SDL2-SDL_PollEvent在Ubuntu / Mac OS X上比Windows慢[关闭]

问题描述 投票：-1回答：1

我使用SDL2用C ++编写了一个Space Invaders模拟器，仅用于创建游戏窗口和播放声音（sdl2_mixer）。在Windows上，模拟器可以60 FPS的速度运行（我可以将该值更改为所需的值，并且可以毫无问题地运行），但是如果我在Ubuntu或Mac OS X上构建该游戏，则该游戏将无法播放（可能是所需FPS的10％）。

对此有解释吗？

  • Ubuntu上的渲染器名称：opengl

  • Windows上的渲染器名称：direct3d

  • Renderer标志在Windows上均在Windows上均为0x0a。

编译：

g++ -std=c++11 main.cpp spaceinvadersmachine.cpp intel8080.cpp -lSDL2 -lSDL2_mixer -I/usr/include/SDL2 -I/usr/include/SDL2_mixer -D_REENTRANT -o spaceinvaders.app

这里有一些代码：

//主循环

while (!quitEmulator)
{
    // Handle events on queue
    while (SDL_PollEvent(&events) == 1)
    {
        switch (events.type)
        {
        case SDL_QUIT:
        {
            // Game's window has been closed
            quitEmulator = true;
            break;
        }
        case SDL_KEYDOWN:
        {
            // Set magnification to 1x
            if (events.key.keysym.sym == SDLK_1)
            {
                machine.magnificationFactor = 1.0;
                machine.magnificationRequest = true;
            }

            // Save game request
            if (events.key.keysym.sym == SDLK_2)
            {
                machine.saveGameRequest = true;
            }

            // Load game request
            if (events.key.keysym.sym == SDLK_3)
            {
                machine.loadGameRequest = true;
            }

            // Set magnification to 4x
            if (events.key.keysym.sym == SDLK_4)
            {
                machine.magnificationFactor = 2.0;
                machine.magnificationRequest = true;
            }

            // Set bases dipswitch request
            if (events.key.keysym.sym == SDLK_7)
            {
                machine.dipBasesRequest = true;
            }

            // Set bonus base dipswitch request
            if (events.key.keysym.sym == SDLK_8)
            {
                machine.dipBonusBaseRequest = true;
            }

            // Set magnification to 9x
            if (events.key.keysym.sym == SDLK_9)
            {
                machine.magnificationFactor = 3.0;
                machine.magnificationRequest = true;
            }

            // Set coin informations dipswitch request
            if (events.key.keysym.sym == SDLK_i)
            {
                machine.dipCoinInfoRequest = true;
            }

            // Game paused
            if (events.key.keysym.sym == SDLK_p)
            {
                gamePaused = !gamePaused;
                if (gamePaused)
                    cout << "INFO: Game paused!\n";
                else
                    cout << "INFO: Game resumed!\n";
            }

            // Reset request
            if (events.key.keysym.sym == SDLK_r)
            {
                machine.resetRequest = true;
            }

            // Change color mode
            if (events.key.keysym.sym == SDLK_c)
            {
                machine.coloredFrame = !machine.coloredFrame;

                if (machine.coloredFrame)
                    cout << "INFO: Color mode set to RGB\n";
                else
                    cout << "INFO: Color mode set to B/W\n";
            }

            break;
        }
        }
    }

    if (!gamePaused)
    {
        // Check keyboard inputs
        SDL_PumpEvents();
        machine.checkKeyboardInput();

        // Set bases dipswitch if requested
        if (machine.dipBasesRequest)
        {
            machine.setBasesDipswitch();
        }

        // Set bonus base dipswitch if requested
        if (machine.dipBonusBaseRequest)
        {
            machine.setBonusBaseDipswitch();
        }

        // Set coin informations dipswitch if requested
        if (machine.dipCoinInfoRequest)
        {
            machine.setCoinInfoDipswitch();
        }

        // Change magnification factor if requested
        if (machine.magnificationRequest)
        {
            machine.setMagnification();
        }

        // Check for interrupt
        if (CPUInterruptDeltaCycles >= cyclePerInterrupt)
        {
            CPUInterruptDeltaCycles = 0;

            machine.interruptRequest = true;

            if (machine.lastInterruptNumber == 1) // RST 1
            {
                machine.interruptNumber = 2; // RST 2
            }
            else // RST 2
            {
                machine.interruptNumber = 1; // RST 1
            }

            machine.lastInterruptNumber = machine.interruptNumber;
        }
        else
        {
            machine.interruptRequest = false;
        }

