Sdl_image cannot find my jpg image; Won't load - c++

Question

I am currently using the Code::Blocks IDE, c++, opengl and SDL to make a game- and I have hit a severe block in road, if you will. I am using SDL_image to load these jpg images for the textures, but they just will not load. Currently, I have tried placing them in every folder in the project, even places where it would supposedly make no difference. I have tried running both the debug and release versions from the IDE, by double-clicking the executable, and by running the executable from the command line. They all produce the same error: Could not load image: "the path to my image". I have tried using full paths, I have tried using relative paths, I have tried just about everything. I have tried various image formats, to no success. Other useful information may be: I am using ubuntu 11.04, I am using GIMP to create the images, and this is my code in complete (I'm sure most of it is irrelevant, but I am just putting it all down just-in-case):
#include <GL/gl.h>
#include <GL/glu.h>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <Cg/cg.h>// NEW: Cg Header
#include <Cg/cgGL.h>// NEW: Cg OpenGL Specific Header
#include <iostream>
#include <math.h>
#include <string>
#include "../include/Camera.h"
#define WINDOW_WIDTH 640
#define WINDOW_HEIGHT 480
// Keydown booleans
bool key[321];
Uint8 *keystate;
float fogDensity = 0.02f;
static float fog_color[] = { 0.8f, 0.8f, 0.8f, 1.0f };
// Process pending events
bool events()
{
SDL_Event event;
if( !SDL_PollEvent(&event) ){
return true;
}
switch( event.type )
{
case SDL_KEYDOWN : key[ event.key.keysym.sym ]=true; break;
case SDL_KEYUP : key[ event.key.keysym.sym ]=false; break;
case SDL_QUIT : return false; break; //one-per-keypress
}
keystate = SDL_GetKeyState(NULL); //continuous
return true;
}
// Initialze OpenGL perspective matrix
void setup(int width, int height)
{
glViewport( 0, 0, width, height );
glMatrixMode( GL_PROJECTION );
glEnable( GL_DEPTH_TEST );
gluPerspective( 45, (float)width/height, 0.1, 100 );
glMatrixMode( GL_MODELVIEW );
}
Camera* cam = new Camera();
GLuint rocktexture; // This is a handle to our texture object
GLuint earthtexture;
//add some default materials here
const GLfloat light_ambient[] = { 0.0f, 0.0f, 0.0f, 1.0f };
const GLfloat light_diffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_position[] = { 0.0f, 1.0f, 0.0f, 0.0f };
const GLfloat mat_ambient[] = { 0.7f, 0.7f, 0.7f, 1.0f };
const GLfloat mat_diffuse[] = { 0.8f, 0.8f, 0.8f, 1.0f };
const GLfloat mat_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat high_shininess[] = { 100.0f };
void MouseUpdate() {
int x, y;
SDL_GetMouseState(&x,&y);
SDL_WarpMouse(WINDOW_WIDTH/2,WINDOW_HEIGHT/2);
cam->yaw+=(x-WINDOW_WIDTH/2)*0.2;
cam->pitch+=(y-WINDOW_HEIGHT/2)*0.2;
if(cam->pitch<-90) {
cam->pitch=-90;
}
if(cam->pitch>90) {
cam->pitch=90;
}
}
static void display(void)
{
while(events())
{
MouseUpdate();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glRotatef(cam->pitch,1.0,0.0,0.0); //rotate our camera on the x-axis (left and right)
glRotatef(cam->yaw,0.0,1.0,0.0); //rotate our camera on the y-axis (up and down)
glTranslated(cam->camx,cam->camy,cam->camz); //translate the screen to the position of our camera
glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glLightf(GL_LIGHT0, GL_QUADRATIC_ATTENUATION, 0);
//glColor4f(1,1,1,0.5);
glPushMatrix();
glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);
//glDisable(GL_CULL_FACE);
glBindTexture(GL_TEXTURE_2D, rocktexture);
glBegin(GL_TRIANGLE_FAN);
glTexCoord2i(0,0);glVertex3f(-32,0,32);
glTexCoord2i(1,0);glVertex3f(32,0,32);
glTexCoord2i(1,1);glVertex3f(32,0,-32);
glTexCoord2i(0,1);glVertex3f(-32,0,-32);
glEnd();
//glEnable(GL_CULL_FACE);
glPopMatrix();
/*glPushMatrix();
GLUquadric* earth = gluNewQuadric();
gluQuadricTexture(earth, true);
gluQuadricDrawStyle(earth, GLU_FILL);
gluQuadricNormals(earth, GLU_SMOOTH);
gluQuadricOrientation(earth, GLU_OUTSIDE);
gluSphere(earth, 1, 16, 16);
gluDeleteQuadric(earth);
glPopMatrix();*/
glFlush();
SDL_GL_SwapBuffers();
if (key[SDLK_ESCAPE] || key[SDLK_q])
{
std::cout<<"Game Ended."<<std::endl;
exit(0);
}
if (keystate[SDLK_w])
{
cam->camx-=sin(cam->yaw*M_PI/180)/4;
cam->camz+=cos(cam->yaw*M_PI/180)/4;
}
if (keystate[SDLK_s])
{
cam->camx+=sin(cam->yaw*M_PI/180)/4;
cam->camz-=cos(cam->yaw*M_PI/180)/4;
}
if (keystate[SDLK_a])
{
