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Drawing over a loaded picture

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I loaded a ppm image and I'm having trouble drawing over this image, I just need to draw square or shapes over it and update coordinates. Here is my code: #include<windows.h> // use as needed for your system #include <stdio.h> #include <stdlib.h> #include<gl/Gl.h> #include<gl/glut.h> int n; int m; int *image; void myInit (void) { glClearColor ( 1.0, 1.0, 1.0 , 1.0); glColor3f ( 1.0f, 0.0f, 0.0f ); glPointSize ( 4.0 ); glMatrixMode ( GL_PROJECTION ); glLoadIdentity ( ); gluOrtho2D ( 0.0, 400.0, 1.0, 400.0 ); } void display(void) { //glClear ( GL_COLOR_BUFFER_BIT ); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glRasterPos2i(0,0);glMatrixMode(GL_MODELVIEW); glDrawPixels(n,m,GL_RGB, GL_UNSIGNED_INT, image); //glFlush ( ); glPushMatrix(); glBegin(GL_QUADS); glNormal3f(0.0, 1.0f, 0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f, -2.5f, 2.5f); glTexCoord2f(1.0f, 0.0f); glVertex3f(2.5f, -2.5f, 2.5f); glTexCoord2f(1.0f, 1.0f); glVertex3f(2.5f, -2.5f, -2.5f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, -2.5f, -2.5f); glEnd(); glPopMatrix(); glutSwapBuffers(); } void myreshape(int h, int w) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode (GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, (GLfloat) n, 0.0, (GLfloat) m); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glViewport(0,0,h,w); } int main(int argc, char**argv) { FILE *fd; int k, nm; char c; char b[70]; float s; char red, green, blue; int x, y; fd = fopen("au.ppm", "r"); if(fd == 0) { exit(0); } fscanf(fd, "%s", b); if((b[0] != 'P') || (b[1] != '6')) { printf("%s is not a PPM file!\n", b); exit(0); } fscanf(fd, "%c", &c); fscanf(fd, "%c", &c); while(c == '#') { fscanf(fd, "%[^\n]", b); printf("%s\n", b); fscanf(fd, "%c", &c); printf("%c", c); } ungetc(c,fd); fscanf(fd, "%d %d %d", &n, &m, &k); printf("%d rows %d colums max value = %d\n", n, m, k); nm = n*m; image = malloc(3*sizeof(GLint)*nm); s = 255./k; for(x = 0; x < m; x++) { for(y = n-1; y >= 0; y--) { fscanf(fd, "%c", &red); fscanf(fd, "%c", &green); fscanf(fd, "%c", &blue); image[3*nm - 3*(x*n +y) -3] = green; image[3*nm - 3*(x*n +y) -2] = blue; image[3*nm - 3*(x*n +y) -1] = red; } } glutInit(&argc, argv); //glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitDisplayMode(GLUT_DOUBLE |GLUT_RGB ); glutInitWindowSize(n,m); glutInitWindowPosition(0,0); glutCreateWindow("image"); glutReshapeFunc(myreshape); glutDisplayFunc(display); glPixelTransferf(GL_RED_SCALE, s); glPixelTransferf(GL_GREEN_SCALE, s); glPixelTransferf(GL_BLUE_SCALE, s); glPixelStorei(GL_UNPACK_SWAP_BYTES, GL_TRUE); glClearColor(1.0, 1.0, 1.0, 1.0); myInit ( ); glutMainLoop ( ); } Can somebody help me with this. The only output I'm getting is the image. Any OpenGL experts? Thank you so much!

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