///////////////////////////////////////////////////////////////////////////

//

// Copyright (c) 2007, Industrial Light & Magic, a division of Lucas

// Digital Ltd. LLC

// 

// All rights reserved.

// 

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

// *       Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

// *       Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

// *       Neither the name of Industrial Light & Magic nor the names of

// its contributors may be used to endorse or promote products derived

// from this software without specific prior written permission. 

// 

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

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///////////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------------

//

//	function blurImage() -- performs a hemispherical blur

//

//-----------------------------------------------------------------------------

#include "blurImage.h"

#include "namespaceAlias.h"

#include <resizeImage.h>

#include <cstring>

#include "Iex.h"

#include <iostream>

#include <algorithm>

#include <string.h>

using namespace IMF;

using namespace std;

using namespace IMATH;

inline int

toInt (float x)

{

    return int (x + 0.5f);

}

inline double

sqr (double x)

{

    return x * x;

}

void

blurImage (EnvmapImage &image1, bool verbose)

{

    //

    // Ideally we would blur the input image directly by convolving

    // it with a 180-degree wide blur kernel.  Unfortunately this

    // is prohibitively expensive when the input image is large.

    // In order to keep running times reasonable, we perform the

    // blur on a small proxy image that will later be re-sampled

    // to the desired output resolution.

    //

    // Here's how it works:

    //

    // * If the input image is in latitude-longitude format,

    //   convert it into a cube-face environment map.

    //

    // * Repeatedly resample the image, each time shrinking

    //   it to no less than half its current size, until the

    //   width of each cube face is MAX_IN_WIDTH pixels.

    // 

    // * Multiply each pixel by a weight that is proportinal

    //   to the solid angle subtended by the pixel as seen

    //   from the center of the environment cube.

    //

    // * Create an output image in cube-face format.

    //   The cube faces of the output image are OUT_WIDTH

    //   pixels wide.

    //

    // * For each pixel of the output image:

    //

    //       Set the output pixel's color to black

    //

    //       Determine the direction, d2, from the center of the

    //       output environment cube to the center of the output

    //	     pixel.

    //   

    //       For each pixel of the input image:

    //

    //           Determine the direction, d1, from the center of

    //           the input environment cube to the center of the

    //           input pixel.

    //    

    //           Multiply the input pixel's color by max (0, d1.dot(d2))

    //           and add the result to the output pixel.

    //

    const int MAX_IN_WIDTH = 40;

    const int OUT_WIDTH = 100;

    if (verbose)

	cout << "blurring map image" << endl;

    EnvmapImage image2;

    EnvmapImage *iptr1 = &image1;

    EnvmapImage *iptr2 = &image2;

    int w = image1.dataWindow().max.x - image1.dataWindow().min.x + 1;

    int h = w * 6;

    if (iptr1->type() == ENVMAP_LATLONG)

    {

	//

	// Convert the input image from latitude-longitude

	// to cube-face format.

	//

	if (verbose)

	    cout << "    converting to cube-face format" << endl;

	w /= 4;

	h = w * 6;

	Box2i dw (V2i (0, 0), V2i (w - 1, h - 1));

	resizeCube (*iptr1, *iptr2, dw, 1, 7);

	swap (iptr1, iptr2);

    }

    while (w > MAX_IN_WIDTH)

    {

	//

	// Shrink the image.

	//

	if (w >= MAX_IN_WIDTH * 2)

	    w /= 2;

	else

	    w = MAX_IN_WIDTH;

	h = w * 6;

	if (verbose)

	{

	    cout << "    resizing cube faces "

		    "to " << w << " by " << w << " pixels" << endl;

	}

	Box2i dw (V2i (0, 0), V2i (w - 1, h - 1));

	resizeCube (*iptr1, *iptr2, dw, 1, 7);

	swap (iptr1, iptr2);

    }

    if (verbose)

	cout << "    computing pixel weights" << endl;

    { 

        //

        // Multiply each pixel by a weight that is proportinal

        // to the solid angle subtended by the pixel.

        //

	Box2i dw = iptr1->dataWindow();

	int sof = CubeMap::sizeOfFace (dw);

	Array2D<Rgba> &pixels = iptr1->pixels();

	double weightTotal = 0;

	for (int f = CUBEFACE_POS_X; f <= CUBEFACE_NEG_Z; ++f)

	{

	    if (verbose)

		cout << "        face " << f << endl;

	    CubeMapFace face = CubeMapFace (f);

	    V3f faceDir (0, 0, 0);

            int ix = 0, iy = 0, iz = 0;

	    switch (face)

	    {

	      case CUBEFACE_POS_X:

		faceDir = V3f (1, 0, 0);

                ix = 0;

                iy = 1;

                iz = 2;

		break;

	      case CUBEFACE_NEG_X:

		faceDir = V3f (-1, 0, 0);

                ix = 0;

                iy = 1;

                iz = 2;

		break;

	      case CUBEFACE_POS_Y:

		faceDir = V3f (0, 1, 0);

                ix = 1;

                iy = 0;

                iz = 2;

		break;

	      case CUBEFACE_NEG_Y:

		faceDir = V3f (0, -1, 0);

                ix = 1;

                iy = 0;

                iz = 2;

		break;

	      case CUBEFACE_POS_Z:

		faceDir = V3f (0, 0, 1);

                ix = 2;

                iy = 0;

                iz = 1;

		break;

	      case CUBEFACE_NEG_Z:

		faceDir = V3f (0, 0, -1);

                ix = 2;

                iy = 0;

                iz = 1;

		break;

	    }

	    for (int y = 0; y < sof; ++y)

	    {

		bool yEdge = (y == 0 || y == sof - 1);

		for (int x = 0; x < sof; ++x)

		{

		    bool xEdge = (x == 0 || x == sof - 1);

		    V2f posInFace (x, y);

		    V3f dir =

			CubeMap::direction (face, dw, posInFace).normalized();

		    V2f pos =

			CubeMap::pixelPosition (face, dw, posInFace);

                    //

                    // The solid angle subtended by pixel (x,y), as seen

                    // from the center of the cube, is proportional to the

                    // square of the distance of the pixel from the center

                    // of the cube and proportional to the dot product of

                    // the viewing direction and the normal of the cube

                    // face that contains the pixel.

