C++ C++;帧率脉冲
最近我一直在开发一些SDL包装器供我自己使用,我遇到了一个问题,自从我第一次开始使用SDL库以来一直存在这个问题 看,像其他许多人一样,我一直在使用一个类似于这个的计时器来调节我的帧速率,运动从来都不是平稳的。这看起来不像是双缓冲或vsync问题,而是运动平稳,但周期性地跳跃和口吃(实际上它有一定的脉搏和节奏)。每当帧速率调节被关闭时,脉冲就会消失——当然,一切都变得不可用了),所以我确信这与此有关 我已经组装了一个小应用程序,它只包含计时器和一个围绕它移动的红方块。我将把代码放在这篇文章的末尾。代码是垃圾,不使用任何类型的精灵或任何东西:只要知道无论我对它施加了多少压力(比如,添加更多移动的东西或只是更新屏幕的一部分),它的口吃都是一样的。我尝试了不同的帧速率设置,脉冲总是出现(只是以不同的“节奏”)。不用说,我已经在好几台机器(linux机器,所有机器)上试过了 不管怎样,我一直在阅读,看到其他人有这个问题,但没有真正的答案。一、 首先,我已经了解了delta计时技术,我很乐意尝试,但我这里的问题是这个非常简单的应用程序中的计时器本身。为什么口吃?。这是SDL_GetTicks精度和准确性的问题吗?。我能做些什么来改进它 因此,以下代码适用于那些想尝试它的人:C++ C++;帧率脉冲,c++,sdl,frame-rate,C++,Sdl,Frame Rate,最近我一直在开发一些SDL包装器供我自己使用,我遇到了一个问题,自从我第一次开始使用SDL库以来一直存在这个问题 看,像其他许多人一样,我一直在使用一个类似于这个的计时器来调节我的帧速率,运动从来都不是平稳的。这看起来不像是双缓冲或vsync问题,而是运动平稳,但周期性地跳跃和口吃(实际上它有一定的脉搏和节奏)。每当帧速率调节被关闭时,脉冲就会消失——当然,一切都变得不可用了),所以我确信这与此有关 我已经组装了一个小应用程序,它只包含计时器和一个围绕它移动的红方块。我将把代码放在这篇文章的末尾
#include <SDL/SDL.h>
class fps_control
{
private:
bool apply;
Uint32 ticks_frame_count;
Uint32 ticks_frame_end;
Uint32 ticks_frame_begin;
Uint32 diff;
unsigned int frame_count; //Visible to the outside
unsigned int frame_count_inner; //Keeps count until a second has passed, then overwrites former to give the elapsed frames in a second.
unsigned int frame_length;
unsigned int desired_framerate;
private:
void calculate_frame_length()
{
this->frame_length=1000 / this->desired_framerate;
}
public:
fps_control(unsigned int p_f=30):desired_framerate(p_f), apply(true), ticks_frame_count(0), ticks_frame_end(0), ticks_frame_begin(0), diff(0), frame_count(0), frame_count_inner(0), frame_length(0)
{
this->calculate_frame_length();
}
unsigned int get_frame_count() const {return this->frame_count;}
unsigned int get_desired_framerate() const {return this->desired_framerate;}
void framerate_increase(){this->set_framerate(this->desired_framerate+1);}
void framerate_decrease(){this->set_framerate(this->desired_framerate+1);}
void set_framerate(unsigned int p_param)
{
this->desired_framerate=p_param;
this->calculate_frame_length();
}
void toggle_apply() {this->apply=!this->apply;}
void init()
{
//Call this once before starting, to set the beginning frame count to the initial values.
this->ticks_frame_count=SDL_GetTicks();
this->ticks_frame_begin=this->ticks_frame_count;
this->frame_count_inner=0;
this->frame_count=0;
}
void turn()
{
//Call this when all drawing and logic is done.
if(!this->apply) return; //Only apply when asked for.
