/* SPDX-License-Identifier: GPL-2.0-or-later */

#include "BKE_attribute_math.hh"

namespace blender::attribute_math {

ColorGeometryMixer::ColorGeometryMixer(MutableSpan<ColorGeometry4f> output_buffer,
                                       ColorGeometry4f default_color)
    : buffer_(output_buffer),
      default_color_(default_color),
      total_weights_(output_buffer.size(), 0.0f)
{
  buffer_.fill(ColorGeometry4f(0.0f, 0.0f, 0.0f, 0.0f));
}

void ColorGeometryMixer::mix_in(const int64_t index,
                                const ColorGeometry4f &color,
                                const float weight)
{
  BLI_assert(weight >= 0.0f);
  ColorGeometry4f &output_color = buffer_[index];
  output_color.r += color.r * weight;
  output_color.g += color.g * weight;
  output_color.b += color.b * weight;
  output_color.a += color.a * weight;
  total_weights_[index] += weight;
}

void ColorGeometryMixer::finalize()
{
  for (const int64_t i : buffer_.index_range()) {
    const float weight = total_weights_[i];
    ColorGeometry4f &output_color = buffer_[i];
    if (weight > 0.0f) {
      const float weight_inv = 1.0f / weight;
      output_color.r *= weight_inv;
      output_color.g *= weight_inv;
      output_color.b *= weight_inv;
      output_color.a *= weight_inv;
    }
    else {
      output_color = default_color_;
    }
  }
}

}  // namespace blender::attribute_math