other_sdl_opengl

#include "SDL/SDL.h"
#include "SDL/SDL_opengl.h"
#include <math.h>
 
const int SCREEN_WIDTH 	= 640;
const int SCREEN_HEIGHT = 480;
 
//The attributes of the square
const int SQUARE_SIZE 	= 20;
const int SQUARE_SPEED 	= 100;
 
short int ROT_MOVE = 0; // must we move? [-1; 0; 1]
short int QUIT = 0; //QUIT flag [0; 1]
 
//The square
float
	x = 0, y = 0, 		//The offsets of the square
	xVel = 0, yVel = 0, 	//The velocity of the square
	rVel = 0, rotation = 0; //The rotation of the square
 
/* ------------------------------------------------------------------------- */
struct unit {
	float	x, y,
		rot_vel, rot,
		size,
		speed;
	short int
		move, // must we move? [-1; 0; 1]
		live;
};
 
/* ------------------------------------------------------------------------- */
int init_GL()
{
	glClearColor( 0, 0, 0, 0 ); //Set clear color
 
	//Set projection
	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	glOrtho( 0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1 );
 
	//Initialize modelview matrix
	glMatrixMode( GL_MODELVIEW );
	glLoadIdentity();
 
 
	if ( glGetError() != GL_NO_ERROR ) { //If there was any errors
		return 1;
	}
 
	return 0; //If everything initialized
}
 
/* ------------------------------------------------------------------------- */
int init()
{
	if ( SDL_Init( SDL_INIT_EVERYTHING ) < 0 ) {
		return 1;
	}
 
	//Create Window
	if ( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT,
			32, SDL_OPENGL ) == NULL ) {
		return 2;
	}
 
	if ( init_GL() != 0 ) {
		return 3;
	}
 
	SDL_WM_SetCaption( "OpenGL Test", NULL );
 
	return 0;
}
 
/* ------------------------------------------------------------------------- */
void square_handle_input ( SDL_Event event )
{
	if ( event.type == SDL_KEYDOWN )      //If a key was pressed
		switch ( event.key.keysym.sym )        {
			case SDLK_UP:   yVel -= SQUARE_SPEED; break;
			case SDLK_DOWN: yVel += SQUARE_SPEED; break;
			case SDLK_LEFT: xVel -= SQUARE_SPEED; break;
			case SDLK_RIGHT:xVel += SQUARE_SPEED; break;
 
			case SDLK_w:    ROT_MOVE = 1;         break;
			case SDLK_a:    rVel -= 120;          break;
			case SDLK_s:    ROT_MOVE = -1;        break;
			case SDLK_d:    rVel += 120;          break;
 
			case SDLK_q:    QUIT = 1;             break;
 
			default: break;
		}
	else if ( event.type == SDL_KEYUP )     //If a key was released
		switch ( event.key.keysym.sym ) {
			case SDLK_UP:   yVel += SQUARE_SPEED; break;
			case SDLK_DOWN: yVel -= SQUARE_SPEED; break;
			case SDLK_LEFT: xVel += SQUARE_SPEED; break;
			case SDLK_RIGHT:xVel -= SQUARE_SPEED; break;
 
			case SDLK_w:    ROT_MOVE = 0;         break;
			case SDLK_a:    rVel += 120;          break;
			case SDLK_s:    ROT_MOVE = 0;         break;
			case SDLK_d:    rVel -= 120;          break;
 
			default: break;
		}
}
 
/* ------------------------------------------------------------------------- */
void square_move ( Uint32 d_time )
{
	rotation += rVel * ( d_time / 1000.f );
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
#if 0
	x += xVel * ( d_time / 1000.f );     //Move the square <->
	if ( ( x < 0 ) || ( x + SQUARE_SIZE > SCREEN_WIDTH ) ) //If too far
		x -= xVel* ( d_time / 1000.f ); //Move back
 
	y += yVel * ( d_time / 1000.f ); //Move the square up or down
	if ( ( y < 0 ) || ( y + SQUARE_SIZE > SCREEN_HEIGHT ) ) //If too far
		y -= yVel* ( d_time / 1000.f ); //Move back
#endif
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	x += ( SQUARE_SPEED * sinf(rotation*M_PI/180.0f) )
			* ( d_time / 1000.f )  * ROT_MOVE;
 
	y -= ( SQUARE_SPEED * cosf(rotation*M_PI/180.0f) )
			* ( d_time / 1000.f )  * ROT_MOVE;
}
 
/* ------------------------------------------------------------------------- */
void square_show()
{
	//Move to offset
	glTranslatef( x, y, 0 );
	glRotatef( rotation, 0, 0, 1);
 
	glBegin( GL_QUADS );
	{
		glColor4f( 1.0, 1.0, 1.0, 1.0 ); //Set color to white
 
		glVertex3f( -SQUARE_SIZE, -SQUARE_SIZE, 0 );
		glVertex3f(  SQUARE_SIZE, -SQUARE_SIZE, 0 );
		glVertex3f(  SQUARE_SIZE,  SQUARE_SIZE, 0 );
		glVertex3f( -SQUARE_SIZE,  SQUARE_SIZE, 0 );
	}
	glEnd();
 
	glLoadIdentity(); //Reset
}
 
 
/* ------------------------------------------------------------------------- */
int main ( int argc, char *argv[] )
{
	//Initialize
	if ( init() != 0 )
		return 1;
 
	SDL_Event event; //Event handler
 
	int timer = 0;
	timer = SDL_GetTicks();
	struct unit player;
 
	player.x=0,
	player.y=0,
	player.rot_vel=0,
	player.rot=0,
	player.size=15,
	player.speed=120;
	player.move=0, // must we move? [-1; 0; 1]
	player.live=1; // [0;1]
 
 
	while ( QUIT == 0 ) {
		/* While there are events to handle. */
		while ( SDL_PollEvent(&event) ) {
			square_handle_input(event); //Handle key presses
			if ( event.type == SDL_QUIT )
				QUIT = 1;
		}
		square_move( SDL_GetTicks() - timer );
		timer = SDL_GetTicks();
 
		glClear( GL_COLOR_BUFFER_BIT ); //Clear the screen
 
		square_show();
 
		SDL_GL_SwapBuffers(); //Update screen
	}
 
	SDL_QUIT();
 
	return 0;
}