Sunday, June 12, 2011

Texture map in solid sphere using GLUT(OpenGL)


 This source code is written in C used to draw a solid sphere using OpenGL and you can map texture in it.
Create a project for OpenGL  and copy and paste this code and use your desire imagefile for texture mapping.You can download source code here.

//main.c

#include <GL/gl.h>
#include <GL/glut.h>
#include <windows.h>
#include <stdio.h>
#include <math.h>
GLuint texture;
double angle = 0;
typedef struct
{
    int X;
    int Y;
    int Z;
    double U;
    double V;
}VERTICES;

const double PI = 3.1415926535897;
const int space = 10;
const int VertexCount = (90 / space) * (360 / space) * 4;
VERTICES VERTEX[VertexCount];
GLuint LoadTextureRAW( const char * filename );



void DisplaySphere (double R, GLuint texture)
{

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);


    int b;
    glScalef (0.0125 * R, 0.0125 * R, 0.0125 * R);
    //glRotatef (90, 1, 0, 0);
   glBindTexture (GL_TEXTURE_2D, texture);
    glBegin (GL_TRIANGLE_STRIP);
    for ( b = 0; b <VertexCount; b++)
    {
        glTexCoord2f (VERTEX[b].U, VERTEX[b].V);
        glVertex3f (VERTEX[b].X, VERTEX[b].Y, -VERTEX[b].Z);
    }



for ( b = 0; b <VertexCount; b++)
{

    glTexCoord2f (VERTEX[b].U, -VERTEX[b].V);

    glVertex3f (VERTEX[b].X, VERTEX[b].Y, VERTEX[b].Z);

}

    glEnd();
}
void CreateSphere (double R, double H, double K, double Z) {
    int n;
    double a;
    double b;
    n = 0;
for( b = 0; b <= 90 - space; b+=space){

    for( a = 0; a <= 360 - space; a+=space)
    {
        VERTEX[n].X = R * sin((a) / 180 * PI) * sin((b) / 180 * PI) - H;
        VERTEX[n].Y = R * cos((a) / 180 * PI) * sin((b) / 180 * PI) + K;
        VERTEX[n].Z = R * cos((b) / 180 * PI) - Z;
        VERTEX[n].V = (2 * b) / 360;
        VERTEX[n].U = (a) / 360;

        n++;
        VERTEX[n].X = R * sin((a) / 180 * PI) * sin((b + space) / 180 * PI) - H;
        VERTEX[n].Y = R * cos((a) / 180 * PI) * sin((b + space) / 180 * PI) + K;
        VERTEX[n].Z = R * cos((b + space) / 180 * PI) - Z;
        VERTEX[n].V = (2 * (b + space)) / 360;
        VERTEX[n].U = (a) / 360;
        n++;
        VERTEX[n].X = R * sin((a + space) / 180 * PI) * sin((b) / 180 * PI) - H;
        VERTEX[n].Y = R * cos((a + space) / 180 * PI) * sin((b) / 180 * PI) + K;
        VERTEX[n].Z = R * cos((b) / 180 * PI) - Z;
        VERTEX[n].V = (2 * b) / 360;
        VERTEX[n].U = (a + space) / 360;
        n++;
        VERTEX[n].X = R * sin((a + space) / 180 * PI) * sin((b + space) /180 * PI) - H;
        VERTEX[n].Y = R * cos((a + space) / 180 * PI) * sin((b + space) /180 * PI) + K;
        VERTEX[n].Z = R * cos((b + space) / 180 * PI) - Z;
        VERTEX[n].V = (2 * (b + space)) / 360;
        VERTEX[n].U = (a + space) / 360;
        n++;
    }

}
}
void display (void) {

    glClearDepth(1);
    glClearColor (0.0,0.0,0.0,1.0);
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glTranslatef(0,0,-10);
    glRotatef(angle,0,1,0);
    DisplaySphere(5, texture);
    glutSwapBuffers();
    angle ++;
}
void init (void) {
    glEnable(GL_DEPTH_TEST);
    glEnable( GL_TEXTURE_2D );

    glDepthFunc(GL_LEQUAL);

    texture= LoadTextureRAW( "your_image_name.bmp" );

    CreateSphere(30,0,0,0);
}
void reshape (int w, int h) {

    glViewport (0, 0, (GLsizei)w, (GLsizei)h);

    glMatrixMode (GL_PROJECTION);

    glLoadIdentity ();

    gluPerspective (60, (GLfloat)w / (GLfloat)h, 0.1, 100.0);

    glMatrixMode (GL_MODELVIEW);
}
int main (int argc, char **argv) {

    glutInit (&argc, argv);

    glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH);

    glutInitWindowSize (500, 500);

    glutInitWindowPosition (100, 100);

    glutCreateWindow ("A basic OpenGL Window");

    init();

    glutDisplayFunc (display);

    glutIdleFunc (display);

    glutReshapeFunc (reshape);

    glutMainLoop ();

    return 0;
}
GLuint LoadTextureRAW( const char * filename )
{

  GLuint texture;

  int width, height;

  unsigned char * data;

  FILE * file;



  file = fopen( filename, "rb" );

  if ( file == NULL ) return 0;



  width = 1024;

  height = 512;

  data = (unsigned char *)malloc( width * height * 3 );


    //int size = fseek(file,);
  fread( data, width * height * 3, 1, file );

  fclose( file );

for(int i = 0; i < width * height ; ++i)
{
    int index = i*3;
    unsigned char B,R;
    B = data[index];
    R = data[index+2];
    //B = data[index];
    data[index] = R;
    data[index+2] = B;

}


    glGenTextures( 1, &texture );
    glBindTexture( GL_TEXTURE_2D, texture );
    glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST );


    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_REPEAT );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_REPEAT );
    gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,GL_RGB, GL_UNSIGNED_BYTE, data );
    free( data );

return texture;
}

In this method I have drawn sphere using GL_TRIANGLE_STRIP  and you may fill difficult to understand and you may wondering why I haven't drawn sphere using gluSphere. If we use gluSphere then texture mapping technique will be different but will be easy. I have also posted the Article here where you can find simple and easy method for texturing mapping in sphere with full source code.
Simple method for texture mapping on sphere Using gluSphere and gluQuadricTexture in OpenGL

2 comments:

  1. there were build error sir

    ReplyDelete
  2. how to add image file on texture mapping>?

    ReplyDelete