cam->camx+=cos(cam->yaw*M_PI/180)/4;
cam->camz+=sin(cam->yaw*M_PI/180)/4;
}
if (keystate[SDLK_d])
{
cam->camx-=cos(cam->yaw*M_PI/180)/4;
cam->camz-=sin(cam->yaw*M_PI/180)/4;
}
}
}
// Load the OpenGL texture
GLuint loadImage(std::string path, GLuint tx,SDL_Surface* sur)
{
GLenum texture_format;
GLint nOfColors;
if ((sur = SDL_LoadBMP(path.c_str())))
{
// Check that the image's width is a power of 2
if ((sur->w & (sur->w - 1)) != 0)
{
printf("warning: image's width is not a power of 2\n");
}
// Also check if the height is a power of 2
if ((sur->h & (sur->h - 1)) != 0)
{
printf("warning: image's height is not a power of 2\n");
}
// get the number of channels in the SDL surface
nOfColors = sur->format->BytesPerPixel;
if (nOfColors == 4) // contains an alpha channel
{
if (sur->format->Rmask == 0x000000ff)
{
texture_format = GL_RGBA;
}
else
{
texture_format = GL_BGRA;
}
}
else if (nOfColors == 3) // no alpha channel
{
if (sur->format->Rmask == 0x000000ff)
{
texture_format = GL_RGB;
}
else
{
texture_format = GL_BGR;
}
}
else
{
printf("warning: the image is not truecolor.. this will probably break\n");
// this error should not go unhandled
}
// Have OpenGL generate a texture object handle for us
glGenTextures( 1, &tx );
// Bind the texture object
glBindTexture( GL_TEXTURE_2D, tx );
// Set the texture's stretching properties
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
// Edit the texture object's image data using the information SDL_Surface gives us
glTexImage2D( GL_TEXTURE_2D, 0, 3, sur->w, sur->h, 0, GL_BGR, GL_UNSIGNED_BYTE, sur->pixels);
//build mip-maps
gluBuild2DMipmaps(tx, 3, sur->w, sur->h, texture_format, GL_UNSIGNED_BYTE, sur->pixels);
}
else
{
printf("SDL could not load image: %s\n", SDL_GetError());
SDL_Quit();
return 1;
}
// Free the SDL_Surface only if it was successfully created
if (sur)
{
SDL_FreeSurface(sur);
}
delete &texture_format;
delete &nOfColors;
return tx;
}
/* Program entry point */
int main(int argc, char *argv[])
{
cam->camz=-5;
cam->camy=-1;
if ( SDL_Init(SDL_INIT_VIDEO) != 0 )
{
std::cout<<"Unable to initialize SDL: %s\n"<<SDL_GetError()<<std::endl;
return 1;
}
const SDL_VideoInfo* info = SDL_GetVideoInfo();
int vidFlags = SDL_OPENGL | SDL_GL_DOUBLEBUFFER;
if (info->hw_available) {vidFlags |= SDL_HWSURFACE;}
else {vidFlags |= SDL_SWSURFACE;}
//int bpp = info->vfmt->BitsPerPixel;
SDL_SetVideoMode(WINDOW_WIDTH, WINDOW_HEIGHT, 32, vidFlags);
SDL_WM_SetCaption( "Treason", NULL);
SDL_WarpMouse(WINDOW_WIDTH/2, WINDOW_HEIGHT/2);
gluLookAt(cam->camx,cam->camy,cam->camz,0,0,0,0,1,0);
glClearColor(0, 0, 0, 0);//background color white
float lmodel_ambient[] = { 0.4f, 0.4f, 0.4f, 1.0f };
float local_view[] = { 0.0f };
glEnable(GL_TEXTURE_2D);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);
glLightModelf(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SEPARATE_SPECULAR_COLOR);
//glEnable(GL_BLEND);
//glBlendFunc(GL_SRC_ALPHA, GL_ONE);
glEnable(GL_DITHER);
//glHint(GL_PHONG_HINT_WIN, GL_NICEST);
glShadeModel(GL_SMOOTH);//GL_PHONG_WIN
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
/* glEnable(GL_FOG);
glHint(GL_FOG_HINT, GL_NICEST);
glEnable(GL_FOG);
glFogi(GL_FOG_MODE, GL_EXP);
glFogf(GL_FOG_DENSITY, fogDensity);
glFogfv(GL_FOG_COLOR, fog_color);*/
// glEnable(GL_STENCIL_TEST);
//glStencilFunc(GL_KEEP, GL_KEEP, GL_INCR);
SDL_Surface *rocktexsur;
rocktexture = loadImage("rock.jpg", rocktexture, rocktexsur);
SDL_Surface *earthtexsur;
earthtexture = loadImage("earth.jpg", earthtexture, earthtexsur);
setup(WINDOW_WIDTH, WINDOW_HEIGHT);
display();
glDeleteTextures(1, &rocktexture);
glDeleteTextures(1, &earthtexture);
return 0;
}
So if you find anything or know any reason why it would return an "SDL could not load image" Error, please respond! I can't continue on my project until this is resolved because it produces a segfault.

Answer 1

SDL by itself can only load BMP images, and it will return an error if you load anything but a BMP in using the function SDL_LoadBMP(). In order to load JPEGs, you need to use the supplemental library SDL_image, which is available at http://www.libsdl.org/projects/SDL_image/ . As JJG answered, the prototype for the function you have to use is:
SDL_Surface *IMG_Load( const char* );
rather than SDL_LoadBMP().

Answer 2

Not an expert on SDL or C++. But I just spent a minute looking over my tiny program I made a while back. I used:
some_image = IMG_Load( "someimage.jpg" );