        // Execute next instruction
        CPU.executeROM(machine.interruptRequest, machine.interruptNumber);

        // Increments CPU's cycle counters
        CPUDeltaCycles += CPU.CPUCycles;
        CPUInterruptDeltaCycles += CPU.CPUCycles;

        // Check if OPCode is known
        if (CPU.unimplementedOPCode)
            quitEmulator = true;

        // Check for I/O
        machine.checkIO();

        // Check if a frame must be drawn
        // Save and Load if requested
        if (CPUDeltaCycles >= cyclePerFrame)
        {
            CPUDeltaCycles = 0;
            machine.createFrame();
            machine.showFrame();
            drewFrames += 1;

            while ((SDL_GetTicks() - lastFPSSynchronization) < frameTimeInterval)
            {
                // Waiting
                ;
            }

            lastFPSSynchronization = SDL_GetTicks();

            if (machine.saveGameRequest)
            {
                machine.saveGameRequest = false;
                machine.saveGame(CPUInterruptDeltaCycles);
            }

            if (machine.loadGameRequest)
            {
                machine.loadGameRequest = false;
                machine.loadGame(CPUInterruptDeltaCycles);

                // Remove pending keyboard events
                SDL_FlushEvent(SDL_KEYDOWN);
                SDL_FlushEvent(SDL_KEYUP);
                SDL_PumpEvents();
            }
        }

        // Reset if requested
        if (machine.resetRequest)
        {
            machine.resetRequest = false;
            machine.resetMachine();
        }
    }
}

编辑

[我试图注释掉创建框架的部分（因此窗口上没有框架更新），并且游戏仍然很慢（音频仍在播放，所以问题不在框架创建功能之内。

编辑n-1

我发现问题出在SDL_PumpEvents和SDL_PollEvent函数。可以消除主循环中的第一个，但显然不能消除第二个。为什么轮询事件太慢？ Windows和Ubuntu上的事件编号都相同]

[SOLUTION]

正如我之前写的那样，问题是SDL_PollEvent函数在Ubuntu上比Windows上慢。这将我的注意力转移到了主循环上，我发现了一个问题：新事件轮询是在主循环的每个循环上而不是每个帧（每秒60次）上进行的，因此这严重降低了执行速度。在Windows上这不是问题，因为有足够的时间每16 ms绘制一帧，但是在Ubuntu上是一个问题，其中SDL_PollEvent较慢并且绘制帧的时间不及时。

所以我移动了轮询处理程序，以便每秒仅检查60次用户输入。 不要将轮询功能放入主while循环内！

这里是新代码：

// NEW MAIN循环

while (!quitEmulator)
{
    if (!gamePaused)
    {
        // Check keyboard inputs
        machine.checkKeyboardInput();

        // Set bases dipswitch if requested
        if (machine.dipBasesRequest)
        {
            machine.setBasesDipswitch();
        }

        // Set bonus base dipswitch if requested
        if (machine.dipBonusBaseRequest)
        {
            machine.setBonusBaseDipswitch();
        }

        // Set coin informations dipswitch if requested
        if (machine.dipCoinInfoRequest)
        {
            machine.setCoinInfoDipswitch();
        }

        // Change magnification factor if requested
        if (machine.magnificationRequest)
        {
            machine.setMagnification();
        }

        // Check for interrupt
        if (CPUInterruptDeltaCycles >= cyclePerInterrupt)
        {
            CPUInterruptDeltaCycles = 0;

            machine.interruptRequest = true;

            if (machine.lastInterruptNumber == 1) // RST 1
            {
                machine.interruptNumber = 2; // RST 2
            }
            else // RST 2
            {
                machine.interruptNumber = 1; // RST 1
            }

            machine.lastInterruptNumber = machine.interruptNumber;
        }
        else
        {
            machine.interruptRequest = false;
        }

        // Execute next instruction
        CPU.executeROM(machine.interruptRequest, machine.interruptNumber);

        // Increments CPU's cycle counters
        CPUDeltaCycles += CPU.CPUCycles;
        CPUInterruptDeltaCycles += CPU.CPUCycles;

        // Check if OPCode is known
        if (CPU.unimplementedOPCode)
            quitEmulator = true;

        // Check for I/O
        machine.checkIO();

