#include <cassert>
#include <cstdlib>
#include <vector>
#include <boost/timer.hpp>
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
int main()
{
const int screen_width = 320;
const int screen_height = 200;
//Initialization
if( SDL_Init( SDL_INIT_VIDEO) < 0 )
{
assert(!"Assume SDL initialization does not fail");
}
//Perform SDL_Quit at program exit
std::atexit(SDL_Quit);
const int bits_per_pixel = 32;
if( !SDL_SetVideoMode( screen_width, screen_height, bits_per_pixel, SDL_OPENGL ))
{
assert(!"Assume SDL video mode setting does not fail");
}
//Initialize OpenGL
glClearColor( 0, 0, 0, 0 );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( 0, screen_width, screen_height, 0, -1, 1 );
glMatrixMode( GL_MODELVIEW );
glDisable(GL_DEPTH_TEST); //In 2D there is no need for a depth test
glLoadIdentity();
if( glGetError() != GL_NO_ERROR )
{
assert(!"Assume OpenGL initialization does not fail");
}
//Set up sprite
const int sprite_width = 10;
const int sprite_height = 10;
int sprite_x = (screen_width / 2) - (sprite_width / 2);
int sprite_y = (screen_height / 2) - (sprite_height / 2);
int sprite_dx = 1;
int sprite_dy = 1;
const int frames_per_second = 60;
const int ticks_per_second = 1000 / frames_per_second;
while(1)
{
//Use timer to keep frame rate constant
boost::timer timer;
//Handle events
SDL_Event event;
SDL_PollEvent( &event );
if( event.type == SDL_QUIT ) break;
//Move the square
sprite_x+=sprite_dx;
sprite_y+=sprite_dy;
//Make the square bounce
if (sprite_x < 0 || sprite_x + sprite_width > screen_width ) sprite_dx = -sprite_dx;
if (sprite_y < 0 || sprite_y + sprite_height > screen_height ) sprite_dy = -sprite_dy;
//Clear the screen
glClear( GL_COLOR_BUFFER_BIT );
//Start showing the sprite
glTranslatef( sprite_x, sprite_y, 0 );
//Start drawing square
glBegin( GL_QUADS );
glColor4f( 1.0, 1.0, 1.0, 1.0 );
glVertex3f( 0, 0, 0 );
glVertex3f( sprite_width, 0, 0 );
glVertex3f( sprite_width, sprite_height, 0 );
glVertex3f( 0, sprite_height, 0 );
glEnd();
//Reset
glLoadIdentity();
//Update screen
SDL_GL_SwapBuffers();
//Keep frame rate constant
const int ticks_elapsed = static_cast<int>(timer.elapsed() * 1000.0);
if (timer.elapsed() < ticks_per_second)
{
SDL_Delay( ticks_per_second - ticks_elapsed );
}
}
}
|
