cpp/openttd-patchpack/source Files · src/video/sdl2_opengl_v.h

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r25014:e1f1bf3a062e 2.1 KiB text/x-c Show Annotation Show as Raw Download as Raw

Patric Stout

Add: [Video] move GameLoop into its own thread

This allows drawing to happen while the GameLoop is doing an
iteration too.

Sadly, not much drawing currently can be done while the GameLoop
is running, as for example PollEvent() or UpdateWindows() can
influence the game-state. As such, they first need to acquire a
lock on the game-state before they can be called.

Currently, the main advantage is the time spend in Paint(), which
for non-OpenGL drivers can be a few milliseconds. For OpenGL this
is more like 0.05 milliseconds; in these instances this change
doesn't add any benefits for now.

This is an alternative to the former "draw-thread", which moved
the drawing in a thread for some OSes. It has similar performance
gain as this does, although this implementation allows for more
finer control over what suffers when the GameLoop takes too
long: drawing or the next GameLoop. For now they both suffer
equally.

/*
 * 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 sdl2_opengl_v.h OpenGL backend of the SDL2 video driver. */

#include "sdl2_v.h"

/** The OpenGL video driver for windows. */
class VideoDriver_SDL_OpenGL : public VideoDriver_SDL_Base {
public:
	VideoDriver_SDL_OpenGL() : gl_context(nullptr), anim_buffer(nullptr) {}

	const char *Start(const StringList &param) override;

	void Stop() override;

	bool HasEfficient8Bpp() const override { return true; }

	bool UseSystemCursor() override { return true; }

	void ClearSystemSprites() override;

	void PopulateSystemSprites() override;

	bool HasAnimBuffer() override { return true; }
	uint8 *GetAnimBuffer() override { return this->anim_buffer; }

	const char *GetName() const override { return "sdl-opengl"; }

protected:
	bool AllocateBackingStore(int w, int h, bool force = false) override;
	void *GetVideoPointer() override;
	void ReleaseVideoPointer() override;
	void Paint() override;
	bool CreateMainWindow(uint w, uint h, uint flags) override;

private:
	void  *gl_context;  ///< OpenGL context.
	uint8 *anim_buffer; ///< Animation buffer from OpenGL back-end.

	const char *AllocateContext();
	void DestroyContext();
};

/** The factory for SDL' OpenGL video driver. */
class FVideoDriver_SDL_OpenGL : public DriverFactoryBase {
public:
	FVideoDriver_SDL_OpenGL() : DriverFactoryBase(Driver::DT_VIDEO, 8, "sdl-opengl", "SDL OpenGL Video Driver") {}
	/* virtual */ Driver *CreateInstance() const override { return new VideoDriver_SDL_OpenGL(); }

protected:
	bool UsesHardwareAcceleration() const override { return true; }
};