map;
  unique_color_hash_map m_unique_color_hash_map;

  unique_color_vec m_unique_colors;  // excludes transparent colors!
  unique_color_vec m_evaluated_colors;
  unique_color_vec m_temp_unique_colors;

  struct {
    uint64 low, high;
  } m_rDist[32], m_gDist[64], m_bDist[32];
  
  uint m_total_unique_color_weight;

  bool m_has_transparent_pixels;

  vec3F_array m_norm_unique_colors;
  vec3F m_mean_norm_color;

  vec3F_array m_norm_unique_colors_weighted;
  vec3F m_mean_norm_color_weighted;

  vec3F m_principle_axis;

  crnlib::vector<uint16> m_unique_packed_colors;
  crnlib::vector<uint8> m_trial_selectors;

  crnlib::vector<vec3F> m_low_coords;
  crnlib::vector<vec3F> m_high_coords;

  enum { cMaxPrevResults = 4 };
  dxt1_solution_coordinates m_prev_results[cMaxPrevResults];
  uint m_num_prev_results;

  crnlib::vector<vec3I> m_lo_cells;
  crnlib::vector<vec3I> m_hi_cells;

  struct potential_solution {
    potential_solution()
        : m_coords(), m_error(cUINT64_MAX), m_alpha_block(false) {
    }

    dxt1_solution_coordinates m_coords;
    crnlib::vector<uint8> m_selectors;
    uint64 m_error;
    bool m_alpha_block;
    bool m_alternate_rounding;
    bool m_enforce_selector;
    uint8 m_enforced_selector;

    void clear() {
      m_coords.clear();
      m_selectors.resize(0);
      m_error = cUINT64_MAX;
      m_alpha_block = false;
    }

    bool are_selectors_all_equal() const {
      if (m_selectors.empty())
        return false;
      const uint s = m_selectors[0];
      for (uint i = 1; i < m_selectors.size(); i++)
        if (m_selectors[i] != s)
          return false;
      return true;
    }
  };

  potential_solution m_trial_solution;
  potential_solution m_best_solution;

  typedef crnlib::hash_map<uint, empty_type> solution_hash_map;
  solution_hash_map m_solutions_tried;

  bool refine_solution(int refinement_level = 0);

  bool evaluate_solution(const dxt1_solution_coordinates& coords, bool alternate_rounding = false);
  bool evaluate_solution_uber(const dxt1_solution_coordinates& coords, bool alternate_rounding);
  bool evaluate_solution_fast(const dxt1_solution_coordinates& coords, bool alternate_rounding);
  bool evaluate_solution_hc_perceptual(const dxt1_solution_coordinates& coords, bool alternate_rounding);
  bool evaluate_solution_hc_uniform(const dxt1_solution_coordinates& coords, bool alternate_rounding);
  void compute_selectors();
  void compute_selectors_hc();

  void find_unique_colors();
  void handle_multicolor_block();
  void compute_pca(vec3F& axis, const vec3F_array& norm_colors, const vec3F& def);
  void compute_vectors(const vec3F& perceptual_weights);
  void return_solution();
  void try_combinatorial_encoding();
  void compute_endpoint_component_errors(uint comp_index, uint64 (&error)[4][256], uint64 (&best_remaining_error)[4]);
  void optimize_endpoint_comps();
  void optimize_endpoints(vec3F& low_color, vec3F& high_color);
  bool try_alpha_as_black_optimization();
  bool try_average_block_as_solid();
  bool try_median4(const vec3F& low_color, const vec3F& high_color);

  void compute_internal(const params& p, results& r);

  unique_color lerp_color(const color_quad_u8& a, const color_quad_u8& b, float f, int rounding = 1);

  inline uint color_distance(bool perceptual, const color_quad_u8& e1, const color_quad_u8& e2, bool alpha);
};

}  // namespace crnlib