                    //

                    double weight =

                        (dir ^ faceDir) *

                        (sqr (dir[iy] / dir[ix]) + sqr (dir[iz] / dir[ix]) + 1);

                    //

                    // Pixels at the edges and corners of the

                    // cube are duplicated; we must adjust the

                    // pixel weights accordingly.

                    //

		    if (xEdge && yEdge)

			weight /= 3;

		    else if (xEdge || yEdge)

			weight /= 2;

		    Rgba &pixel = pixels[toInt (pos.y)][toInt (pos.x)];

		    pixel.r *= weight;

		    pixel.g *= weight;

		    pixel.b *= weight;

		    pixel.a *= weight;

		    weightTotal += weight;

		}

	    }

	}

	//

	// The weighting operation above has made the overall image darker.

	// Apply a correction to recover the image's original brightness.

	//

	int w = dw.max.x - dw.min.x + 1;

	int h = dw.max.y - dw.min.y + 1;

	size_t numPixels = w * h;

	double weight = numPixels / weightTotal;

	Rgba *p = &pixels[0][0];

	Rgba *end = p + numPixels;

	while (p < end)

	{

	    p->r *= weight;

	    p->g *= weight;

	    p->b *= weight;

	    p->a *= weight;

	    ++p;

	}

    } 

    { 

	if (verbose)

	    cout << "    generating blurred image" << endl;

	Box2i dw1 = iptr1->dataWindow();

	int sof1 = CubeMap::sizeOfFace (dw1);

	Box2i dw2 (V2i (0, 0), V2i (OUT_WIDTH - 1, OUT_WIDTH * 6 - 1));

	int sof2 = CubeMap::sizeOfFace (dw2);

	iptr2->resize (ENVMAP_CUBE, dw2);

	iptr2->clear ();

	Array2D<Rgba> &pixels1 = iptr1->pixels();

	Array2D<Rgba> &pixels2 = iptr2->pixels();

	for (int f2 = CUBEFACE_POS_X; f2 <= CUBEFACE_NEG_Z; ++f2)

	{

	    if (verbose)

		cout << "        face " << f2 << endl;

	    CubeMapFace face2 = CubeMapFace (f2);

	    for (int y2 = 0; y2 < sof2; ++y2)

	    {

		for (int x2 = 0; x2 < sof2; ++x2)

		{

		    V2f posInFace2 (x2, y2);

		    V3f dir2 = CubeMap::direction

			(face2, dw2, posInFace2);

		    V2f pos2 = CubeMap::pixelPosition

			(face2, dw2, posInFace2);

		    double weightTotal = 0;

		    double rTotal = 0;

		    double gTotal = 0;

		    double bTotal = 0;

		    double aTotal = 0;

		    Rgba &pixel2 =

			pixels2[toInt (pos2.y)][toInt (pos2.x)];

		    for (int f1 = CUBEFACE_POS_X; f1 <= CUBEFACE_NEG_Z; ++f1)

		    {

			CubeMapFace face1 = CubeMapFace (f1);

			for (int y1 = 0; y1 < sof1; ++y1)

			{

			    for (int x1 = 0; x1 < sof1; ++x1)

			    {

				V2f posInFace1 (x1, y1);

				V3f dir1 = CubeMap::direction

				    (face1, dw1, posInFace1);

				V2f pos1 = CubeMap::pixelPosition

				    (face1, dw1, posInFace1);

				double weight = dir1 ^ dir2;

				if (weight <= 0)

				    continue;

				Rgba &pixel1 =

				    pixels1[toInt (pos1.y)][toInt (pos1.x)];

				weightTotal += weight;

				rTotal += pixel1.r * weight;

				gTotal += pixel1.g * weight;

				bTotal += pixel1.b * weight;

				aTotal += pixel1.a * weight;

			    }

			}

		    }

		    pixel2.r = rTotal / weightTotal;

		    pixel2.g = gTotal / weightTotal;

		    pixel2.b = bTotal / weightTotal;

		    pixel2.a = aTotal / weightTotal;

		}

	    }

	}

	swap (iptr1, iptr2);

    } 

    //

    // Depending on how many times we've re-sampled the image,

    // the result is now either in image1 or in image2.

    // If necessary, copy the result into image1.

    //

    if (iptr1 != &image1)

    {

	if (verbose)

	    cout << "    copying" << endl;

	Box2i dw = iptr1->dataWindow();

	image1.resize (ENVMAP_CUBE, dw);

	int w = dw.max.x - dw.min.x + 1;

	int h = dw.max.y - dw.min.y + 1;

	size_t size = w * h * sizeof (Rgba);

	memcpy (&image1.pixels()[0][0], &iptr1->pixels()[0][0], size);

    }

}