genode/repos/gems/include/polygon_gfx/texturize_rgba.h

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/*
* \brief Texturizing function for polygon painting
* \date 2015-06-29
* \author Norman Feske
*/
/*
* Copyright (C) 2015-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__POLYGON_GFX__TEXTURIZE_RGBA_H_
#define _INCLUDE__POLYGON_GFX__TEXTURIZE_RGBA_H_
/* Genode includes */
#include <util/color.h>
#include <os/pixel_rgba.h>
#include <util/geometry.h>
namespace Polygon {
template <typename PT>
static inline void texturize_rgba(Genode::Point<>, Genode::Point<>, PT *,
unsigned char *, unsigned, PT const *,
unsigned char const *, unsigned);
}
/**
* Texturize scanline
*/
template <typename PT>
static inline void Polygon::texturize_rgba(Genode::Point<> start, Genode::Point<> end,
PT *dst, unsigned char *dst_alpha,
unsigned num_values,
PT const *texture_base,
unsigned char const *alpha_base,
unsigned texture_width)
{
/* sanity check */
if (num_values <= 0) return;
/* use 16.16 fixpoint values for the calculation */
int tx_ascent = ((end.x() - start.x())<<16)/(int)num_values,
ty_ascent = ((end.y() - start.y())<<16)/(int)num_values;
/* set start values for color components */
int tx = start.x()<<16,
ty = start.y()<<16;
for ( ; num_values--; dst++, dst_alpha++) {
/* blend pixel from texture with destination point on surface */
unsigned long src_offset = (ty>>16)*texture_width + (tx>>16);
int const a = alpha_base[src_offset];
*dst = texture_base[src_offset];
*dst_alpha += (unsigned char)(((255 - *dst_alpha)*a) >> 8);
/* walk through texture */
tx += tx_ascent;
ty += ty_ascent;
}
}
#endif /* _INCLUDE__POLYGON_GFX__TEXTURIZE_RGBA_H_ */