About Hive

//
// Hive
// 3d, texturing, midi sound, threads, music
// 
// Auld May 2006
//
#include <process.h>
#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <math.h>
typedef unsigned int uint;
typedef unsigned char uchar;
static uint i,thump;
static GLUquadricObj *q;
static HMIDIOUT device; 
static uint col = 0x101080FF;

// Counts the number of bits in an unsigned integer
// Note clever trick ot terminate early by testing the integer
// to see if it is already 0, after shifting it
const static uint bitCount (uint n)
{
int count=0;
     do{
         // is there a 1-bit at least sig bit of n 
         count += n & 1 ;  
         // shift n
         n >>= 1 ;
     }  while (n);      
     return count ;
} 

static uint note;
// runs in a seperate thread
// addTune creates the music and makes midi clss to play it
static void addTune (void *p)
{
   do {
       // must sleep or this thread will just absorb all CPU!!
        Sleep(160);
        // set a useful instrument on midi channel 40...
        midiOutShortMsg(device, 0x27c1);//19 or 22 or 27
        // MAGIC! Keep incrementing note. Then count number of bits
        // This gives fractal like music with selfrepetiion! Amazing.
        note+=31;
        // thump is used here and also for synching in size of cylinders...
        thump =  bitCount(note); 
        // thump is used for the midi tone value.
        // It is shifted by 8 to get to right place in midi instruction 
        // and shifted by 3 to multiply tone up a bit
        midiOutShortMsg(device, (thump <<10)|0x00400091);
   }while(1);
   // we dont need to exit as when we exit the main process this thread is also killed.
}

// Here we capture a texture from the screen...thats all
// Unless we call glTexParameteri(, the texture is not diplayed properly
static void texture () 
{
   glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
   glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 0, 0, 256, 256, 0); 
}

// Draws a cube of objects about the origin
// 2*loop +1 objects are drawn (-loop to loop) in each dimension
static void drawGrid (const int loop) 
{
int z,y;
   int x=-loop;    
   do {
     y=-loop;
     do {
     z=-loop;
        do {
             glPushMatrix();
             // the colour is a cheat, we cast an int to pretend its an array of 4 bytes
             glColor4ubv((uchar*)&col);
             glTranslatef(x,y,z);
             // SYNCH!!!!! Thump is used here from the music routine to synch the cylinder length
             gluCylinder(q, 1, 1, 0.05f*thump, 8, 8);
             glPopMatrix();
             z++;
        } while (z-loop);
        y++;
     } while (y-loop);
     x++;
   } while (x-loop);
}

void WINAPI WinMainCRTStartup()
{   
  uint g;           
  PIXELFORMATDESCRIPTOR pfd;  
  pfd.cColorBits = pfd.cDepthBits = 32; 
  pfd.dwFlags    = PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;	
  PVOID hDC = GetDC ( CreateWindow("edit", 0, 
                      WS_POPUP|WS_VISIBLE|WS_MAXIMIZE, 
                      0, 0, 0 , 0, 0, 0, 0, 0) );         
  SetPixelFormat ( hDC, ChoosePixelFormat ( hDC, &pfd) , &pfd );
  wglMakeCurrent ( hDC, wglCreateContext(hDC) );
  ShowCursor(FALSE);  
  q = gluNewQuadric();
  gluQuadricTexture (q,GLU_TRUE);
  midiOutOpen(&device, MIDI_MAPPER, 0, 0, 0);
  // launch the music rendering as a seperate thread
  // Then we must set the thread priority to be highest possible so that
  // the music is rendered at a consistent rate...
  SetThreadPriority(_beginthread( &addTune,0,0), THREAD_PRIORITY_TIME_CRITICAL);    
  do {
    // if we dont handle state here, our second cube of cylinders will be fucked up in some
    // intersting but not useful way...
    glEnable(GL_TEXTURE_2D);
    if (i> 200) glDisable(GL_BLEND);
    glEnable (GL_DEPTH_TEST);
    // This cube of cylinders, the solid ones close to us
    // is from -3 to 3
    g =3;
    // capture whats on the screen...
    texture();
    // Tricky to explain but we only clear the screen and swap buffers 
    // on every other loop. This enables us to call drawGrid just once
    // despite drawing two cubes of cylinders...
    if (!(i&1)) {
      SwapBuffers ( hDC );
      glClear ( GL_DEPTH_BUFFER_BIT| GL_COLOR_BUFFER_BIT ); 
      glDisable (GL_TEXTURE_2D);
      glEnable(GL_BLEND);
      glDisable(GL_DEPTH_TEST); 
      // The first cube of cylinders drawn will go from -6 to 6
      g=8;
    }
    // crucial, nothing is drawn without this
    glLoadIdentity(); 
    // viewing angle 120, aspect ratio 1, near, very near and far at 128 units
    gluPerspective(120, 1, 0.01f, 128.0f);
    glBlendFunc(GL_SRC_ALPHA,GL_ONE);
    // These two make us move through the cube of cylinders
    glTranslatef (0,1,1);
    if (i>300) glRotatef (i-300,1,1,1);
    drawGrid(g);

    // my sucky global counter   
    i++;
    if (GetAsyncKeyState(VK_ESCAPE) ) ExitProcess(0);
  } while (1);
}