//Ask for time before drawing and logic to calculate the difference. Add a frame.
this->ticks_frame_end=SDL_GetTicks();
this->frame_count_inner++;
//Whenever a second has passed, update the visible frame count.
if( (this->ticks_frame_end - this->ticks_frame_count) > 1000)
{
this->frame_count=this->frame_count_inner;
this->frame_count_inner=0;
this->ticks_frame_count=SDL_GetTicks();
}
//Calculate difference and apply delay when needed.
this->diff=this->ticks_frame_end - this->ticks_frame_begin;
if(this->diff < this->frame_length) SDL_Delay(this->frame_length-this->diff);
//Get the beginning time and start again.
this->ticks_frame_begin=SDL_GetTicks();
}
};
class Box
{
private:
SDL_Rect position;
int movement_x;
int movement_y;
public:
Box():movement_x(4), movement_y(4)
{
this->position.x=100;
this->position.y=100;
this->position.w=30;
this->position.h=30;
}
SDL_Rect get_position() {return this->position;}
void move_around()
{
//Won't touch the edges, but doesn't really matter.
if(this->position.x<=0 || this->position.x>=800-this->position.w) this->movement_x=-this->movement_x;
if(this->position.y<=0 || this->position.y>=600-this->position.h) this->movement_y=-this->movement_y;
this->position.x+=this->movement_x;
this->position.y+=this->movement_y;
}
};
bool init_sdl(){return SDL_Init( SDL_INIT_VIDEO ) >= 0;}
void quit_sdl(){SDL_Quit();}
void fill_screen(SDL_Surface * screen)
{
SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format,0,0,0));
}
void update_screen(SDL_Surface * screen, Box& box)
{
SDL_Rect b=box.get_position();
SDL_FillRect(screen, &b, SDL_MapRGB(screen->format, 200, 20, 20));
SDL_Flip(screen);
}
int get_input()
{
SDL_Event event;
while(SDL_PollEvent(&event))
{
if(event.type==SDL_QUIT) return 1;
else if(event.type==SDL_KEYDOWN)
{
switch(event.key.keysym.sym)
{
case SDLK_ESCAPE: return 1; break;
case SDLK_SPACE: return 2; break;
case SDLK_UP: return 3; break;
case SDLK_DOWN: return 4; break;
default: break;
}
}
}
return 0;
}
int main(int argc, char **argv)
{
if(!init_sdl())
{
return 1;
}
else
{
//Init things...
// SDL_Surface * screen=SDL_SetVideoMode(800, 600, 16, SDL_DOUBLEBUF | SDL_HWSURFACE); /*SDL_SWSURFACE | SDL_ANYFORMAT);*/
SDL_Surface * screen=SDL_SetVideoMode(800, 600, 16, SDL_SWSURFACE | SDL_ANYFORMAT);
Box box=Box();
fps_control fps=fps_control(60); //Framerate is set to 60.
bool run=true;
int input=0;
SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format,255,0,0));
//Main loop
fps.init();
while(run)
{
input=get_input();
switch(input)
{
case 1: run=false; break;
case 2: fps.toggle_apply(); break;
case 3: fps.framerate_increase(); break;
case 4: fps.framerate_decrease(); break;
default: break;
}
box.move_around();
fill_screen(screen);
update_screen(screen, box);
fps.turn();
}
quit_sdl();
}
}
#包括
类fps_控制
{
私人:
布尔应用;
Uint32滴答声帧计数;
Uint32勾号(帧)结束;;
Uint32信号帧开始;
Uint32差异;
