I've been out of the programming bit for a good while now. I'm trying to get back into it to contribute something to this community and hardware that I love. I'm not an expert coder by any means but I've already hit a snag. It's probably something simple that I'm just overlooking. If one of you more experienced coders could browse over the code I've written below and see if you can spot my problem/s I'd really appreciate it 
.
Basically, what this code does it display the frames per second (which is about 150, seems a little low to me, PC is getting about 1300), the glob_x & y coords and dst.x & y coords and a little sprite that I can move around the screen. Now, everything works perfectly but at random (and I mean random, it happens at a different time/place on the screen each time) the glob_x or y coord will jump from say, 145 to something like 222334456.3322 or something and the corresponding dst variable will jump to something like 10000. Before I put the coords on the screen, the sprite would just disappear. I figured it really wasn't it was just going off the screen, which is the case. My question is why?
Sorry the code snippit is so long but I wanted to include it all in hopes someone could find the problem.
Any help is much appreciated.
.Basically, what this code does it display the frames per second (which is about 150, seems a little low to me, PC is getting about 1300), the glob_x & y coords and dst.x & y coords and a little sprite that I can move around the screen. Now, everything works perfectly but at random (and I mean random, it happens at a different time/place on the screen each time) the glob_x or y coord will jump from say, 145 to something like 222334456.3322 or something and the corresponding dst variable will jump to something like 10000. Before I put the coords on the screen, the sprite would just disappear. I figured it really wasn't it was just going off the screen, which is the case. My question is why?
Sorry the code snippit is so long but I wanted to include it all in hopes someone could find the problem.
Any help is much appreciated.
Code:
/*-----------------------------------------------------------------------------
Include Files
---------------------------------------------------------------------------*/
#include <stdlib.h>
#include <unistd.h>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <SDL/SDL_ttf.h>
/*-----------------------------------------------------------------------------
Defines
---------------------------------------------------------------------------*/
#define SCREEN_WIDTH 320
#define SCREEN_HEIGHT 240
#define SCREEN_BIT_DEPTH 16
/* Defines for the WIZ controls. */
#define WIZ_UP 0
#define WIZ_UP_LEFT 1
#define WIZ_LEFT 2
#define WIZ_DOWN_LEFT 3
#define WIZ_DOWN 4
#define WIZ_DOWN_RIGHT 5
#define WIZ_RIGHT 6
#define WIZ_UP_RIGHT 7
#define WIZ_MENU 8
#define WIZ_SELECT 9
#define WIZ_L 10
#define WIZ_R 11
#define WIZ_A 12
#define WIZ_B 13
#define WIZ_X 14
#define WIZ_Y 15
#define WIZ_VOL_UP 16
#define WIZ_VOL_DOWN 17
/*-----------------------------------------------------------------------------
Type Definitions
---------------------------------------------------------------------------*/
/*-----------------------------------------------------------------------------
Globals
---------------------------------------------------------------------------*/
SDL_Surface* screen = NULL;
SDL_Surface* text = NULL;
SDL_Event event;
SDL_Joystick* joystick;
TTF_Font* default_font = NULL;
FILE* logfile;
Uint8* keys;
Uint32 FPS = 0;
Uint32 frame_count = 0;
Uint32 tick1, tick2;
float time_delta = 0.0f;
SDL_bool show_fps = SDL_TRUE;
/* Temp. */
SDL_Surface* player = NULL;
float glob_x = 50.0f;
float glob_y = 50.0f;
Uint8 velocity = 60;
/* End Temp. */
/*-----------------------------------------------------------------------------
LoadImage()
Loads an image.
---------------------------------------------------------------------------*/
SDL_Surface* LoadImage(char* file_name) {
/* Local variables. */
SDL_Surface* loaded_image = NULL;
SDL_Surface* optimized_image = NULL;
/* Load the image. */
loaded_image = IMG_Load(file_name);
/* Create an optimized image if nothing went wrong in loading the
image. */
if (loaded_image != NULL) {
optimized_image = SDL_DisplayFormat(loaded_image);
Uint32 colorkey = SDL_MapRGB(optimized_image->format, 255, 0, 255);
/* Set all pixels of colorkey color to be transparent. */
SDL_SetColorKey(optimized_image, SDL_SRCCOLORKEY, colorkey);
/* Free the original image. */
SDL_FreeSurface(loaded_image);
}
/* Return the optimized image. */
return optimized_image;
}
/*-----------------------------------------------------------------------------
RenderText()
Renders text to a surface for rendering on the screen.
