imagefilters.h

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// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2015 Aaron Suen <warr1024@gmail.com>
 
#pragma once
 
#include "irrlichttypes.h"
#include <rect.h>
#include <SColor.h>
 
namespace video
{
        class IImage;
}
 
/* Fill in RGB values for transparent pixels, to correct for odd colors
 * appearing at borders when blending.  This is because many PNG optimizers
 * like to discard RGB values of transparent pixels, but when blending then
 * with non-transparent neighbors, their RGB values will show up nonetheless.
 *
 * This function modifies the original image in-place.
 *
 * Parameter "threshold" is the alpha level below which pixels are considered
 * transparent. Should be 127 when the texture is used with ALPHA_CHANNEL_REF,
 * 0 when alpha blending is used.
 */
void imageCleanTransparent(video::IImage *src, u32 threshold);
 
/* Returns the gamma-correct average color of the image, with transparent pixels
 * ignored. */
video::SColor imageAverageColor(const video::IImage *img);
 
/* Scale a region of an image into another image, using nearest-neighbor with
 * anti-aliasing; treat pixels as crisp rectangles, but blend them at boundaries
 * to prevent non-integer scaling ratio artifacts.  Note that this may cause
 * some blending at the edges where pixels don't line up perfectly, but this
 * filter is designed to produce the most accurate results for both upscaling
 * and downscaling.
 */
void imageScaleNNAA(video::IImage *src, const core::rect<s32> &srcrect, video::IImage *dest);
 
/* Apply a mask to an image.
 * The two images must have identical dimensions and color formats.
 */
void imageApplyMask(video::IImage *dest, const video::IImage *mask);