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Patric Stout

Fix #6319: [Win32] don't use clipping; draw whole screen every frame (#8726)

When we clip the region that is only been redrawn, something
weird happens on Windows. When pushing 60 frames per second on a
60Hz monitor, it appears that the clipped region is often shown
of another frame, instead of the current.

Examples of this are:
- pause the game, move your mouse to the left, and at the right
speed it totally disappears.
- fast aircrafts seem to be in several places at once, weirdly
lagging behind.
- in title screen, moving your mouse gives you the idea it is
jumping places, instead of smooth movements.

In the end, if you do nothing, everything is correct, so it is
eventually consistent. Just when we are firing many BitBlt in
a clipped region, the in-between is not.

What goes wrong exactly, I honestly do not know. On every frame
that we push to the DC is a mouse painted, but visually it
sometimes appears like it is not. Recording with external software
shows it really is there.
It is also not our eyes playing tricks on us, as the first example
makes it really clear the mouse pointer really is not painted.

And to be clear, with the mouse this is easiest reproduceable,
as high-speed objects are influences by this most. But this happens
for all movement that redraws small regions.

Either way, not using clipped regions resolves the issue completely,
and there appears to be little to no penalty (I failed to measure
any impact of drawing the full screen). So better have a good game
than fast code, I guess?

/*
 * 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 spritecache.h Functions to cache sprites in memory. */

#ifndef SPRITECACHE_H
#define SPRITECACHE_H

#include "gfx_type.h"

/** Data structure describing a sprite. */
struct Sprite {
	uint16 height; ///< Height of the sprite.
	uint16 width;  ///< Width of the sprite.
	int16 x_offs;  ///< Number of pixels to shift the sprite to the right.
	int16 y_offs;  ///< Number of pixels to shift the sprite downwards.
	byte data[];   ///< Sprite data.
};

extern uint _sprite_cache_size;

typedef void *AllocatorProc(size_t size);

void *GetRawSprite(SpriteID sprite, SpriteType type, AllocatorProc *allocator = nullptr);
bool SpriteExists(SpriteID sprite);

SpriteType GetSpriteType(SpriteID sprite);
uint GetOriginFileSlot(SpriteID sprite);
uint32 GetSpriteLocalID(SpriteID sprite);
uint GetSpriteCountForSlot(uint file_slot, SpriteID begin, SpriteID end);
uint GetMaxSpriteID();


static inline const Sprite *GetSprite(SpriteID sprite, SpriteType type)
{
	assert(type != ST_RECOLOUR);
	return (Sprite*)GetRawSprite(sprite, type);
}

static inline const byte *GetNonSprite(SpriteID sprite, SpriteType type)
{
	assert(type == ST_RECOLOUR);
	return (byte*)GetRawSprite(sprite, type);
}

void GfxInitSpriteMem();
void GfxClearSpriteCache();
void IncreaseSpriteLRU();

void ReadGRFSpriteOffsets(byte container_version);
size_t GetGRFSpriteOffset(uint32 id);
bool LoadNextSprite(int load_index, byte file_index, uint file_sprite_id, byte container_version);
bool SkipSpriteData(byte type, uint16 num);
void DupSprite(SpriteID old_spr, SpriteID new_spr);

#endif /* SPRITECACHE_H */