---------------------------------------------------------------------------*/
SDL_bool RenderText(TTF_Font* font, Uint32 x, Uint32 y, SDL_Surface* src,
SDL_Surface* dst, char* text, SDL_Color color) {
/* Local variables. */
SDL_Rect position;
position.x = x;
position.y = y;
src = TTF_RenderText_Solid(font, text, color);
SDL_BlitSurface(src, NULL, screen, &position);
SDL_FreeSurface(src);
src = NULL;
return SDL_TRUE;
}
/*-----------------------------------------------------------------------------
Initialize()
Set all data for the engine.
---------------------------------------------------------------------------*/
SDL_bool Initialize(void) {
/* Initialize SDL's subsystems - in this case, only video. */
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK) < 0) {
fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
exit(1);
}
/* Register SDL_Quit to be called at exit and make sure things are cleaned
up when we quit. */
atexit(SDL_Quit);
/* Attempt to create a 320x240 window with 32bit pixels. */
screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BIT_DEPTH,
SDL_SWSURFACE | SDL_FULLSCREEN);
/* If screen wasn't set, return error. */
if (screen == NULL) {
fprintf(stderr, "Unable to set 320x240 video: %s\n", SDL_GetError());
exit(1);
}
/* Set the window caption. */
SDL_WM_SetCaption("Frantic", NULL);
/* Initialize SDL_ttf. */
if (TTF_Init() == -1) {
fprintf(stderr, "Could not initialize TTF!\n");
return SDL_FALSE;
}
/* Open the default program font. */
default_font = TTF_OpenFont("04b03.ttf", 8);
if (default_font == NULL) {
fprintf(stderr, "Error loading default font!\n");
return SDL_FALSE;
}
/* Initialize log file. */
logfile = fopen("log.txt", "w");
/* Open joystick control. */
joystick = SDL_JoystickOpen(0);
SDL_JoystickEventState(SDL_IGNORE);
/* Hide the mouse cursor. */
SDL_ShowCursor(SDL_FALSE);
/* Get the keyboard state for user input. */
keys = SDL_GetKeyState(NULL);
/* Seed the random number generator. */
srand(SDL_GetTicks());
/* Get ticks before entering the main loop. */
tick1 = SDL_GetTicks();
/* Temp. */
/* Load the player image. */
player = SDL_LoadBMP("player.bmp");
//player = LoadImage("player.png");
if (player == NULL) {
printf("Error loading player image!\n");
return SDL_FALSE;
}
/* End Temp. */
/* Return success. */
return SDL_TRUE;
}
/*-----------------------------------------------------------------------------
Render()
Renders to the screen.
---------------------------------------------------------------------------*/
void Render(void) {
/* Local variables. */
SDL_Color text_color = {255, 255, 255};
char sbuf[128];
/* Temp. */
SDL_Rect src = {0, 0, 15, 16};
SDL_Rect dst = {0, 0, 15, 16};
/* End Temp. */
/* Lock the screen surface if needed. */
if (SDL_MUSTLOCK(screen)) {
if (SDL_LockSurface(screen) < 0) {
fprintf(stderr, "Could not lock the screen surface!\n");
return;
}
}
/* Draw here. */
/* Clear the screen to black. */
SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 0, 0, 0));
/* Render the player. */
dst.x = glob_x;
dst.y = glob_y;
SDL_BlitSurface(player, &src, screen, &dst);
/* Test blit coords. */
/*fprintf(logfile, "glob_x: %f\t", glob_x);
fprintf(logfile, "dst.x: %d\t", dst.x);
fprintf(logfile, "glob_y: %f\t", glob_y);
fprintf(logfile, "dst.y: %d\r", dst.y);
*/
/* Show FPS. */
if (show_fps == SDL_TRUE) {
sprintf(sbuf, "FPS = %d", FPS);
RenderText(default_font, 0, 0, text, screen, sbuf, text_color);
}
sprintf(sbuf, "glob_x: %f", glob_x);
RenderText(default_font, 0, 8, text, screen, sbuf, text_color);
sprintf(sbuf, "dst.x: %d", dst.x);
RenderText(default_font, 120, 8, text, screen, sbuf, text_color);
sprintf(sbuf, "glob_y: %f", glob_y);
RenderText(default_font, 0, 16, text, screen, sbuf, text_color);
sprintf(sbuf, "dst.y: %d", dst.y);
RenderText(default_font, 120, 16, text, screen, sbuf, text_color);
/* Unlock if needed. */
if (SDL_MUSTLOCK(screen))
SDL_UnlockSurface(screen);
/* Tell SDL to update the whole screen. */
SDL_UpdateRect(screen, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
}
/*-----------------------------------------------------------------------------
CleanUp()
Free memory and prepare to quit.
