// File: navigate.cc

// Summary: Use the joystick to navigate through an environment, where
// the world extends beyond the CAVE coordinate system.
// Joystick Y value controls forward and backward speed.  
// Wand direction controls direction of travel.

#include <unistd.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <cave_ogl.h>

// Make a 3 x 3 'world' of squares, each 100 units on a side.
#define BLOCK_COUNT 3
#define BLOCK_SIZE  100

#define SPEED  4

// Colors for the blocks.
float colors[9][3] = { 1.0, 0.0, 0.0,
		       0.5, 0.0, 0.5,
		       0.0, 0.0, 1.0,
		       //
		       1.0, 0.5, 0.0,
		       0.5, 0.5, 0.5,
		       0.0, 0.5, 0.5,
		       //
		       1.0, 1.0, 0.0,
		       0.5, 1.0, 0.0,
		       0.0, 1.0, 0.0
};

void appProcCompute ();
void renderProcDraw ();

void main (int argc, char ** argv)
{
  CAVEConfigure (&argc, argv, NULL);

  CAVEInit ();

  CAVEDisplay (renderProcDraw, 0);

  while  (!CAVEgetbutton (CAVE_ESCKEY)) 
    appProcCompute ();

  CAVEExit ();
}


void appProcCompute ()
{
  static float oldTime = 0;

  float newTime = CAVEGetTime ();
  float elapsedTime = newTime - oldTime;
  float joystickY = CAVE_JOYSTICK_Y;
  float wandDir[3], deltaPos[3];

  // Find how far to move...
  if (fabs (joystickY) > 0.2) {
    float distance = joystickY * SPEED * elapsedTime;

    // ...and in what direction. 
    // Get the wand's direction vector.
    CAVEGetVector (CAVE_WAND_FRONT, wandDir);
    for (int i=0; i<3; i++)
      deltaPos[i] = wandDir[i] * distance;

    // Add in this translation to the CAVE navigation matrix.
    CAVENavTranslate (deltaPos[0], 0.0, deltaPos[2]);
  }

  oldTime = newTime;
}


void renderProcDraw ()
{
  // Clear the z-buffer and set the screen to blue.
  glClearDepth (1.0);
  glClearColor (0.2, 0.2, 0.8, 1.0);
  glClear (GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

  // Apply the CAVE navigation transform.
  CAVENavTransform ();

  // Draw a multi-colored ground plane.
  // 'glRectf' draws a rectangle in xy-plane.  
  // Rotate rectangle 90 degrees around 'x' to lay flat.
  // Shift the collection of squares in the xy-plane to center 
  // the "world" at the CAVE's center.

  glTranslatef
    (-0.5*BLOCK_COUNT*BLOCK_SIZE, 0.0, -0.5*BLOCK_COUNT*BLOCK_SIZE);

  for (int i=0; i<BLOCK_COUNT; i++) {
    for (int j=0; j<BLOCK_COUNT; j++) {
      glColor3fv (colors[i*BLOCK_COUNT+j]);
      glPushMatrix ();
      glTranslatef (j*BLOCK_SIZE, 0.0, i*BLOCK_SIZE);
      glRotatef	(90, 1.0, 0.0, 0.0);
      glRectf (0, 0, BLOCK_SIZE, BLOCK_SIZE);
      glPopMatrix ();
    }
  }
}