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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 cpu.h Functions related to CPU specific instructions. */

#ifndef CPU_H
#define CPU_H

/**
 * Get the tick counter from the CPU (high precision timing).
 * @return The count.
 */
uint64 ottd_rdtsc();

/**
 * Get the CPUID information from the CPU.
 * @param info The retrieved info. All zeros on architectures without CPUID.
 * @param type The information this instruction should retrieve.
 */
void ottd_cpuid(int info[4], int type);

/**
 * Check whether the current CPU has the given flag.
 * @param type  The type to be passing to cpuid (usually 1).
 * @param index The index in the returned info array.
 * @param bit   The bit index that needs to be set.
 * @return The value of the bit, or false when there is no CPUID or the type is not available.
 */
bool HasCPUIDFlag(uint type, uint index, uint bit);

#endif /* CPU_H */