unsigned int frame_count;//外部可见
unsigned int frame_count_inner;//保持计数直到一秒钟过去,然后覆盖前者以在一秒钟内给出经过的帧。
无符号整数帧长度;
无符号整数所需的\u帧率;
私人:
void计算框架长度()
{
此->帧长度=1000/此->所需的帧速率;
}
公众:
fps_控件(无符号整数p_f=30):所需的_帧速率(p_f)、应用(true)、滴答帧计数(0)、滴答帧结束(0)、滴答帧开始(0)、差异(0)、帧计数(0)、帧内计数(0)、帧长(0)
{
此->计算帧长度();
}
无符号int get_frame_count()常量{返回此->frame_count;}
unsigned int get_desired_framerate()常量{返回此->desired_framerate;}
void framerate_increase(){this->set_framerate(this->desired_framerate+1);}
void framerate_decrease(){this->set_framerate(this->desired_framerate+1);}
void set_帧率(无符号int p_参数)
{
此->所需的帧速率=p_参数;
此->计算帧长度();
}
void toggle_apply(){this->apply=!this->apply;}
void init()
{
//在开始之前调用此函数一次,将开始帧计数设置为初始值。
这->勾选帧计数=SDL\u GetTicks();
this->ticks\u frame\u begin=this->ticks\u frame\u count;
此->帧计数内部=0;
此->帧计数=0;
}
无效回合()
{
//完成所有绘图和逻辑后调用此函数。
如果(!this->apply)返回;//仅在请求时应用。
//在绘图和逻辑计算差异之前要求时间。添加一个框架。
此->勾选\u帧\u结束=SDL\u GetTicks();
此->帧\计数\内部++;
//只要经过一秒钟,就更新可见帧数。
如果((此->滴答声\u帧\u结束-此->滴答声\u帧\u计数)>1000)
{
此->帧计数=此->帧计数内部;
此->帧计数内部=0;
这->勾选帧计数=SDL\u GetTicks();
}
//计算差异并在需要时应用延迟。
this->diff=this->ticks\u frame\u end-this->ticks\u frame\u begin;
如果(this->diffframe\u length)SDL\u延迟(this->frame\u length-this->diff);
//获取开始时间并重新开始。
此->勾选\u frame\u begin=SDL\u GetTicks();
}
};
类框
{
私人:
垂直位置;
int-movement_x;
国际运动协会;
公众:
框():移动x(4),移动y(4)
{
此->位置x=100;
该->位置y=100;
该->位置w=30;
该->位置h=30;
}
SDL_Rect get_position(){返回此->位置;}
无效移动_周围()
{
//不会触及边缘,但并不重要。
如果(this->position.xposition.x>=800 this->position.w)this->movement\ux=-this->movement\ux;
如果(this->position.yposition.y>=600 this->position.h)this->movement\u y=-this->movement\u y;
此->位置.x+=此->移动\u x;
此->位置.y+=此->移动\u y;
}
};
bool init_sdl(){return sdl_init(sdl_init_VIDEO)>=0;}
void quit_sdl(){sdl_quit();}
空隙填充筛网(SDL筛网)
{
SDL_FillRect(屏幕,空,SDL_映射RGB(屏幕->格式,0,0,0));
}
无效更新屏幕(SDL曲面*屏幕、方框和方框)
{
SDL_Rect b=box.get_position();
SDL_FillRect(屏幕和b、SDL_映射RGB(屏幕->格式,200、20、20));
SDL_翻转(屏幕);
}
int get_input()
{
SDL_事件;
while(SDL_事件和事件))
{
if(event.type==SDL_QUIT)返回1;
else if(event.type==SDL\u KEYDOWN)
{
开关(event.key.keysym.sym)
{
案例SDLK_逃逸:返回1;中断;
case-SDLK_空间:返回2;中断;
案例SDLK_UP:返回3;中断;
案例SDLK_故障:返回4;中断;
默认:中断;
}
}
}
返回0;
}
int main(int argc,字符**argv)
{
如果(!init_sdl())
{
返回1;
}
其他的
{
//一些事情。。。
//SDL_表面*屏幕=SDL_设置视频模式(800、600、16、SDL_双BUF | SDL_表面);/*SDL_表面| SDL_任意信息
void framerate_decrease(){this->set_framerate(this->desired_framerate+1);}
void set_framerate (unsigned int p_param) {
desired_framerate = p_param;
calculate_frame_length ();
}
void framerate_decrease() {
if (desired_framerate > 1)
set_framerate (desired_framerate - 1);
}
int t;
while (run) {
t = SDL_GetTicks ();
// ...
t = SDL_GetTicks () - t;
}
int t;
while (run) {
t = SDL_GetTicks ();
// ...
t = SDL_GetTicks () - t;
// if the framerate is too high
if (t < 1000 / FPS) {
// compute the difference to have a total frame time of 1000 / FPS
SDL_Delay ((1000 / FPS) - t);
}
}