//----------------------------------------------------------------------------//
//                                                                            //
// ozz-animation is hosted at http://github.com/guillaumeblanc/ozz-animation  //
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// Copyright (c) Guillaume Blanc                                              //
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//----------------------------------------------------------------------------//

#ifndef OZZ_OZZ_ANIMATION_RUNTIME_BLENDING_JOB_H_
#define OZZ_OZZ_ANIMATION_RUNTIME_BLENDING_JOB_H_

#include "ozz/base/maths/simd_math.h"
#include "ozz/base/span.h"

namespace ozz {

// Forward declaration of math structures.
namespace math {
struct SoaTransform;
}

namespace animation {

// ozz::animation::BlendingJob is in charge of blending (mixing) multiple poses
// (the result of a sampled animation) according to their respective weight,
// into one output pose.
// The number of transforms/joints blended by the job is defined by the number
// of transforms of the bind pose (note that this is a SoA format). This means
// that all buffers must be at least as big as the bind pose buffer.
// Partial animation blending is supported through optional joint weights that
// can be specified with layers joint_weights buffer. Unspecified joint weights
// are considered as a unit weight of 1.f, allowing to mix full and partial
// blend operations in a single pass.
// The job does not owned any buffers (input/output) and will thus not delete
// them during job's destruction.
struct BlendingJob {
  // Default constructor, initializes default values.
  BlendingJob();

  // Validates job parameters.
  // Returns true for a valid job, false otherwise:
  // -if layer range is not valid (can be empty though).
  // -if additive layer range is not valid (can be empty though).
  // -if any layer is not valid.
  // -if output range is not valid.
  // -if any buffer (including layers' content : transform, joint weights...) is
  // smaller than the bind pose buffer.
  // -if the threshold value is less than or equal to 0.f.
  bool Validate() const;

  // Runs job's blending task.
  // The job is validated before any operation is performed, see Validate() for
  // more details.
  // Returns false if *this job is not valid.
  bool Run() const;

  // Defines a layer of blending input data (local space transforms) and
  // parameters (weights).
  struct Layer {
    // Default constructor, initializes default values.
    Layer();

    // Blending weight of this layer. Negative values are considered as 0.
    // Normalization is performed during the blending stage so weight can be in
    // any range, even though range [0:1] is optimal.
    float weight;

    // The range [begin,end[ of input layer posture. This buffer expect to store
    // local space transforms, that are usually outputted from a sampling job.
    // This range must be at least as big as the bind pose buffer, even though
    // only the number of transforms defined by the bind pose buffer will be
    // processed.
    span<const math::SoaTransform> transform;

    // Optional range [begin,end[ of blending weight for each joint in this
    // layer.
    // If both pointers are nullptr (default case) then per joint weight
    // blending is disabled. A valid range is defined as being at least as big
    // as the bind pose buffer, even though only the number of transforms
    // defined by the bind pose buffer will be processed. When a layer doesn't
    // specifies per joint weights, then it is implicitly considered as
    // being 1.f. This default value is a reference value for the normalization
    // process, which implies that the range of values for joint weights should
    // be [0,1]. Negative weight values are considered as 0, but positive ones
    // aren't clamped because they could exceed 1.f if all layers contains valid
    // joint weights.
    span<const math::SimdFloat4> joint_weights;
  };

  // The job blends the bind pose to the output when the accumulated weight of
  // all layers is less than this threshold value.
  // Must be greater than 0.f.
  float threshold;

  // Job input layers, can be empty or nullptr.
  // The range of layers that must be blended.
  span<const Layer> layers;

  // Job input additive layers, can be empty or nullptr.
  // The range of layers that must be added to the output.
  span<const Layer> additive_layers;

  // The skeleton bind pose. The size of this buffer defines the number of
  // transforms to blend. This is the reference because this buffer is defined
  // by the skeleton that all the animations belongs to.
  // It is used when the accumulated weight for a bone on all layers is
  // less than the threshold value, in order to fall back on valid transforms.
  span<const ozz::math::SoaTransform> bind_pose;

  // Job output.
  // The range of output transforms to be filled with blended layer
  // transforms during job execution.
  // Must be at least as big as the bind pose buffer, but only the number of
  // transforms defined by the bind pose buffer size will be processed.
  span<ozz::math::SoaTransform> output;
};
}  // namespace animation
}  // namespace ozz
#endif  // OZZ_OZZ_ANIMATION_RUNTIME_BLENDING_JOB_H_