src/bones/weight.cpp

#include "rive/bones/weight.hpp"
#include "rive/bones/cubic_weight.hpp"
#include "rive/bones/skinnable.hpp"
#include "rive/container_component.hpp"
#include "rive/shapes/cubic_vertex.hpp"
#include "rive/shapes/vertex.hpp"

using namespace rive;

bool Weight::fitsVertex(const Vertex* vertex) const
{
  return !vertex->is<CubicVertex>() || is<CubicWeight>();
}

StatusCode Weight::onAddedDirty(CoreContext* context)
{
  StatusCode code = Super::onAddedDirty(context);
  if (code != StatusCode::Ok)
  {
    return code;
  }
#ifndef WITH_RIVE_EDITOR
  // Runtime-only path; editor build registers via
  // `editorParentChanged` (dispatcher Pass 4.5).
  if (!parent()->is<Vertex>() || !fitsVertex(parent()->as<Vertex>()))
  {
    return StatusCode::MissingObject;
  }

  parent()->as<Vertex>()->weight(this);
#endif

  return StatusCode::Ok;
}

#ifdef WITH_RIVE_EDITOR
void Weight::bindingChanged()
{
  if (parent() == nullptr || parent()->parent() == nullptr)
  {
    return;
  }
  if (auto skinnable = Skinnable::from(parent()->parent()))
  {
    skinnable->bindingChangedForEditor();
  }
}
#endif

static int encodedWeightValue(unsigned int index, unsigned int data)
{
  return (data >> (index * 8)) & 0xFF;
}

Vec2D Weight::deform(
    Vec2D inPoint,
    unsigned int indices,
    unsigned int weights,
    const Mat2D& world,
    const float* boneTransforms)
{
  float xx = 0, xy = 0, yx = 0, yy = 0, tx = 0, ty = 0;
  for (int i = 0; i < 4; i++)
  {
    int weight = encodedWeightValue(i, weights);
    if (weight == 0)
    {
      continue;
    }

    float normalizedWeight = weight / 255.0f;
    int index = encodedWeightValue(i, indices);
    int startBoneTransformIndex = index * 6;
    xx += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
    xy += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
    yx += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
    yy += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
    tx += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
    ty += boneTransforms[startBoneTransformIndex++] * normalizedWeight;
  }

  return Mat2D(xx, xy, yx, yy, tx, ty) * (world * inPoint);
}