/*
 * Copyright (c) 1996-1999  Silicon Graphics, Inc.  All rights reserved.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF THE
 * POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* mouse.c - use the mouse to control the location of the viewpoint
 *
 *  Escape key 		 	- exit the program 
 *  Left Mouse Button		- change incidence and azimuth angles
 *  Middle Mousebutton		- change the twist angle based on
 *				  horizontal mouse movement
 *  Right Mousebutton		- zoom in and out based on vertical
 *				  mouse movement
 *  R Key			- reset viewpoint
 */

#include <GL/glut.h>	/* includes gl.h, glu.h */

#include <math.h>
#include <stdio.h>	/* for printf */

#include "axes.h"
#include "shapes.h"

/*  Function Prototypes  */

GLvoid  initgfx( GLvoid );
GLvoid  drawScene( GLvoid );
GLvoid  reshape( GLsizei, GLsizei );
GLvoid  keyboard( GLubyte, GLint, GLint );
GLvoid  mouse( GLint, GLint, GLint, GLint );
GLvoid  motion( GLint, GLint );

void resetView( GLvoid );
void polarView( GLfloat, GLfloat, GLfloat, GLfloat);

void printHelp( char * );

/* Global Definitions */

#define KEY_ESC	27	/* ascii value for the escape key */

/* Global Variables */

enum		actions { MOVE_EYE, TWIST_EYE, ZOOM, MOVE_NONE };
static GLint		action;

static GLdouble		xStart = 0.0, yStart = 0.0;

static GLfloat		beamWidth = 2.0f, beamHeight = 0.4f, beamDepth = 1.0f;
static GLfloat 		nearClip, farClip, distance, twistAngle, incAngle, azimAngle;

void
main( int argc, char *argv[] )
{
	GLsizei width, height;

	glutInit( &argc, argv );

	width = glutGet( GLUT_SCREEN_WIDTH ); 
	height = glutGet( GLUT_SCREEN_HEIGHT );
	glutInitWindowPosition( (width / 2) + 4, height / 4 );
	glutInitWindowSize( (width / 2) - 4, height / 2 );
	glutInitDisplayMode( GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE );
	glutCreateWindow( argv[0] );

	initgfx();

	glutMouseFunc( mouse );
	glutMotionFunc( motion );
	glutKeyboardFunc( keyboard );
	glutReshapeFunc( reshape );
	glutDisplayFunc( drawScene ); 

	printHelp( argv[0] );

	glutMainLoop();
}

void
printHelp( char *progname )
{
	fprintf(stdout, "\n%s - use the mouse to control the viewpoint\n\n"
		"Axes: X - red, Y - green, Z - blue\n\n"
		"Left Mousebutton	- move eye position\n"
		"Middle Mousebutton	- change twist angle\n"
		"Right Mousebutton	- move up / down to zoom in / out\n"
		"<R> Key		- reset viewpoint\n"
		"Escape Key		- exit the program\n",
		progname);
}

GLvoid
initgfx( GLvoid )
{
	GLfloat maxObjectSize;

	glClearColor( 0.0, 0.0, 0.0, 1.0 );
	glShadeModel( GL_FLAT );
	glEnable( GL_DEPTH_TEST );

	/* Maximum size of all the objects in your scene */
	maxObjectSize = sqrt( ((2*beamWidth) * (2*beamWidth)) +
				((2*beamHeight) * (2*beamHeight)) +
				(beamDepth * beamDepth) );

	/* Set up nearClip and farClip so that                        */ 
	/*    ( farClip - nearClip ) > maxObjectSize,                 */
	/*    and determine the viewing distance (adjust for zooming) */
	nearClip = 1.0;
	farClip = nearClip + 8*maxObjectSize; 

	resetView();
}

GLvoid
reshape( GLsizei width, GLsizei height )
{
	GLdouble			aspect;

	glViewport( 0, 0, width, height );

	aspect = (GLdouble) width / (GLdouble) height;