---------------------------------------------------------------------------*/
void CleanUp(void) {
fclose(logfile);
SDL_ShowCursor(SDL_TRUE);
if (text != NULL)
SDL_FreeSurface(text);
TTF_CloseFont(default_font);
TTF_Quit();
SDL_JoystickClose(joystick);
if (player != NULL)
SDL_FreeSurface(player);
SDL_Quit();
}
/*-----------------------------------------------------------------------------
main()
Program execution begins here.
---------------------------------------------------------------------------*/
int main(int argc, char *argv[]) {
/* Local variables. */
SDL_Event event;
SDL_bool loop = SDL_TRUE;
Uint32 tick_dif = 0;
/* Initialize. */
if (Initialize() != SDL_TRUE) {
fprintf(stderr, "Initialize() failed!\n");
return SDL_FALSE;
}
/* Main loop. */
while (loop) {
/* Get ticks first thing every loop. */
tick2 = SDL_GetTicks();
/* Calculate the time pasted since getting ticks last. */
time_delta = (tick2 - tick1);
/* Very sloppy FPS code I'm sure ;o). */
tick_dif += time_delta;
if (tick_dif > 1000) {
FPS = frame_count;
tick_dif = 0;
frame_count = 0;
}
time_delta = time_delta * 0.001f;
/* This will be the old ticks next loop. */
tick1 = tick2;
/* Render stuff. */
Render();
/* Process user input. */
SDL_JoystickUpdate();
if (SDL_JoystickGetButton(joystick, WIZ_MENU)
&& SDL_JoystickGetButton(joystick, WIZ_SELECT)) {
loop = 0;
}
if (SDL_JoystickGetButton(joystick, WIZ_A)) {
glob_x = 50;
glob_y = 50;
}
if (SDL_JoystickGetButton(joystick, WIZ_UP))
glob_y -= time_delta * velocity;
if (SDL_JoystickGetButton(joystick, WIZ_LEFT))
glob_x -= time_delta * velocity;
if (SDL_JoystickGetButton(joystick, WIZ_DOWN))
glob_y += time_delta * velocity;
if (SDL_JoystickGetButton(joystick, WIZ_RIGHT))
glob_x += time_delta * velocity;
if (SDL_JoystickGetButton(joystick, WIZ_UP_LEFT)) {
glob_y -= time_delta * velocity;
glob_x -= time_delta * velocity;
}
if (SDL_JoystickGetButton(joystick, WIZ_DOWN_LEFT)) {
glob_x -= time_delta * velocity;
glob_y += time_delta * velocity;
}
if (SDL_JoystickGetButton(joystick, WIZ_DOWN_RIGHT)) {
glob_y += time_delta * velocity;
glob_x += time_delta * velocity;
}
if (SDL_JoystickGetButton(joystick, WIZ_UP_RIGHT)) {
glob_x += time_delta * velocity;
glob_y -= time_delta * velocity;
}
/* Event processing. */
while (SDL_PollEvent(&event)) {
switch (event.type) {
/* If a key was pressed. */
case SDL_KEYDOWN:
switch (event.key.keysym.sym) {
case SDLK_ESCAPE:
loop = 0;
break;
case SDLK_F1:
if (show_fps == SDL_TRUE)
show_fps = SDL_FALSE;
else
show_fps = SDL_TRUE;
break;
default:
break;
}
default:
break;
}
}
/* Update the screen. */
if (SDL_Flip(screen) == -1) {
return 1;
}
/* Increment the FPS counter. */
frame_count++;
}
/* Clean up before exiting! */
CleanUp();
/* Return to the GP2X WIZ menu. */
chdir("/usr/gp2x");
execl("/usr/gp2x/gp2xmenu", "/usr/gp2x/gp2xmenu", NULL);
/* Exit program. */
return SDL_TRUE;
}
