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Sindhu
12-01-2009, 11:29 PM
Hi,

I am newbie to openGL, i need to place different images on the surface of the cube using "libjpeg" library for placing images. i am using c in ubuntu.

help me please.

waiting for your valuable answer.
Advance Thanks

Ravikishore
12-02-2009, 04:27 AM
I know how to create cube in openGL, but i don't know how to place images on surface of the cube.

The code below will give you the 3D cube :


code :


#include <GL/gl.h>
#include <GL/glut.h>

GLfloat gAngle = 0.0;

void timer(int value)
{
const int desiredFPS=120;
glutTimerFunc(1000/desiredFPS, timer, ++value);
GLfloat dt = 1./desiredFPS;


gAngle += dt*360./8.;

glutPostRedisplay();
}

void display() {

glClear(GL_COLOR_BUFFER_BIT);

glPushMatrix();
glTranslatef(0,0,-100);
glRotatef(gAngle,1.,1.,1.);
glutWireCube(20.);
glPopMatrix();

glutSwapBuffers();
}

void init() {
glClearColor(0.0, 0.0, 0.0, 0.0);

GLdouble Vol = 10*1.8;
GLdouble Left=-Vol;
GLdouble Right=Vol;
GLdouble Bottom=-Vol;
GLdouble Top=Vol;
GLdouble Near=0;
GLdouble Far=2*Vol;

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(Left, Right, Bottom, Top, Near, Far);

GLdouble eyeX=0;
GLdouble eyeY=0;
GLdouble eyeZ=-100+Vol;
GLdouble centerX=0;
GLdouble centerY=0;
GLdouble centerZ=-100;
GLdouble upX=0;
GLdouble upY=1;
GLdouble upZ=0;

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(eyeX,eyeY,eyeZ,
centerX,centerY,centerZ,
upX,upY,upZ);
}

void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
default:
break;
}
}

int main(int argc, char** argv) {
glutInit(&amp;argc, argv);
glutInitDisplayMode(GLUT_DOUBLE);
glutCreateWindow("FPS test /w glutTimerFunc");

glutTimerFunc(0,timer,0);
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);

init();

glutMainLoop();
return 0;
}

Sindhu
12-02-2009, 11:55 PM
Hi Thank You,

I need to place different images on the sides of the cube using libjpeg library.

I have code for both cube and decompression of the JPEG images, but i don't know how to place jpeg images on the cube.
please give some snippet of code it will help me a lot.

waiting for reply.

Thanking You.

mark ds
12-03-2009, 07:42 AM
Hi. Go to http://nehe.gamedev.net/ - there are many gl tutorial there

Sindhu
12-06-2009, 11:27 PM
Hi Thank you very much.

As i am newbie to openGL, i dint get the correct information about placing different images on the sides of the cube using libjpeg library from above website. please please guide me.

It will help me a lot.

Sindhu
12-09-2009, 10:50 PM
Hi,

My question is what is the function of below code. please explain it How it is functioning.

code :

int load_texture (const char * filename,
unsigned char * dest,
const int format,
const unsigned int size)
{
FILE *fd;
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
unsigned char * line;

cinfo.err = jpeg_std_error (&amp;jerr);
jpeg_create_decompress (&amp;cinfo);

if (0 == (fd = fopen(filename, "rb")))
return 1;

jpeg_stdio_src (&amp;cinfo, fd);
jpeg_read_header (&amp;cinfo, TRUE);
if ((cinfo.image_width != size) || (cinfo.image_height != size))
return 1;

if (GL_RGB == format)
{
if (cinfo.out_color_space == JCS_GRAYSCALE)
return 1;
}
else
if (cinfo.out_color_space != JCS_GRAYSCALE)
return 1;

jpeg_start_decompress (&amp;cinfo);

while (cinfo.output_scanline < cinfo.output_height)
{
line = dest +
(GL_RGB == format ? 3 * size : size) * cinfo.output_scanline;
jpeg_read_scanlines (&amp;cinfo, &amp;line, 1);
}
jpeg_finish_decompress (&amp;cinfo);
jpeg_destroy_decompress (&amp;cinfo);
return 0;
}

please help me from this.. Advance Thanks.

Benoit
12-10-2009, 01:10 AM
Hi,

This code is going to fill a destination buffer (unsigned char* dest argument) from a JPEG file (const char* filename argument).

After calling this function with your JPEG file and a correct buffer as destination, you should use texture mapping OpenGL functions as explained in http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=06.

Best,

Sindhu
12-17-2009, 06:26 AM
Hi,
As i am new to openGL.


How to scale the size of an image ?

please tell me.