	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	gluPerspective( 45.0, aspect, nearClip, farClip );
	glMatrixMode( GL_MODELVIEW );
}

GLvoid 
keyboard( GLubyte key, GLint x, GLint y )
{
	switch (key) {
	case 'R':
		resetView();
		glutPostRedisplay();
		break;
	case KEY_ESC:	/* Exit whenever the Escape key is pressed */
		exit(0);
	}
}

GLvoid 
mouse( GLint button, GLint state, GLint x, GLint y )
{
	static GLint buttons_down = 0;

	if (state == GLUT_DOWN) {	/* most recent button down wins */
		buttons_down++;
		switch (button) {
		case GLUT_LEFT_BUTTON:
			/* in case there are only two mouse 
			 * buttons, shift-left is equivalent to the
			 * middle mouse button
			 */
			if (glutGetModifiers() == GLUT_ACTIVE_SHIFT)
				action = TWIST_EYE;
			else
				action = MOVE_EYE;
			break;
		case GLUT_MIDDLE_BUTTON:
			action = TWIST_EYE;
			break;
		case GLUT_RIGHT_BUTTON:
			action = ZOOM;
			break;
		}

		/* Update the saved mouse position */
		xStart = x;
		yStart = y;
	} else {
		if (--buttons_down == 0)
			action = MOVE_NONE;	/* no more buttons down */
	}
}

GLvoid
motion( GLint x, GLint y )
{
	switch (action) {
	case MOVE_EYE:
		/* Adjust the eye position based on the mouse position */
		azimAngle += (GLdouble) (x - xStart);
		incAngle -= (GLdouble) (y - yStart);
		break;
	case TWIST_EYE:
		/* Adjust the eye twist based on the mouse position */
		twistAngle = fmod(twistAngle+(x - xStart), 360.0);
		break;
	case ZOOM:
		/* Adjust the eye distance based on the mouse position */
		distance -= (GLdouble) (y - yStart)/10.0;
		break;
	default:
		printf("unknown action %d\n", action);
	}
	
	/* Update the stored mouse position for later use */
	xStart = x;
	yStart = y;

	glutPostRedisplay();
}

void
resetView( GLvoid )
{
	distance = nearClip + (farClip - nearClip) / 2.0;
	twistAngle = 0.0;	/* rotation of viewing volume (camera) */
	incAngle = 0.0;
	azimAngle = 0.0;
}

void
polarView( GLfloat distance, GLfloat azimuth, GLfloat incidence,
			GLfloat twist)
{
	glTranslatef( 0.0f, 0.0f, -distance);
	glRotatef( -twist, 0.0f, 0.0f, 1.0f);
	glRotatef( -incidence, 1.0f, 0.0f, 0.0f);
	glRotatef( -azimuth, 0.0f, 0.0f, 1.0f);
}

GLvoid
drawScene( GLvoid )
{
	static GLfloat		upperArmColor[] = { 1.0f, 0.0f, 0.0f };
	static GLfloat	lowerArmColor[] = { 0.8f, 0.5f, 0.5f };
	
	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

	glPushMatrix();
		polarView( distance, azimAngle, incAngle, twistAngle );
		XYZaxes();

		/* Draw the shoulder centered at the new origin */
		glTranslatef( 1.0f, 0.0f, 0.0f ); 
    		glColor3fv( upperArmColor );
		WireBox( beamWidth, beamHeight, beamDepth );

		/* Draw the lower arm at the end of the upper arm and 
	 	 * rotate it 45 degrees */
		glTranslatef( 1.0f, 0.0f, 0.0f );
		glRotatef( 45.0f, 0.0f, 0.0f, 1.0f );
		glTranslatef( 1.0f, 0.0f, 0.0f );
    		glColor3fv( lowerArmColor );
		WireBox( beamWidth, beamHeight, beamDepth );
	glPopMatrix();

	glutSwapBuffers();
}