        // Check if a frame must be drawn
        // Save and Load if requested
        if (CPUDeltaCycles >= cyclePerFrame)
        {
            CPUDeltaCycles = 0;
            // Handle events on queue
            while (SDL_PollEvent(&events) == 1)
            {
                switch (events.type)
                {
                case SDL_QUIT:
                {
                    // Game's window has been closed
                    quitEmulator = true;
                    break;
                }
                case SDL_KEYDOWN:
                {
                    // Set magnification to 1x
                    if (events.key.keysym.sym == SDLK_1)
                    {
                        machine.magnificationFactor = 1.0;
                        machine.magnificationRequest = true;
                    }

                    // Save game request
                    if (events.key.keysym.sym == SDLK_2)
                    {
                        machine.saveGameRequest = true;
                    }

                    // Load game request
                    if (events.key.keysym.sym == SDLK_3)
                    {
                        machine.loadGameRequest = true;
                    }

                    // Set magnification to 4x
                    if (events.key.keysym.sym == SDLK_4)
                    {
                        machine.magnificationFactor = 2.0;
                        machine.magnificationRequest = true;
                    }

                    // Set bases dipswitch request
                    if (events.key.keysym.sym == SDLK_7)
                    {
                        machine.dipBasesRequest = true;
                    }

                    // Set bonus base dipswitch request
                    if (events.key.keysym.sym == SDLK_8)
                    {
                        machine.dipBonusBaseRequest = true;
                    }

                    // Set magnification to 9x
                    if (events.key.keysym.sym == SDLK_9)
                    {
                        machine.magnificationFactor = 3.0;
                        machine.magnificationRequest = true;
                    }

                    // Set coin informations dipswitch request
                    if (events.key.keysym.sym == SDLK_i)
                    {
                        machine.dipCoinInfoRequest = true;
                    }

                    // Game paused
                    if (events.key.keysym.sym == SDLK_p)
                    {
                        gamePaused = !gamePaused;
                        if (gamePaused)
                            cout << "INFO: Game paused!\n";
                        else
                            cout << "INFO: Game resumed!\n";
                    }

                    // Reset request
                    if (events.key.keysym.sym == SDLK_r)
                    {
                        machine.resetRequest = true;
                    }

                    // Change color mode
                    if (events.key.keysym.sym == SDLK_c)
                    {
                        machine.coloredFrame = !machine.coloredFrame;

                        if (machine.coloredFrame)
                            cout << "INFO: Color mode set to RGB\n";
                        else
                            cout << "INFO: Color mode set to B/W\n";
                    }

                    break;
                }
                }
            }
            machine.createFrame();
            machine.showFrame();
            drewFrames += 1;

            while ((SDL_GetTicks() - lastFPSSynchronization) < frameTimeInterval)
            {
                // Waiting
                ;
            }

            lastFPSSynchronization = SDL_GetTicks();

            if (machine.saveGameRequest)
            {
                machine.saveGameRequest = false;
                machine.saveGame(CPUInterruptDeltaCycles);
            }

            if (machine.loadGameRequest)
            {
                machine.loadGameRequest = false;
                machine.loadGame(CPUInterruptDeltaCycles);

                // Remove pending keyboard events
                SDL_FlushEvent(SDL_KEYDOWN);
                SDL_FlushEvent(SDL_KEYUP);
                SDL_PumpEvents();
            }
        }

        // Reset if requested
        if (machine.resetRequest)
        {
            machine.resetRequest = false;
            machine.resetMachine();
        }
    }
}

我可以用哪种方式使这个问题脱离保持状态？

c++ c++11 sdl-2
1个回答
0
投票

您正在每帧创建一个新的表面和新的纹理。是的，它将会很慢，创建纹理是一个荒谬的缓慢操作。不要经常这样做。

[如果您需要直接写入像素，请一次创建正确大小的纹理（使用SDL_TEXTUREACCESS_STREAMING），然后使用SDL_LockTexture和SDL_UnlockTexture进行更新（请注意：请勿为此使用SDL_UpdateTexture， （如果有的话）实际上并没有比明智地重新创建纹理性能好得多）。我猜想Windows版本“偶然”是快速的，因为您的驱动程序实现会注意到您在做奇怪的事情，而悄悄地忽略了您在告诉它要做的事情，并且做得更快。

当然不用看代码，很难说这是它的[[only问题，但这很可能是一个瓶颈，甚至是瓶颈。

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