int frames, fps, update;
fps = SDL_GetTicks();
update = SDL_GetTicks();
bool done = false;
while (!done) // the main loop, every loop redraws the scene
{
// input checking and scene drawing
if ((SDL_GetTicks() - update) > 1000)
{
stringstream caption;
caption << frames / ((SDL_GetTicks() - fps) / 1000);
SDL_WM_SetCaption(caption.str().c_str(), NULL);
update = SDL_GetTicks();
}
frames++;
SDL_Delay(10);
}[SDL] FPS is extremely high
Author
When I start the application it has an FPS of 1,000,000,000
It keeps going down every second, and finnaly hangs around 10,000,000-20,000,000!
The only thing I draw is an SDL surface and some input checking, the FPS count works like this:
You are calculating it wrong. Here is how I would do that:
int frames=0, update;float fps;update = SDL_GetTicks();bool done = false;while (!done) // the main loop, every loop redraws the scene{ // input checking and scene drawing if ((SDL_GetTicks() - update) > 1000) { stringstream caption; fps = frames / (SDL_GetTicks()-update) * 1000; caption << fps; SDL_WM_SetCaption(caption.str().c_str(), NULL); update = SDL_GetTicks(); frames = 0; } frames++; SDL_Delay(10);}
And you also should use floats to calculate the fps! Even though fps is a float in fps = frames / (SDL_GetTicks()-update) * 1000; the calculation is not done with floats since frames and the SDL_GetTicks()... are both ints. You have to cast at leat one of them to float.
Try this:
header file:
source file:
I have several subsystems running at different framerates using this class.
header file:
#ifndef class_fps_counter_h#define class_fps_counter_h 1#include <SDL/SDL.h>class fps_counter{private: unsigned int app_ticks;//total ticks so far in this app int frame_cap; //limit FPS to this bool cap_frames; //do we need to? float last_fps; float last_timeslice;public: fps_counter(); void set_cap(int fps); void cap_on(); void cap_off(); void tick(); float get_fps(){return last_fps;}; float get_timeslice(){return last_timeslice;};};#endifsource file:
/* * fps_counter.cpp * worms * * Created by Gavin Burton on 27/11/2007. * Copyright 2007 __MyCompanyName__. All rights reserved. * */#include "fps_counter.h"fps_counter::fps_counter(){ frame_cap = 60; cap_off(); last_fps=0; last_timeslice=1;};void fps_counter::tick(){ float fps; float total_ticks,last_ticks; do{ total_ticks = SDL_GetTicks(); last_ticks = total_ticks - app_ticks; fps = 1000.0 / last_ticks; }while ( fps > 1000 || ((fps > frame_cap) && cap_frames)); app_ticks = total_ticks; last_fps = fps; last_timeslice = 1.0f / fps; //printf("Timer updated, last_fps= %f , last_timeslice=%f\n",last_fps,last_timeslice);};void fps_counter::set_cap(int cap){ frame_cap = cap;};void fps_counter::cap_off(){ cap_frames = false;};void fps_counter::cap_on(){ cap_frames = true;};I have several subsystems running at different framerates using this class.
Use it thusly:
To measure the time between ticks. I have each subsystem use one of these, and accumilate the results of get_timeslice until its time to update, then fire off an event of some kind. (e.g. sprites updating at 15fps, physics running at 60, character animations running at 30, etc.)
I don't know why I called it an FPS counter, but its not really a timer (no callbacks) and its not limited to FPS it also does the timeslice.
#include "fps_counter.h"fps_counter * counter = new fps_counter();while(we_don't_want_to_exit){ counter.tick(); float fps = counter.get_fps(); printf("We know that oop is running at %d fps by measuring time between calls of tick()\n");}To measure the time between ticks. I have each subsystem use one of these, and accumilate the results of get_timeslice until its time to update, then fire off an event of some kind. (e.g. sprites updating at 15fps, physics running at 60, character animations running at 30, etc.)
I don't know why I called it an FPS counter, but its not really a timer (no callbacks) and its not limited to FPS it also does the timeslice.
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