OpenTTD/src/palette.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file palette.cpp Handling of palettes. */

#include "stdafx.h"
#include "blitter/base.hpp"
#include "blitter/factory.hpp"
#include "gfx_type.h"
#include "landscape_type.h"
#include "palette_func.h"
#include "settings_type.h"
#include "thread.h"

#include "table/palettes.h"

#include "safeguards.h"

Palette _cur_palette;

byte _colour_gradient[COLOUR_END][8];

static std::recursive_mutex _palette_mutex; ///< To coordinate access to _cur_palette.

void DoPaletteAnimations();

void GfxInitPalettes()
{
	std::lock_guard<std::recursive_mutex> lock(_palette_mutex);
	memcpy(&_cur_palette, &_palette, sizeof(_cur_palette));
	DoPaletteAnimations();
}

/**
 * Copy the current palette if the palette was updated.
 * Used by video-driver to get a current up-to-date version of the palette,
 * to avoid two threads accessing the same piece of memory (with a good chance
 * one is already updating the palette while the other is drawing based on it).
 * @param local_palette The location to copy the palette to.
 * @param force_copy Whether to ignore if there is an update for the palette.
 * @return True iff a copy was done.
 */
bool CopyPalette(Palette &local_palette, bool force_copy)
{
	std::lock_guard<std::recursive_mutex> lock(_palette_mutex);

	if (!force_copy && _cur_palette.count_dirty == 0) return false;

	local_palette = _cur_palette;
	_cur_palette.count_dirty = 0;

	if (force_copy) {
		local_palette.first_dirty = 0;
		local_palette.count_dirty = 256;
	}

	return true;
}

#define EXTR(p, q) (((uint16_t)(palette_animation_counter * (p)) * (q)) >> 16)
#define EXTR2(p, q) (((uint16_t)(~palette_animation_counter * (p)) * (q)) >> 16)

void DoPaletteAnimations()
{
	std::lock_guard<std::recursive_mutex> lock(_palette_mutex);

	/* Animation counter for the palette animation. */
	static int palette_animation_counter = 0;
	palette_animation_counter += 8;

	Blitter *blitter = BlitterFactory::GetCurrentBlitter();
	const Colour *s;
	const ExtraPaletteValues *ev = &_extra_palette_values;
	Colour old_val[PALETTE_ANIM_SIZE];
	const uint old_tc = palette_animation_counter;
	uint j;

	if (blitter != nullptr && blitter->UsePaletteAnimation() == Blitter::PALETTE_ANIMATION_NONE) {
		palette_animation_counter = 0;
	}

	Colour *palette_pos = &_cur_palette.palette[PALETTE_ANIM_START];  // Points to where animations are taking place on the palette
	/* Makes a copy of the current animation palette in old_val,
	 * so the work on the current palette could be compared, see if there has been any changes */
	memcpy(old_val, palette_pos, sizeof(old_val));

	/* Fizzy Drink bubbles animation */
	s = ev->fizzy_drink;
	j = EXTR2(512, EPV_CYCLES_FIZZY_DRINK);
	for (uint i = 0; i != EPV_CYCLES_FIZZY_DRINK; i++) {
		*palette_pos++ = s[j];
		j++;
		if (j == EPV_CYCLES_FIZZY_DRINK) j = 0;
	}

	/* Oil refinery fire animation */
	s = ev->oil_refinery;
	j = EXTR2(512, EPV_CYCLES_OIL_REFINERY);
	for (uint i = 0; i != EPV_CYCLES_OIL_REFINERY; i++) {
		*palette_pos++ = s[j];
		j++;
		if (j == EPV_CYCLES_OIL_REFINERY) j = 0;
	}

	/* Radio tower blinking */
	{
		byte i = (palette_animation_counter >> 1) & 0x7F;
		byte v;

		if (i < 0x3f) {
			v = 255;
		} else if (i < 0x4A || i >= 0x75) {
			v = 128;
		} else {
			v = 20;
		}
		palette_pos->r = v;
		palette_pos->g = 0;
		palette_pos->b = 0;
		palette_pos++;

		i ^= 0x40;
		if (i < 0x3f) {
			v = 255;
		} else if (i < 0x4A || i >= 0x75) {
			v = 128;
		} else {
			v = 20;
		}
		palette_pos->r = v;
		palette_pos->g = 0;
		palette_pos->b = 0;
		palette_pos++;
	}

	/* Handle lighthouse and stadium animation */
	s = ev->lighthouse;
	j = EXTR(256, EPV_CYCLES_LIGHTHOUSE);
	for (uint i = 0; i != EPV_CYCLES_LIGHTHOUSE; i++) {
		*palette_pos++ = s[j];
		j++;
		if (j == EPV_CYCLES_LIGHTHOUSE) j = 0;
	}

	/* Dark blue water */
	s = (_settings_game.game_creation.landscape == LT_TOYLAND) ? ev->dark_water_toyland : ev->dark_water;
	j = EXTR(320, EPV_CYCLES_DARK_WATER);
	for (uint i = 0; i != EPV_CYCLES_DARK_WATER; i++) {
		*palette_pos++ = s[j];
		j++;
		if (j == EPV_CYCLES_DARK_WATER) j = 0;
	}

	/* Glittery water */
	s = (_settings_game.game_creation.landscape == LT_TOYLAND) ? ev->glitter_water_toyland : ev->glitter_water;
	j = EXTR(128, EPV_CYCLES_GLITTER_WATER);
	for (uint i = 0; i != EPV_CYCLES_GLITTER_WATER / 3; i++) {
		*palette_pos++ = s[j];
		j += 3;
		if (j >= EPV_CYCLES_GLITTER_WATER) j -= EPV_CYCLES_GLITTER_WATER;
	}

	if (blitter != nullptr && blitter->UsePaletteAnimation() == Blitter::PALETTE_ANIMATION_NONE) {
		palette_animation_counter = old_tc;
	} else if (_cur_palette.count_dirty == 0 && memcmp(old_val, &_cur_palette.palette[PALETTE_ANIM_START], sizeof(old_val)) != 0) {
		/* Did we changed anything on the palette? Seems so.  Mark it as dirty */
		_cur_palette.first_dirty = PALETTE_ANIM_START;
		_cur_palette.count_dirty = PALETTE_ANIM_SIZE;
	}
}

/**
 * Determine a contrasty text colour for a coloured background.
 * @param background Background colour.
 * @param threshold Background colour brightness threshold below which the background is considered dark and TC_WHITE is returned, range: 0 - 255, default 128.
 * @return TC_BLACK or TC_WHITE depending on what gives a better contrast.
 */
TextColour GetContrastColour(uint8_t background, uint8_t threshold)
{
	Colour c = _cur_palette.palette[background];
	/* Compute brightness according to http://www.w3.org/TR/AERT#color-contrast.
	 * The following formula computes 1000 * brightness^2, with brightness being in range 0 to 255. */
	uint sq1000_brightness = c.r * c.r * 299 + c.g * c.g * 587 + c.b * c.b * 114;
	/* Compare with threshold brightness which defaults to 128 (50%) */
	return sq1000_brightness < ((uint) threshold) * ((uint) threshold) * 1000 ? TC_WHITE : TC_BLACK;
}