//

// SPDX-License-Identifier: BSD-3-Clause

// Copyright (c) Weta Digital, Ltd and Contributors to the OpenEXR Project.

//

#include "ImfDeepCompositing.h"

#include "ImfNamespace.h"

#include <algorithm>

#include <vector>

OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_ENTER

using std::sort;

using std::vector;

DeepCompositing::DeepCompositing ()

{}

DeepCompositing::~DeepCompositing ()

{}

void

DeepCompositing::composite_pixel (

    float        outputs[],

    const float* inputs[],

    const char*  channel_names[],

    int          num_channels,

    int          num_samples,

    int          sources)

{

    for (int i = 0; i < num_channels; i++)

        outputs[i] = 0.0;

    // no samples? do nothing

    if (num_samples == 0) { return; }

    vector<int> sort_order;

    if (sources > 1)

    {

        sort_order.resize (num_samples);

        for (int i = 0; i < num_samples; i++)

            sort_order[i] = i;

        sort (

            &sort_order[0],

            inputs,

            channel_names,

            num_channels,

            num_samples,

            sources);

    }

    for (int i = 0; i < num_samples; i++)

    {

        int   s     = (sources > 1) ? sort_order[i] : i;

        float alpha = outputs[2];

        if (alpha >= 1.0f) return;

        for (int c = 0; c < num_channels; c++)

        {

            outputs[c] += (1.0f - alpha) * inputs[c][s];

        }

    }

}

struct sort_helper

{

    const float** inputs;

    bool          operator() (int a, int b)

    {

        if (inputs[0][a] < inputs[0][b]) return true;

        if (inputs[0][a] > inputs[0][b]) return false;

        if (inputs[1][a] < inputs[1][b]) return true;

        if (inputs[1][a] > inputs[1][b]) return false;

        return a < b;

    }

    sort_helper (const float** i) : inputs (i) {}

};

void

DeepCompositing::sort (

    int          order[],

    const float* inputs[],

    const char*  channel_names[],

    int          num_channels,

    int          num_samples,

    int          sources)

{

    std::sort (order + 0, order + num_samples, sort_helper (inputs));

}

OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_EXIT