// Mipmaps are a group of the same image, scaled to different sizes.
// Instead of resizing the texture to fit the object on the fly,
// opengl will pick the mipmap that best fits the shape and textures
// it with that. This fixes dodgy looking textures, and smooths
// out the overall effect. Making a better looking image.

// To do this all we need is this line in our LoadTexture function:
// gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height, GL_RGB, GL_UNSIGNED_BYTE, data ); 
// Instead of the line:
// glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
// The 'data' being the texture, the width and height being the width and height
// of the texture file.

//Then you just bind it like you would a normal texture.

//But because we are now using mipmaps, we also want to change:
//	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
//	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
// To
//	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
//	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR );

//Simply so that we can get better looking textures.

// And wasn't that simple, we now have mipmaps :D
// If you have any questions, please email me at swiftless@gmail.com

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

GLuint texture; //the array for our texture

GLfloat angle = 0.0;

GLuint LoadTexture( const char * filename, int width, int height )
{
	GLuint texture;
	unsigned char * data;
	FILE * file;

	//The following code will read in our RAW file
	file = fopen( filename, "rb" );
	if ( file == NULL ) return 0;
	data = (unsigned char *)malloc( width * height * 3 );
	fread( data, width * height * 3, 1, file );
	fclose( file );

	glGenTextures( 1, &texture ); //generate the texture with the loaded data
	glBindTexture( GL_TEXTURE_2D, texture ); //bind the texture to it's array
	glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ); //set texture environment parameters

	//here we are setting what textures to use and when. The MIN filter is which quality to show
	//when the texture is near the view, and the MAG filter is which quality to show when the texture
	//is far from the view.

	//The qualities are (in order from worst to best)
	//GL_NEAREST
	//GL_LINEAR
	//GL_LINEAR_MIPMAP_NEAREST
	//GL_LINEAR_MIPMAP_LINEAR

	//And if you go and use extensions, you can use Anisotropic filtering textures which are of an
	//even better quality, but this will do for now.
	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR );

	//Here we are setting the parameter to repeat the texture instead of clamping the texture
	//to the edge of our shape. 
	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
	glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );

	//Generate the texture with mipmaps
	gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height, GL_RGB, GL_UNSIGNED_BYTE, data ); 
	free( data ); //free the texture
	return texture; //return whether it was successfull
}

void FreeTexture( GLuint texture )
{
  glDeleteTextures( 1, &texture ); 
}

void square (void) {
	glBindTexture( GL_TEXTURE_2D, texture ); //bind our texture
	glPushMatrix();
	glRotatef( angle, 1.0f, 1.0f, 1.0f );
	glBegin (GL_QUADS);
	glTexCoord2d(0.0,0.0); glVertex2d(-1.0,-1.0);
    glTexCoord2d(1.0,0.0); glVertex2d(+1.0,-1.0);
    glTexCoord2d(1.0,1.0); glVertex2d(+1.0,+1.0);
    glTexCoord2d(0.0,1.0); glVertex2d(-1.0,+1.0);
	glEnd();
	glPopMatrix();
	glPushMatrix();
	glTranslatef( 0,0,-5 );
	glBegin (GL_QUADS);
	glTexCoord2d(0.0,0.0); glVertex2d(-1.0,-1.0);
    glTexCoord2d(1.0,0.0); glVertex2d(+1.0,-1.0);
    glTexCoord2d(1.0,1.0); glVertex2d(+1.0,+1.0);
    glTexCoord2d(0.0,1.0); glVertex2d(-1.0,+1.0);
	glEnd();
	glPopMatrix();
}

void display (void) {
	glClearColor (0.0,0.0,0.0,1.0);
    glClear (GL_COLOR_BUFFER_BIT);
    glLoadIdentity();  
	glEnable( GL_TEXTURE_2D ); //enable texturing
	gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
	square();
	glutSwapBuffers();
	angle ++;
}
void reshape (int w, int h) {
	glViewport (0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode (GL_PROJECTION);
	glLoadIdentity ();
	gluPerspective (60, (GLfloat)w / (GLfloat)h, 1.0, 100.0);
	glMatrixMode (GL_MODELVIEW);
}

int main (int argc, char **argv) {
    glutInit (&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA);
	glutInitWindowSize (500, 500);
	glutInitWindowPosition (100, 100);
    glutCreateWindow ("A basic OpenGL Window");
    glutDisplayFunc (display);
	glutIdleFunc (display);
	glutReshapeFunc (reshape);

	texture = LoadTexture( "texture.raw", 256, 256 ); //load our texture

    glutMainLoop ();

	FreeTexture( texture );

    return 0;
}