/*******************************************
Demo Program to Load a Picture and
Use it as a Texture

The texture crawls across the polygon.

Dannelly - October 2006
********************************************/

#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>

#define	ImageWidth 100 
#define	ImageHeight 71
GLubyte *MyImage;
GLfloat spiny = 0.0;
GLfloat spinz = 0.0;
GLuint  texName;
GLfloat cy = 0.0;   // texture crawl amount

/**************************************************************/
void LoadImage()
{
   FILE *infile;

   // open the image file
   infile = fopen("dannellys.raw","r");
   if (infile == NULL)
     {
      perror ("Unable to Open RAW file\n\n");
      exit (1);
     }
 
   // create space for image, then read from file
   MyImage = (GLubyte *) malloc (ImageHeight * ImageWidth * 3);
   fread (MyImage, ImageHeight*ImageWidth*3, 1, infile);
   fclose (infile);
   printf("done reading image file\n");   
}

/**************************************************************/
void init ()
{    
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   LoadImage();
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
   glGenTextures(1, &texName);
   glBindTexture(GL_TEXTURE_2D, texName);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, ImageWidth, ImageHeight, 
                0, GL_RGB, GL_UNSIGNED_BYTE, MyImage);
}
/**************************************************************/

void display()
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glEnable(GL_TEXTURE_2D);
   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
   glBindTexture(GL_TEXTURE_2D, texName);

   glLoadIdentity();
   glRotatef (spiny, 0.0,1.0,0.0);
   glRotatef (spinz, 0.0,0.0,1.0);
   glBegin(GL_POLYGON);
      // 0,0 on texture is upper-left on polygon
      glTexCoord2f(0.0, cy+1.0); glVertex3f(-20.0, -20.0, 0.0);
      glTexCoord2f(0.0, cy+0.0); glVertex3f(-20.0,  20.0, 0.0); 
      glTexCoord2f(1.0, cy+0.0); glVertex3f( 20.0,  20.0, 0.0);
      glTexCoord2f(1.0, cy+1.0); glVertex3f( 20.0, -20.0, 0.0);
   glEnd();
   glFlush();
   glDisable(GL_TEXTURE_2D);
}

/******************************************************************/
void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(-50,50, -50,50, -50,50);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

/******************************************************************/
void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 'q': exit(0);
      case 'c': cy += 0.1;
                glutPostRedisplay();
                break;
      case 'y': spiny += 5.0;
                glutPostRedisplay();
                break;
      case 'Y': spiny -= 5.0;
                glutPostRedisplay();
                break;
      case 'z': spinz += 5.0;
                glutPostRedisplay();
                break;
      case 'Z': spinz -= 5.0;
                glutPostRedisplay();
                break;
      default:  break;
   }
}
/******************************************************************/

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(500, 500);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   init();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0; 
}