SDL_Blit problem

SDL Development
1

Howdy again folks!
Alright, I’m making this arcade shooter, and currently I am working on the
HUD (Heads Up Display), and I am having this problem when it comes to
Blitting.

Here is some code for ya.
HUD.H
#ifndef __hud_h
#define __hud_h

#include “main.h”

class HUD {
public:
HUD();
~HUD();

void DRAW(SDL_Surface *screen);
private:
SDL_Surface *energy_bar;
SDL_Surface *health_bar;

SDL_Rect e_bar_rect;
SDL_Rect h_bar_rect;
};

#endif

HUD.CPP
#include “hud.h”

void HUD::DRAW(SDL_Surface *screen) {
SDL_BlitSurface(energy_bar, NULL, screen, &e_bar_rect);
SDL_BlitSurface(health_bar, NULL, screen, &h_bar_rect);
}

HUD::~HUD() {
SDL_FreeSurface(energy_bar);
}

HUD::HUD() {
energy_bar = SDL_LoadBMP(“images/bar_energy.bmp”);
health_bar = SDL_LoadBMP(“images/bar_health.bmp”);

e_bar_rect.x = 0;
e_bar_rect.y = 0;
e_bar_rect.w = 200;
e_bar_rect.h = 20;

h_bar_rect.x = 0;
h_bar_rect.y = 40;
h_bar_rect.w = 200;
h_bar_rect.h = 20;
}

Alright, I get NO errors when it comes to compiling… but when I run it, it
seg faults (And that’s just not nice).
Now… Get this! When I remove all the code for the health bar(health_bar,
h_bar_rect), it blits just fine (only the energy bar).
WHY?

-Bryan Arant

2

— Bryan Arant skrev: > Howdy
again folks!

Alright, I’m making this arcade shooter, and
currently I am working on the
HUD (Heads Up Display), and I am having this problem
when it comes to
Blitting.

void HUD::DRAW(SDL_Surface *screen) {
SDL_BlitSurface(energy_bar, NULL, screen,
&e_bar_rect);
SDL_BlitSurface(health_bar, NULL, screen,
&h_bar_rect);
}

I believe the correct blitting args should be:
SDL_BlitSurface(energy_bar, &e_bar_rect, screen, 0);

I think you mixed up the source rectangle with the
destination rectangle

A quick look at the SDL_BlitSurface prototype in the
sdl_video header should clear things up

/Anders_____________________________________________________
Do You Yahoo!?
se.yahoo.com

3

Some error checking when loading the bitmaps from disk might help? Other
than that (to my eyes), the code looks ok. Also, are you compiling with
the -Wall switch? This could tell you many things you may have missed
(assuming gcc on linux :slight_smile:

Bryan Arant wrote:> Howdy again folks!

Alright, I’m making this arcade shooter, and currently I am working on the
HUD (Heads Up Display), and I am having this problem when it comes to
Blitting.

Here is some code for ya.
HUD.H
#ifndef __hud_h
#define __hud_h

#include “main.h”

class HUD {
public:
HUD();
~HUD();

void DRAW(SDL_Surface *screen);
private:
SDL_Surface *energy_bar;
SDL_Surface *health_bar;

SDL_Rect e_bar_rect;
SDL_Rect h_bar_rect;
};

#endif

HUD.CPP
#include “hud.h”

void HUD::DRAW(SDL_Surface *screen) {
SDL_BlitSurface(energy_bar, NULL, screen, &e_bar_rect);
SDL_BlitSurface(health_bar, NULL, screen, &h_bar_rect);
}

HUD::~HUD() {
SDL_FreeSurface(energy_bar);
}

HUD::HUD() {
energy_bar = SDL_LoadBMP(“images/bar_energy.bmp”);
health_bar = SDL_LoadBMP(“images/bar_health.bmp”);

e_bar_rect.x = 0;
e_bar_rect.y = 0;
e_bar_rect.w = 200;
e_bar_rect.h = 20;

h_bar_rect.x = 0;
h_bar_rect.y = 40;
h_bar_rect.w = 200;
h_bar_rect.h = 20;
}

Alright, I get NO errors when it comes to compiling… but when I run it,
it seg faults (And that’s just not nice).
Now… Get this! When I remove all the code for the health bar(health_bar,
h_bar_rect), it blits just fine (only the energy bar).
WHY?

-Bryan Arant

–

  • Mik Mifflin
4

I thought that SDL_BlitSurface() was

SDL_BlitSurface(src surface, src rect, dest surface, dest rect)…

That’s still not it, If I remove all the code for the health bar, the energy
bar blits just fine.

-Bryan Arant

“Anders Lowgren” wrote in message
news:<mailman.1009664106.24553.sdl at libsdl.org>…> — Bryan Arant skrev: > Howdy

again folks!

Alright, I’m making this arcade shooter, and
currently I am working on the
HUD (Heads Up Display), and I am having this problem
when it comes to
Blitting.

void HUD::DRAW(SDL_Surface *screen) {
SDL_BlitSurface(energy_bar, NULL, screen,
&e_bar_rect);
SDL_BlitSurface(health_bar, NULL, screen,
&h_bar_rect);
}

I believe the correct blitting args should be:
SDL_BlitSurface(energy_bar, &e_bar_rect, screen, 0);

I think you mixed up the source rectangle with the
destination rectangle

A quick look at the SDL_BlitSurface prototype in the
sdl_video header should clear things up

/Anders

Do You Yahoo!?
se.yahoo.com

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